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NGS MicroShell - Harte Technologies

1. Example B 0 F Auxiliary file search on B 0 F Auxiliary file search off B 0 G Line feeds removed from input B 0 G B O 1 B O new disk logged into CP M for writing ol p nsD Su gives CR LF B O p SnDrive D User U gives CR LF Drive A User 0O B O S displays status report B O U B O echo this is upper case THIS IS UPPER CASE B O U B 0 echo this is lower case this is lower case B O V All commands echoed comfile test data pip b a test pip b a data B O V No echo of commands T Section 2 4 09 APPENDIX G INDEX Character 6 character 36 ST input 38 App F Character 7 20 Character 7 22 character 3 Character 7 C 7 7 App F App F App F us 37 App F App F App F App F App F 37 App F 24 App F haracter haracter gt Character 7 Character 7 Character 7 Character 7 PAA vVv A oe Appending to a File 19 Argument Substitution 36 Auto Load MicroShell 51 Automatic File Search 12 31 Auto File Search Extensions 32 47 Automatic Program Search 29 C Programming Language A 1 E 1 i ar Changing Disk Drives 4 Changing MicroShell Responsible File Extensions 47 hanging Initial Flag Defaults 51 hanging the Initial Prompt 15 hanging the Search Path 47 hanging the Shell File Extension 47 Command Files 35 Command Line Length 7 Command Li
2. Johnson Stephen C UNIX Time Sharing System Language Development Tools Bell System Technical Journal 57 1978 1971 90 Kernighan Brian W and Plauger P J Software Tools Reading Massachusetts Addison Wesley 1976 Kernighan Brian W and Ritchie Dennis M The C Programming Language Englewood Cliffs Prentice Hall 1978 Thomas Rebecca and Yates Jean User Guide to the UNIX System Berkeley California OSBORNE McGraw Hill 1982 Char gt ST St SP Sp Appendix F Summary of MicroShell Commands Special MicroShell Characters in Command Line Meaning Output Redirection OF console Output Redirection OF Printer Input Redirection Pipe output to input of next cmd in shell and input files causes next character to be its control equivalent character on a shell causes line to b a comment ignored When first file line treated as Echo redirected Output to Console Return character ready to console input status calls Separate commands Treat arguments with embedded spaces or tabs as 1 argument and ignore special characters inside quotes Ignore special meaning of next character Argument substitution in shell command files 0 18 WordStar like Command Line Editing Redirect in a shell Input back to console file Redirect Output to Printer Example stat gt filename pip lst file gt prntfile ed file lt script p
3. the file being erased matches one in MicroShell s list it will look down the search path for the file This can have some undesirable effects if the user is not aware of what is happening like the wrong file gets erased Be careful in selecting the MicroShell responsible extensions A command file which turns off the file search feature xecutes the desired program and then turns the file search back on is one way to solve this problem Two specific programs are used frequently enough to warrant MicroShell automatically handling this situation PIP and COPY COPY was chosen as the frequent name given to many copy programs MicroShell will automatically turn off the file search flag when either of these programs are run and then turn it back on if it was initially on after the programs terminate without any user action If for some reason the user really wants the file search feature to be active with these features the programs can be renamed so that MicroShell will not recognize them MicroShell does NOT recognize a pip or b pip i e it does not check for a prepended drive name there s only so much room for checking in an 8K program so get in the habit of NOT typing pip and copy with drive prefixes The MicroShell search features represent a powerful tool which the user can selectively configure for his needs With the above limitations in mind the user can customize MicroShell to most ffectively
4. For example if the shell file disasm sub contained the following lines ddt 1 com gt 1 asm L100 2 GO and was executed by typing disasm test 1000 then the first line would cause MicroShell to load DDT with the file test com loaded by DDT and output redirected to TEST ASM When DDT called for the first line of console input MicroShell would supply the line 37 Shell Files L 100 1000 DDT would then output a listing of test com from 100 hex to 1000 hex which MicroShell would redirect to the file TEST ASM When DDT called for a second line of input MicroShell would supply the line Go causing DDT to exit MicroShell would then close the file TEST ASM and return to the user with the prompt for the next MicroShell command This example demonstrates th power of MicroShell to make a more powerful tool by combining existing tools The user could edit the resulting file as desired and reassemble it A disassembler for free 4 6 1 Changing the Default Input Redirection Input redirection to a shell file may be changed from the default input redirection from the shell file itself which has the same effect as XSUB in a submit file by issuing an explicit input redirection command in the shell file In the above example if the first line of the shell file disasm sub were changed to ddt 1 com gt l asm lt script then MicroShell would supply command lines to DDT from the fi
5. 3 The C compiler used to develop part of MicroShell BDS C uses two com files to compile a program After completing the first pass the first comt file ccl com chains to the second com file cc2 com to generate the compiled code Although a command flag for ccl is available to specify the drive from which cc2 is to be loaded MicroShell can relieve the user of this detail 3 6 Some Practical Limitations There are some limitations which the user should keep in mind in using MicroShell s file search features 3 6 1 MicroShell permits up to six disk drives to be automatically searched The disk drive search path path can be set by the user Section 4 9 4 As delivered MicroShell has only Drive A in its search path The user should remember that each drive which MicroShell checks requires a finite amount of time the drive must be selected and the directory read by CP M This time will depend on the user s particular computer system and disk drives and how many drives are checked Therefore the user should make the search path as short as possible while satisfying his particular needs 3 6 2 To accomplish the automatic file search MicroShell must compare the file extension on every failed attempt to open a file with the list of file extensions for which MicroShell is responsible Eight extensions are permitted to be MicroShell responsible file extensions In the as delivered progr
6. Now you can build your own prompt You can put the prompt command in a shell file and execute it when desired by typing the name of the shell file Look at our examples normprmp sub and fullprmp sub on the distribution disk Or you can permanently change the default prompt see Section 5 1 Maximum Prompt Length 40 characters Note that with an intelligent terminal some really unusual displays can be generated For example you could always have the prompt clear the screen or change pages One word of warning don t end your custom prompt string in a single The prompt processing routine does not handle every possible error A single ending would mean that the next character was special and since there is no next character a real problem can occur Also remember to include the prompt string in double quotes if it has any spaces tabs or special characters in it It s easiest just to use double quotes all the time wo 2 4 8 S Flag Status Report The S Flag provides a display of the status of various Microshell features including the Flags The S Flag can be issued as S or S or S or s The report looks like this F File Search On G Gobble Line Feeds On M Mode End of File CP M UNIX CP M T Transparency Character Flag oft U Upper Case Command Translation On V Verbose Echo shell files On P String Prompt String n D u D 1 NNN Input Char
7. need not have the preceeding 43 Shell Files Example sendless loop optional statements Sgoto endless loop lt expression gt lt var gt lt op gt lt var gt lt var gt lt op gt lt constant gt lt op gt equal not equal NE not equal less than less than or equal greater than greater than or equal al Example ol ol AS stop then goto doexit LE if SA LT D then return C SA ole lt action gt goto lt label gt I return lt assignment gt I exit Example loop optional statements A 1 if SA 6 then exit A D 4 9 3 2 Input Statements The following input statements may be used to input values to variables Statement Action getchr lt var gt Get one character into variable from input Don t forget to use lt T if the input is to come from the console instead of the shell file You would almost always want the input to come from the console Example Fl Sprint n Enter selection sgetchr AS lt ST 44 sgetstr lt var gt Example Shell Files Get a string of characters into variable from input terminated by a carriage return Again use ST for input from console Sprint n Enter file name sgetstr FS lt ST Smemnum lt var gt Example Cntfile smemnum A Sprint A Smemstr lt var gt Example
8. see Section 4 9 4 If the Transparency Flag is turned ON all of the above special character meanings are ignored i e every character is sent to the program without any interference by MicroShell MicroShell will only take end of file action at the physical end of the last sector of the input file which may be up to 127 characters after the end of the text in the file i e after th control Ze So the program must handle end of file recognition if you want to stop reading when a control Z is read Note that this mechanism allows passing object code files through a filter if you want With the Transparency Flag on MicroShell s action at the physical end of file the end of the last sector in the file still depends on the state of the M Mode of End of File Flag In the CP M mode input will revert to the keyboard in the UNIX mode a control Z will by sent followed by a carriage return See Section 2 4 6 above Note that the state of the Gobble Line Feed Flag has no effect if Transparency is ON Microshell automatically handles turning ON the Transparency Flag when a pipe is invoked by the user unless overridden S Section 2 7 1 CAUTION If you turn the Transparency Flag ON in a line of a shell file it must be turned off later in the same line or MicroShell may not be able to read the lines from the shell file properly As an example th following shell file will work properly sample filter shell fil
9. Programs can ask CP M for input 12 Automatic Program Search characters from the keyboard in two ways they can ask for one character at a time BDOS call 1 or 6 or a line of characters until a carriage return is typed BDOS call 10 Now consider our file which we want to use as input If the program calls for a line of input characters Microshell will supply successive lines from the file automatically stripping the carriage return and line feed from the end of each line Since the program called for a line of input MicroShell knows that it shouldn t send the carriage return and linefeed This is the most common call for input characters DDT takes its input from this type of call as does the command mode of the CP M editor ED So everything works fine On the other hand if the program calls for its input one character at a time the linefeed after each carriage return in a file is probably going to confuse most programs since the program is probably expecting the user to type a line of input followed only by a carriage return Leaving the linefeed out of the script file is one solution but when the file is type d all the lines appear on top of each other distinctly confusing the user Having MicroShell always throw away Jlinefeeds after carriage returns is an alternative solution This works fine for most programs like CP M s ED in the insert mode and most editors But what if you wanted to write a program tha
10. 52 MicroShell Customization 2 SHSAVE must be executed from MicroShell since it copies the current status of MicroShell s variables to the new SH COM file If not executed from MicroShell SHSAVE responds with bell sounds MicroShell must be loaded to use SHSAVE 3 If SHSAVE can t find SH COM one any of the disks in MicroShell s search path it responds with bell sounds Can t find SH COM 4 SHSAVE checks the SH COM it finds to see if it is the right version If it s not you probably have a pre 2 0 version of SH COM on one of the drives in the search path SHSAVE responds with bell sounds SH COM is either wrong version or bad copy 5 If SHSAVE can t write the new SH COM to disk it responds with bell sounds Disk full or write protected Make room for the new SH COM or specifY a different disk drive That s all there is to it MicroShell sh com now becomes your customized Note Be sure not to run shsave on your master diskette of it first make a copy The autocpm program will permit you to semi automatically patch your CP M system to have it load MicroShell on initial startup and run an initial command It is semi automatic because autocpm requires that SYSGEN first be run to put the CP M system in memory This manual step is necessary because CP M is normally stored on the first two tracks of your diskette and the method of putting it there and getting it from there to ch
11. All of these keywords begin with S and must be the first non white space character on the logical command line so that MicroShell will recognize them 4 9 3 1 Control Statements The following control statements are recognized Statement Sexit Sgoto lt label gt if lt expression gt then lt action gt Action Unconditional exit to command level Unconditional transfer of control to line with lt label gt Conditional transfer of control based on value of expression siffile lt filename gt lt present absent gt then lt action gt sreturn lt assignment gt where Conditional transfer of control based on presence or absence of file filename If driv specifier given on filename then only that drive is searched for the file filename If no drive specifier given then MicroShell will perform auto search if filename s type is in the list of MicroShell responsible file types Unconditional return to previous shell file if nested or command level Optional assignment of a value toa variable is allowed e g sreturn SC 1 Note Since SA and B are local to each shell file assigning a return value to them would not be logical lt label gt string beginning with that is not an extended shell keyword The label must be the first non white space on a physical not logical line of a shell label reference in the GOTO or THEN clause fil
12. C lt RETURN gt The second character of the Command Line and some additional non destructive default on lete character to the left of cursor from cursor to the end left of cursor left of cursor Action Cursor forward a character Cursor back a character Cursor forward a word Cursor back a word Cursor to end of line Cursor to beginning of line Toggle insert flag Delete character under cursor De Delet ntire lin D te lin D te line to the Delete word to the Delete word to the right of cursor Undo all editing and restore original line Abort editing and return to MicroShell prompt Execut dited lin 27 Editing commands can be upper Automatic Program Search or lower case or the corresponding control code i e delete to end of can be entered as QY Qy or Q Y line The bell will sound if an attempt is made to make a command line greater than 79 characters due to the single physical line capability of the command line editor The definition of a word in the Command Line Editor is a little different from WordStar s rules to conveniently stop the cursor at frequently changed spots Word separators are space gt lt and i These are customizable by the user S Section 5 2 Tabs and other control characters are not handled by the Command Line Editor you can use them fr
13. Sets the character recognized to cause the input to a program running from a shell file to revert to the console if encountered in the input stream would normally be used to allow the user to enter text from the console and then shell file later with Default None Hex is not allowed Changes the string in specified to upper case Sprint n Quit getchr AS lt ST Supcase AS Sif SAS Y then exi 49 revert back to the Sschar Null 0 the string variable Esgus Y N 54 0 MicroShell Customization MicroShell Customization MicroShell as delivered on the distribution disk is set up for the average user but since many different environments are possible under CP M many users will want to customize MicroShell for their particular needs Level Two levels of customizing MicroShell are provided Level 1 and Level 2 1 customization is very easy and almost automatic It allows the prompt flags search path shell file type shell file scratch drive screen clear addit string and the special shell file characters to be changed In ion Level 1 customization allows semi automatic patching of CP M to permit loading MicroShell automatically each time you start up your computer IF YO comma UR CP M IS CLOSE TO STANDARD Level 2 allows changing the number of directory columns for the dir nd page length for the typ comma
14. This Flag has an argument the new prompt string For xample th proper command to get the default prompt back is p n D u Note the ending space Well here are the syntax rules for the prompt string The syntax is a rough takeoff from the formatted print syntax for the C programming language Character Meaning Special character next character means something special N or n New line carriage return line feed Sn means substitute a carriage return and linefeed Note that unless you want a really unusual display most prompt strings should begin with n D Upper case drive letter SD substitutes the currently selected drive in the prompt string D Lower I case drive letter d as above U or u User number u substitutes the currently selected user number into prompt string 15 Automatic Program Search Since S has special meaning to get a S to print in the prompt string enter two s If embedded spaces or tabs are desired in the prompt enclose the whole prompt string in quotes like we did for the default prompt If a bell or some other control character is desired in the prompt just type the actual control character into the prompt string Alternatively if you do not enclose the prompt string in quotes you may use the up arrow letter combination e g G for the bell Note that if you do not enclose the prompt string in quotes embedded spaces or tabs are not permitted
15. execute as follows 1 Microshell looks first on the current drive in the current user area for a com file with the same root name e g in the above example Stat com If this file is found it is loaded and executed 2 If the file is not found in step 1 Microshell looks at the current user number If the user number is greater than 0 Microshell looks on the current disk drive in the user 0 area for the com file If found the file is loaded the user number restored from 0 to the initial user number and the program is executed If the com file is not found in user O or user 0 was the initial user area MicroShell s search proceeds to step 3 3 Microshell now looks at the search path specified by the path xtended shell function Section 4 9 4 The Spath search string can specify up to 6 additional disk drives for Microshell to check As delivered disk drive A is specified in the search path but the user may change the search path to fit the needs of his system Microshell continues the search for the com file in user area 0 of the disk located on one of the specified disk drives If the file is found Microshell loads it restores the user number and default disk drive to their initial values and executes the program If the com file is not found after searching all drives in the search path Microshell proceeds to the next search step 4 Since there is not a com file with the ro
16. from progl is sent to the input of prog2 and the output of prog2 is sent to the input of prog3 The vertical bar is the command for MicroShell to create a pipeline Pipes are actually a shorthand for output redirection of the first program followed by input redirection of the second program The UNIX user will excuse this simplification of the full UNIX inter process communication capability MicroShell permits the same output and input modifiers and to be used with pipelines to achieve simultaneous console echo and or console status redirection For example the command progl prog2 would echo the output of progl to the console as it was being fed to prog2 The command progl prog2 would cause MicroShell to send character ready status to prog2 for its input These two modifiers may be combined in the same pipe as progl prog2 The order of the and is not significant The MicroShell pipe function is implemented using temporary files which MicroShell erases after the pipe is complete The MicroShell pipe function is better understood by knowing that internally MicroShell actually performs a pipe as follows progl gt pypel prog2 lt pypel gt pype2 prog3 lt pype2 The names for the temporary pipe files pype were chosen to avoid conflict with a user s existing file names Our apologies to anyone who had been using pypel pype2 etc MicroShell will e
17. meet his needs by handling repetitive mundane details of finding programs Customizing MicroShell is covered in Section 5 34 Shell Files 4 0 Shell Files MicroShell s shell file capability provides all of the functions of CP M s submit feature and adds some additional features This capability allows the user to have MicroShell execute a series of commands from a file This file is often called either a shell file or a command file Sections 4 1 4 8 cover the basic shell fil features Section 4 9 covers extended shell file features 4 1 Constructing the Shell File Using an editor the user types the desired command lines into a file pip filename con may be used to more quickly create a short file Remember to explicitly type the line feed after a carriage return which the editor normally adds automatically The filename for the shell file should have an extension of sub to allow MicroShell to recognize it as a shell file This extension may be changed by the user Sshext S Section 4 9 4 Any of MicroShell s features may be included in the commands placed in the shell file with the following restrictions T Flag If the Transparency Flag is turned on in a shell file line it must be turned back off in the same line S Section 2 4 9 X Flag This is the last command MicroShell will execute before exiting to CP M Another shell file If another shell file is c
18. of the command line by MicroShell before it is passed to the main command White Space in Command Lines In general white space spaces or tabs may be used freely in commands to MicroShell In particular white space is optional before and after redirection symbols lt gt pipe symbols and semicolons One place there cannot be white space is between a redirection symbol or pipe symbol and a or modifier For example stat gt out stat gt tout and stat gt out are all legal command lines but stat gt out is not The other MicroShell special commands are covered in detail in the following sections and summarized in Appendix F 2 3 1 Escaping MicroShell Special Characters The characters gt lt Mpt mem MA min and double quotes have a special meaning to Microshell when used anywhere in a command line Two of these special characters can be permanently changed if desired by the user 7 the multiple command separator and the command line editing character See Section 5 2 for a discussion of how to change these characters If it is desired that one of the other special characters be used ina command line for non MicroShell functions i e the user program needs them their special meaning may be ignored by MicroShell in one of the following three ways 1 Precede the special character with an i e save 1 gt
19. operation under CP M If the user keeps a disk with all routinely used programs in disk drive A he can then operate from drive B in any user area without concerning himself with where his programs are located The user merely types the desired command line and MicroShell does the work of finding the program For single drive systems the user can move to any user number on drive A without copying his programs to that user number Users with a hard disk may wish to customize MicroShell to reflect their system configuration Section 5 If the hard disk is drive C for xample the user may wish to change the as delivered search path from drive A to drive C Or the user could specify that drive C be checked first after the default drive check which cannot be omitted and then drive A The flexibility is available to satisfy the user s needs 333 File Search As a separate search function MicroShell performs a search for any files which a main command Le a program may attempt to open If for xample the user issued the command ddt file ext from drive B under CP M without MicroShell CP M would load ddt com from drive B and execute it DDT would then attempt to load the file file ext from drive B If DDT didn t find file ext on drive B it would issue the error message and await another command MicroShell oversees all attempts of a program to open files If the
20. printer dBase II reports WordStar printer output etc MicroShell will redirect all output which a program is sending to the printer to a file instead with the command B O program gt prtfile where program is any program which produces output to the printer and 20 Automatic Program Search prtfile can be any filename into which to redirect the output The sign if added causes the output to be echoed to the Printer in addition to going to the file e g B O program gt prtfile Redirection of console output and printer output cannot be done simultaneously 2 5 5 Cautions in Redirecting Output 1 If output containing control characters is redirected some care must be exercised with control Z s 1A Hex Since a control Z is used by CP M and many CP M programs to mark the end of a text file the first occurrence of a control Z is usually considered to be the end of the file To most of the editors and word processors around the rest of the file just isn t there So if output containing control Z s is redirected to a file a simple utility can be written as a filter to remove the control Z s from the file Note that the filter will have to be used with the Transparency Flag on and the Mode Flag set to CP M to allow the user to enter a unique character like at the end to exit the filter Then th nd of the file may have to be cleaned up with an editor 2 When redirecting a pr
21. the end of a long explanation what we do is turn off the Verbose Flag set the Mode to UNIX and turn on the Transparent Flag We don t have to worry about the Gobble Line Feeds Flag because if the Transparent Flag is on there are no special characters So pipes will automatically work right for filters which is their most common use If you want to use pipes in some other way you can override this automatic setup see Section 5 2 2 8 Command Line Editing How many times have you typed in a long command only to see a mistake you made near the beginning of the line and have to erase it and start over Or how often have you given a command only to have the program or CP M complain about some little error Microshell has a built in Command Line Editor which allows you to edit the current command line you re typing or go back and edit the previous line Command line editing is invoked by pressing either during command entry or at the command prompt If the is the first character on the line the previous command line will be echoed for editing If the is not the first character i e you re in the process of typing in a command and you see an error the current command line is echoed for editing The enter Command Line Editing character may be changed if it conflicts with normal commands you type Note that you can never include this character in a command line you type We could have provided an es
22. the user e g domac test MicroShell would issue the commands MAC TEST LOAD TEST ERA TEST HEX The space containing the 2 in domac sub would be closed up by MicroShell 4 4 Control Characters ina Shell File If control characters are necessary in a shell file they may be entered with an editor that will insert actual control codes or they may be entered by the sequence uparrow letter C where C is the letter associated with the control code i e TAB I When MicroShell reads the line it will substitute the appropriate control character for the C sequence If a is really desired in the file it must be escaped with a i e This substitution occurs when lines of a shell file are read and during input redirection 4 5 Comments in Shell Files If a command line in a shell file begins with or the entire line is ignored by MicroShell in executing the shell file This permits commenting of shell files for future edification understanding etc Command lines may be commented out therefore by merely placing a or at the beginning of the line 4 6 Input Redirection in Shell Files In addition to permitting normal input redirection lt in a shell file command line MicroShell provides a default redirection of input to the shell file if no other redirection of input is specified This is analogous to the action of CP M s XSUB placed in a submit file
23. which shsave doesn t handle DDT must be used to patch MicroShell and the patched MicroShell must then be save d The locations for these patches are given in Appendix D 59 APPENDIX A History and Design of MicroShell We began using CP M in January 1978 It was a vast improvement in microcomputer operating systems relatively easy to use efficient in memory and disk usage and a tremendous bargain for its price We happily used CP M and its facilities to develop software adapting to its various features and limitations Then in 1980 a revolutionary event occurred we were introduced to the UNIxtm operating system developed by Bell Laboratories for the Digital Equipment Corporation PDP 11 minicomputer series W wer lated Always having been shy about big computer operating systems and their complexity UNIX pleasantly surprised us It was easy to learn easy to use and very powerful The user interface to UNIX is its shell program equivalent to CP M s Console Command Processor CCP The idea for MicroShell really began when we used a DEC VAX minicomputer Instead of being greeted at the terminal with DEC s operating system VMS we saw what looked like UNIX s Shell The Software Tools which began in a book by the same name by Kernighan and PI auger and wer later xpanded by Lawrenc Berkeley Laboratory at the University of California had been installed on top of DEC s operating system The Software Tools incl
24. 31 Automatic Program Search attempt by the program to open a particular file is unsuccessful MicroShell steps in to help out the program as follows 1 MicroShell has a list of file extensions or file types for which it is responsible Sftype See Section 4 9 4 The file extension is ext in the example above in general th fil xtension is the part of a filename after the If MicroShell sees that a program was unsuccessful in opening a file and the file extension of the file name is one for which MicroShell is responsible and if the program didn t specify a disk drive when opening the file then an automatic file search is performed Now what s this specify a disk drive mean In CP M when a program tries to open a file there are two ways of telling CP M where to get the file from The program can tell CP M exactly what drive to find the file on In this case MicroShell assumes that the program knows what it s doing and doesn t interfere Most of the time however the program tells CP M just to open the file on the default drive and lets CP M figure out what drive that is In this case MicroShell will step in if the open attempt fails and begin automatic searching For the technical types this is the drive code in the File Control Block Only if it is 0 meaning the default drive does MicroShell do automatic searching Then when MicroShell finds the file it changes the drive code to the proper drive It tu
25. CP M This exit will occur in one of five ways xecutes a return instruction that 1 Program are designed not to overlay the exit CP M prompts Under MicroShell the MicroShell any output redirection files command If the command line multiple commands used program If MicroShell is execu i the next command in the shell fil for the next if then MicroShell loads and This is what programs do Without MicroShell when they command without doing a warm start prompt occurs after MicroShell closes the program was executed as a single ncluded more commands to execute xecutes th next Section 4 0 then CP M CCP ting a shell file e is executed 2 Program jumps to location 0 which is the warm start entry point for CP M Without MicroShell CP M normally does a warm start before prompting for the next command Under MicroShell action is the same as in 1 above nQ warm start occurs 38 CP M executes a warm start as in 2 above the same as in 1 above Program calls CP M System Reset BDOS call 0 Without MicroShell Under MicroShell action is 22 Automatic Program Search 4 User enters a control C as the first character in a read console buffer BDOS function 10 call Without MicroShell CP M executes a warm start as in 2 above Under MicroShell action is the same as in 1 above If input redirection is in effect or a shell file is being executed with input from the s
26. Can t open the input tile Requires SH OVR Error 4 gt Missing command name Requires SH OVR Error 5 gt Redirection file name missing Requires SH OVR Error 6 gt Read error on SHTMP in shfile Can t Shell Line Shell Line MicroShell Error Messages Cont find label Name of Label file syntax error NNNNN gt line with error is printed A goto on line NNNNN referenced a label which could not be found Labels must be the first word on a physical line of the shell file An xtended shell keyword e g print goto return clear exit etc cannot be a label Upper lower case is significant on labels file syntax error NNNNN gt line with error is printed A syntax error in an extended shell file function occurred in a shell file being run The error is on line NNNNN of the shell file See Section 4 9 Typical errors are improper number of arguments in a statement e g an if statement without a then clause mixing variable types assignment of a numeric variable to a string variable variable letter out of range variables go from A to G remember the old ABC jingle ABCDEFG etc String too long Shell Line file syntax error NNNNN gt line with error is printed A string assignment in a shell fil xceeded the 128 total bytes of shell string storage See Section 4 9 Sclear can be used to clear all shell string variables APPENDIX C MicroShell Compatibility wi
27. Command 4 Search Path 31 47 Search Automatic Command 31 App F Input 21 Input Status 22 Search Automatic File 31 Semi colon 7 App F Shel File Extension She Files 35 Shel Flags 10 App F Software Tools A 1 E Changing 48 1 Special Characters App F Character 7 character 36 T input 37 Ap Character 7 Character 7 Character 37 Character 7 lt Character 7 gt Character 7 gt gt Character 7 App F pE 20 App F 22 App F App F App F App F App F INDEX Cont Sta SUB tus Report 16 File Extension 48 Sub Sum Sumi Sys TYP U F UNI UNI Upp USE V F War X F Z mit Files with MicroShell 39 mary 1 mary of Commands App F tem Requirements 1 E CP M Command 4 lag 18 X A 1 E 1 X Reference Material APP er Case Commands 18 R CP M Command 4 lag 18 m Starts CP M 22 39 lag 18 Control 14 ea
28. MICROS HELL UNIX Features for CP M User s Manual Version 2 0 December 9 1982 Copyright c 1982 New Generation Systems Inc 2153 Golf Course Drive Reston Va 22091 703 476 9143 All Rights Reserved COPYRIGHT NOTICE Copyright c 1982 by New Generations Systems Inc All Rights Reserved No part of this publication may be reproduced for Commercial purposes without the express written permission of New Generation Systems Inc TRADEMARKS The following trademarks are referenced throughout this manual ACT 80 ACT 86 PASCAL M SuperCalc DS C ompuPro P M CBASIC MAC MP M ince pellbinder nica NIX WordStar SpellStar GanzaQaaw Sorcim Corporation BD Software Leor Zolman Godbout Digital Mark of Lexisoft Knowlogy Bell Tel Electronics Research Corporation the Unicorn jo LENS MicroPro phone Laboratories International Corporation Introduction How to Run MicroShell without Reading the Manual Everyone is always anxious to run a new program without having to read through the manual first Here s how to run MicroShell l Copy the distribution disk before you do anything else It should have the following programs on it SH COM MicroShel SH OVR MicroShell Overlay File See paragraph 7 below SHSAVE COM Microshell Customization Program See Section 5 0 AUTOCPM COM CP M Patcher for AutoLoad of MicroShell See Se
29. YPE filename Type a file TYP paged variation SAVE nn filenam Save nn 256 byte pages of memory beginning at 100 Hex drivename Change default drive user NN Change user area to NN Allows access to areas 0 31 CP M only allows access to 0 15 while 16 31 can only be accessed from a user program call to CP M where afn is ambiguous file name e g Automatic Program Search We will assume that the Microshell user is familiar with these CP M commands The new CP M user may wish to review these commands in the Digital Research CP M documentation The CP M CCP also provides the user with certain line editing functions to change a command line which has been entered in error prior to executing it e g backspace delete control u x r e etc These line editing features are supported by MicroShell Again the new CP M user may wish to review these commands in the Digital Research documentation Microshell also provides an enhanced WordStar like command editing capability which can be used to edit the current or previous command line This facility is described in detail in Section 2 8 Microshell provides a variant of the CP M TYPE command TYP TYP may be used to type a file with automatic pauses after each pageful The default setup displays 23 lines of the file and then waits for the user to type any character before proceeding to display the next page The user may use control C durin
30. acter Delay 0 D 2 NNN Input Line Delay 0 D 3 NNN Output Prompt Delay 0 D 4 NNNNN Input Ignore Factor 0 path str Disk Drive Search Path A sftype str File Types Auto Search SUB OV COM sshext str File Type Shell Files SUB ssdrive char Scratch Drive Shell Files A sclrstr str Screen Clear String Z Ibreak on off Break during Shell Files On sbochar char Break Character Esc sexchar char Program Exit Character None Stchar char Revert to Keyboard Char None eschar char Revert to Shell File Char None 16 Automatic Program Search The first 11 lines in the display are the Microshell Flags and the remaining lines which begin with ar xtended shell commands See Section 4 9 for an explanation of th xtended shell commands The status display is one of the features which requires the SH OVR overlay file If Microshell can t find the overlay file it will sound the bell and display the error B O s Requires SH OVR B O 2 4 9 T Flag Transparency Character Flag On Off Default Off During input redirection and pipes a special case of input redirection certain characters in the input file have special meaning Take next character literally ignore special meaning a Make next character a control character CR Remove following LF if Gobble Flag is on Control Z End of input file Sexchar Program exit character if set see Section 4 9 4 Stchar Revert Input to terminal character if set
31. alled within a shell file known as nesting shell files MicroShell needs to save the current shell file parameters in a temporary file Th xtended shell function Ssdrive Section 4 9 4 determines what disk drive MicroShell writes this scratch file to It is set to drive A in the distribution version but it may be changed by the user The disk in that drive must not be changed during execution of the shell file or nesting will fail Note the disk must also not be marked as Read only by CP M You can do a disk login L at the beginning of a shell file to ensure this THIS TEMPORARY FILE IS USED ONLY IF NESTING OCCURS With these restrictions all other MicroShell commands including redirection pipes multiple commands on a line shell Flags and CP M commands ERA DIR REN TYPE USER default drive selection may be included MicroShell will perform normal disk drive searches for programs specified in shell files as described in Section 3 35 Shell Files 4 2 Executing Shell Files and Argument Substitution To execute a shell file under MicroShell the user types the name of the shell file with or without the extension followed by any arguments to be substituted in the commands in the shell file For example if the file show sub contained the following line type 1 stat 1 and was executed by typing show doc MicroShell will substitute d
32. am these are set to sub ov and com but the user may change these Sections 4 9 4 and 5 1 As with the search path the user should specify only those file extensions which are necessary for his situations 3 6 3 There will be times when the user may not want MicroShell to do any automatic file searching MicroShell has a Flag f Section 2 4 3 which permits the file search feature to be turned off and on from within MicroShell Thus the user can turn it off while he runs one particular program and then turn it back on Or he may create a shell file Section 4 to take care of the details of this Flag and to execute a particular command The Status Flag s may be used to determine if file search is turned off or on 33 Automatic Program Search 3 6 4 Some programs scan the disk directory with a special CP M system call search search next for a desired file prior to attempting to open it If they don t see the desired program in the directory they don t try to open the file MicroShell can t help these programs because it is not possible to easily determine what file the program may be searching for e g it may be using a wild character or in the search 3 6 5 Some programs look for a file to erase before or after performing some action Copy utilities like CP M s PIP are an example of these The user must remember that if file search is enabled and the file extension of
33. ange vary from system to system So we made it as easy as possible Here are the steps 1 Copy sysgen com to one of the disks in your computer 2 Execute sysgen to get CP M into memory B 0 sysgen SYSGEN signs on and prompts Source drive name or RETURN skip a answer a Source on A then type return lt press RETURN Function complete lt got system Destination drive name or RETURN to terminate lt press RETURN B 0 53 MicroShell Customization 3 Run autocpm with your desired initial command line See Section 2 1 for the initial commands you can give MicroShell For example if you want to run MicroShell when you start up your computer and have MicroShell shift to drive B you would type B O autocpm a sh b AUTOCPM Automatic Initial Command for CP M lt AUTOCPM signs on Copyright 1982 New Generation Systems Inc CP M patched Run SYSGEN now lt and reports completion Press RETURN for Source Drive For DESTINATION drive enter drive you want new CP M system written on B O AUTOCPM Error Messages You may get one of the following error messages from AUTOCPM 1 If you forget to give an initial command line after typing autocpm bell sounds Usage autocpm lt command line to be installed gt or autocpm null to set no auto start command Notice the syntax for entering NO initial command i e taking an initial command you ve put in ba
34. calc 12 77 22 88 Smemstr A Sprint A 1 SAS newprog 1 Get numeric value from memory at 80H and place in variable named This provides a mechanism for a program to pass a number for subsequent processing by the shell file Note that the number must be gotten with Smemnum before the next executable program is run since the command line for programs is stored at 80h The number should be a two byte binary value with the low byte at 80h and the high byte at 81h cntfile is a user supplied program possibly in basic which counts the number of files and stores its result at 80h Get a null terminated string of characters from memory at 82H and place in variable named This provides a mechanism for a program to pass a string for subsequent processing by the shell file Note that the string must be gotten with Smemstr before the next executable program is run since the command line for programs is stored at 80h calc is a user supplied program possibly in basic which stores its result as a null terminated string starting at 82h 45 Shell Files 4 9 3 3 Output Statements The following output statements may be used to output information from a shell file Statement Sprint n lt var gt I lt constant gt Example Sprint SAS Action Output the value of a variable or constant to the output stream followed by a carriage return and a line feed The n opti
35. cape character for it but there s only so much room in 8K you know However you can use the Command Line Editor to put in a See Section 5 2 for instructions on how to change the enter Command Line Editing character or any of the editing commands themselves Please note that this feature in no way affects CP M s normal command line editing features you can still use backspace rubout del control H U and X if you want MicroShell s Command Line Editing works like this After you type no carriage return is required the appropriate command line is echoed and Microshell waits for the editing command It looks like this B O last command line lt cr gt last command runs B O lt you decide to edit the last command Edit Mode Insert On lt Edit Mode signs on with Insert Status last command line lt Microshell displays A cursor is here 26 Or if you re typing the current command and you see an B O this comand line Edit Mode error Insert On lt A here you type Edit Mode signs Automatic Program Search error I to edit line on with Insert Status this comand line lt MicroShell displays A cursor is here Standard WordStar cursor movement and editing commands are accepted commands Command 4D S or backspace AF A AQD Ags AV G DEL or RUBOUT Ny QY Q lt DEL gt AQT AT U lt ESC gt or
36. ck out again 2 If AUTOCPM cannot find the proper patch points in memory bell sounds AUTOCPM requires that CP M image must be placed in memory by SYSGEN before using If this has been done and this message still appears then your version of CP M is not a standard CP M 2 2 and AUTOCPM cannot be used to patch in a command If this message occurs either SYSGEN did not properly read your CP M system into memory or your CP M system is not standard S the comment on non standard CP M systems at the end of this section 4 Run SYSGEN immediately after running AUTOCPM without doing any other operations in between This is important since the new CP M system is in memory awaiting the SYSGEN B O sysgen SYSGEN signs on and prompts Source drive name or RETURN to skip lt press RETURN Destination drive name or RETURN to terminate a lt enter A Function complete lt wrote system B O The new CP M system is now written back out on drive A Test that it properly runs the initial command you specified to AUTOCPM by pressing your reset button and rebooting the system 54 MicroShell Customization Non Standard CP M Svstems If the new disk does not run the initial command you entered your system manufacturer has probably modified the standard CP M system and you will have to get his assistance in making this change Or find a good CP M systems programmer There have been several arti
37. cles in Microsystems magazine concerning patching CP M to run an initial command If you have the source code for your BIOS and are familiar with assembly language programming you should be able to figure out your particular system Note that with this initial command installed in CP M any time you do a cold or warm boot of your system your initial command will be executed So if you exit MicroShell with the x Flag the initial command will be executed again This will reload MicroShell if the command you installed does that In other words you can t escape to CP M There are two tricky ways to do it though If you leave the disk drive prefix off sh when you specify the initial command to AUTOCPM then MicroShell will only be loaded on the initial cold start of the system and whenever you exit MicroShell from Drive A If you exit MicroShell from drive B CP M won t be able to find sh if it s not on drive B and you ll stay in CP M Then it won t reload MicroShell until you do a warm start AC from drive A The other way to defeat the initial command is to erase or rename the program sh com that the ini tial command tries to execute Do this ina shell file called for example escape sub ren a mysh com sh com x Now you just say escape and you end up in CP M DZ Level 2 Customization of MicroShell evel 2 customization allows changing a number of additional MicroShell fea tures
38. ction 5 0 D COM Expanded Directory Program Public Domain Author Unknown MENU SUB Sample Menu Shell File ERASE SUB Sample Shell File FULLPRMP SUB Demonstration shell files which will change the prompt NORMPRMP SUB Qs With CP M running in your computer type sh followed by a carriage return of course 3 Microshell will sign on with a B O prompt or A O depending on what disk drive you re on 4 Give Microshell a few CP M commands like dir and stat to assure your self that it s working ore Now try one of MicroShell s features type dir gt files You shouldn t see anything but the disk will click as Microshell puts the directory listing into the file files Look at files by typing type files There s your directory Now let s try another Microshell feature multiple commands Type dir gt gt files type files Now you see a second directory appended the gt gt to the end of the first And the second half of the command line executed as soon as the first was done Intro 1 Introduction 6 Now try this Type fullprmp Now you ve got a new prompt that includes the disk drive the user number and a bell to tell you when a command is done If you got a fullprmp you haven t copied the sub files on the distribution disk to the disk you re using Go back and do that and then continue If you don t like that prompt type normprmp and you get the B O pr
39. ds MicroShell History and Design App A MicroShell Error Messages App B MicroShell Compatibility App C Customization Locations App D UNIX Reference Material App E Summary of Commands App F Index App G The new user of MicroShell should first read the Preface How to Run MicroShell without Reading the Manual following the examples by actually using MicroShell After he has gained an initial familiarity with MicroShell basic MicroShell Commands Section 2 0 will provide more details on using MicroShel1 Automatic Program Search Zed Basic Microshell Commands This section will cover the basic Microshell Commands including 2 1 Executing Microshell 2 2 CP M like functions 2 3 Forming MlcroShell command lines 2 4 MicroShell Flags 2 5 Output Redirection 2 6 Input Redirection 2 7 Pipes 2 8 Command Line Editing 2i Executing Microshell The Microshell program is named sh com and is executed by typing sh or sh initial command line from the CP M prompt A gt if the user is logged into CP M on the A disk drive Microshell will respond with MicroShell Version X X Copyright c 1982 New Generation Systems If an initial command line was given the command is executed prior to the initial A O prompt A O The default MicroShell prompt displays the drive letter in upper case followed by the current user n
40. e An input redirection in the first half or an output redirection or another pipe in the second half of the pipe are legal Missing command name There was no command name where MicroShell expected one E g after a semi colon in a command line after a pipe symbol etc Redirection tile name missing There was no file nam iven after a gt or lt redirection symbol g y Read error on SHTMP MicroShell couldn t read the file SHTMP which is the scratch file used when a shell file is nested The disk specified as the shell file scratch drive sdrive Section 4 9 4 must not be changed when shell file nesting is used Requires SH OVR A function was called which requires the MicroShell overlay file SH OVR and the file could not be found The overlay file is required for the append function If the MicroShell status report s all xtended shell functions beginning with e g Sif Sprint etc and command line editing Either the TOET file type must be in the automatic search file type list Stype or SH OVR must be on the disk drive you are logged in on Some error messages are shortened to a number as shown below when the MicroShell overlay file is not present Requires SH OVR Error 0 gt More than one output file Requires SH OVR Error 1 gt More than one input file Requires SH OVR Error 2 gt Output tile and pipe Requires SH OVR Error 3 gt
41. e is complete Now we knew that this would not solve everyone s problem so we made provision for the user to override this automatic action See Section Die Die We said the Gobble Line Feed Flag was effectively turned off Actually there are two other potential problems that are tied to the CR LF problem When the program asks for input you normally expect to see that input echoed on the screen as you type it Should the echo of the input go into the output file Of course you say How about the case of a filter which is translating its input to upper case You surely don t want the input characters in the output Well then of course we don t want the input in the output Well how about the case where you re feeding commands into an program and you re trying to collect as output an example of the program actually in action Well you probably wouldn t use a pipe but you might So to echo or not to echo Now the other problem special characters MicroShell does a number 25 Automatic Program Search of things based on reading special characters See Section 2 3 1 above If you are using a filter you don t want Microshell messing with any of the characters in the file There s a Flag for this the Transparency Flag When the Transparency Flag is on Microshell just reads the input file literally and passes the characters to the program taking no action on any special characters Finally getting to
42. e feeds during B O G Default Input redirection Line feeds removed from input g or G Don t gobble line feeds during B O G Input Redirection Si op Login current disk after B O 1 or changing disks B 0 new disk logged into 1 or CP M for writing p or P Prompt string p Sn D u gives or Uses C like format p or P Next char special CR LF B O gives n N Newline CR LF SnDrive D User U gives d Lower case driv D Upper case driv CR LF Drive A User 0 u U User number s OL SS Shell Status report B O S Shows status of flags displays status report tu or U Upper case translation of B 0 U default command line like CP M B O echo this is upper case THIS IS UPPER CASE u or U No case translation on command B O U line allows passing lower case B O echo this is lower case command line to a program this is lower case v or V Verbose mod B O V All commands echoed comfile test data Echo command before execution pip b a test pip b a data v or VI Disable Verbose mod B 0 V No echo of commands x or X Exit MicroShell and return to B O x CP M B gt Additional Flags D Section 2 4 2 M Section 2 4 6 T Section 2 4 9 Intro 4 Table of Contents Overview IT System Requirements T2 Summary of MicroShell Kea rG Basic MicroShell Commands 2 1 Executing MicroShell 252 CP M like Functions 223 Forming MicroShell Gonna nines 3 1 Escaping M
43. e with explicit input redirection t filter lt filel gt file2 t nextcmd 17 Automatic Program Search In a pipe Microshell takes care of the Transparency Flag sample filter shell file with pipes type filel filter gt file2 nextcmd 2 4 10 U Flag Upper Case Command Line On Off Default On The U Flag permits the command line passed to a program to either be in the CP M compatible upper case only mode or in upper lower case as the user types it This is the command line which is set up at 80 Hex by the CP M CCP or Microshell prior to executing a program Regardless of the state of this Flag Microshell translates all file names i e the main command name and the setup o_ the secondary file control blocks at 5C and 6C Hex to upper case to remain compatible with CP M upper case file names It is often desirable to pass a program upper and or lower case arguments Issuing the U Flag will permit this Note on the other hand that some programs will not like to s lower case arguments so use this capability with caution 2 4 11 V Flag Verbose Mode Command Echo On Off Default On The V Flag permits the user to have Microshell echo all input redirection and shell file input to the output If output redirection is also in effect then the input characters are also redirected to the output file In addition each line read from a shell file is echoed to the screen just prior to execu
44. editing to be included without impacting on the resident memory requirements of MicroShell The BDS C package is still used for management of the 90 individual modules linking and overlay management This package BDS C represents an excellent assembly language development environment MicroShell is executed from CP M by typing sh CP M loads in MicroShell which then relocates itself below CP M just below the Basic Disk Operating System BDOS MicroShell replaces th CP M Console Command Processor CCP and performs all of the functions of the CP M CCP plus additional UNIXshell like functions It remains resident during execution of programs until it is deliberately exited by the user In this respect it is Similar to Wordstar and other programs which themselves perform CCP functions while remaining resident Appendix B MicroShell Error Messages Filename MicroShell cannot find the file Filename to execute along its search path See Section 3 for an explanation of MicroShell s search path CP M Error Messages The CP M Basic Disk Operating System BDOS issues various other messages beginning with BDOS ERROR ON Drive See the Digital Research CP M documentation for the meaning of these errors Error Can t open the input tile Occurs during input redirection MicroShell can t find the file specified on the command line as the input redirection file E
45. eely in your command lines and they won t bother MicroShell but you will have some difficulty in using the Command Line Editor on those lines As an aside if you are a softwar developer we think command line editing is an important user friendly feature of a program editing the input easily especially if complex or long lines of input are required W will happily discuss selling the source code for this feature Just give us a call 28 Automatic Program Search 3 0 Automatic Program Search Microshell contains two automatic search features to simplify operation under CP M main command i e the com or shell file search and file search 3 1 Main Command Search If the user enters the command stat to CP M CP M first looks for the program stat com loads the program from the disk into main memory and then executes the program The program to be executed will be called the main command CP M will only look in one place for the program on the current disk drive under the current user number If the user is logged onto disk drive B in user number 0 CP M will look on disk drive B for a file stat com in user area O If CP M does not find stat com on the current drive in the current user number CP M will display the error message stat and prompt the user for another command Microshell expands CP M s normal search for a file to
46. epending on who wrote the program it may be expecting lines terminated by CR LF or it may be expecting only a CR There s no standard in this area because UNIX like filters are new to the CP M environment Reading a line at a time from the input and then performing some action on the whole line This may also be a filter but more commonly it is a program getting commands rather than characters to process an editor for example In this case it is probably expecting a line of characters followed by a CR just the way you would type it from the keyboard So we have a problem about what to do with the LF which follows the CR in our input file of data or commands Strip out all the LF s or not UNIX by the way does not have this problem since the end of line character is specified as the newline a linefeed Previous versions of MicroShell left the user to decide what to do and set the Gobble Line Feed Flag accordingly That was a problem and a nuisance The Solution to the Problem What MicroShell does now is this whenever a pipe is invoked by the user MicroShell assumes that a filter is being used Not too many people actually pipe commands to editors etc We further assume that the program expects to see every character in the file including CR s and LF s So the Gobble Line Feed Flag is effectively turned off automatically for the duration of a pipe and then restored to its previous setting after the pip
47. esult in a BDOS error Issuing the L Flag either L or L or 1 or 1 there s no difference will cause MicroShell to login drive A login the disk on the drive the user is currently on the default drive and reset all other disks in the system 13 Automatic Program Search Then if the user selects a new drive CP M will log it in as read write For example if the user is currently on drive B and wants to put a new disk in drive B he performs the following steps 1 Change the disk in drive B 2 Type L or L followed by a carriage return The head will load on drive A to login A and then on B to login B Since B was the default drive Both drives A and B are now logged back into CP M for read and write If another drive is selected after th L CP M will log it in again since it forgets all disks logged in prior to the L command All of this happens without the warm start that usually happens in CP M This is good and bad Good because it s quicker Good because on some double density systems it permits a single density disk without CP M on the system tracks to be logged into drive A permitting for example PIPing between two single density disks Why bad Bad because in some double density systems density selection only occurs during a real warm start On these systems MicroShell must be exited to log in a different density disk Try your system to see what it requires The CompuPro system we use
48. f the file Limitations on Multiple Commands Th feature o ar several restrictions on the use of the multiple command MicroShell h K 1 The maximum command line length of 84 characters cannot be exceeded The total command i e all characters entered up to the carriage return is counted not just each individual semicolon separated command 2 Only 17 arguments are permitted for each semicolon separated command That is a main command and 17 arguments to the main command 3 Any commands on a lin after th MicroShell exit Flag x are ignored since MicroShell relinquishes control to CP M after the x Flag is executed 4 4 Any redirection specified in one command is not carried over to the next semicolon separated command For example stat gt statout dir will cause only the stat output to be redirected to the file statout while the directory display from dir will come to the console as it normally would This is not really a restriction it is what would logically be expected to happen It is mentioned to clarify the scope of action of redirection 5 Some programs use the semicolon as a special character themselves Provision is made to change the character MicroShell uses for multiple command separation See Section 5 2 2 3 3 Interrupting a MicroShell Command If a series of commands are given on one line previous versions of MicroShell prov
49. file will create a filename gt file _To get a to be passed through to MicroShell type two s i e Automatic Program Search save 1 will create a file named 2 Enclos th ntir argument containing the special characters in double quotes i e save 1 gt lt will create a file named gt lt Note that quotes cannot themselves be enclosed in quotes but must be escaped with a 3 During input redirection special character meaning may be escaped by setting the Transparency T Flag on Using this Flag has some other effects which should be studied in Section 2 4 9 The characters and have a special meaning after gt lt or and has special meaning after gt These characters must be escaped with a if the user really wants to have the or as part of the file or command name It is best to stay away from the special characters they re not common in file names anyway The dollar sign character followed by a number from 0 to 18 has special meaning in a shell file argument substitution This special meaning can be escaped by using double dollar signs to be compatible with CP M Three other characters may be assigned special meaning in input files sexchar Stchar and S schar See Section 4 9 4 for the meaning of these characters and how to assign them To round out the discussion of special MicroShell characters all or t
50. g the pause to abort the rest of the display The 23 lines page setting is customizable by the user for other than the standard 24 line terminals See Section 5 2 Microshell also provides a variant of the CP M _IR command to display system files B 0 dir s will display all files including those marked by STAT as system files Or B O dir s com will display all COM files including system files Wild card characters and may be specified in any of the CP M like commands In standard CP M only era and dir will allow these characters MicroShell permits their use anywhere a file name is specified MicroShell s response to a wild card character is to use the first file name encountered in the disk directory which matches the file specification Thus for example if you type B O type ab Microshell would type the first file name it found that started with ab e g abzzt or abstract etc Notice that this feature does not cause an expansion of the action to multiple files Al though this feature can save some unnecessary typing some care must be used with it As an example if you type B O Microshell will execute the first com file it finds in the directory or even more exciting than that if you type B O save 2 Microshell will first erase all files in the directory before saving 2 256 byte pages into a file named 2 7 2 Th
51. h xtended shell functions will be described in the following sections Section Topic 4 9 1 Shell Variables 4 92 Variable Assignment 429 3 Shell File Programming 4 9 3 1 Control Statements 4 9 3 2 Input Statements 4 9 3 3 Output Statements 4 9 4 Miscellaneous Statements 4 9 1 Shell Variables There are 33 shell variables available for use as follows Variable Variable Comments Name Type SA SG Numeric May hold values 0 65535 no sign positive only A and B are local to each shell file C G are global to any shell files Once assigned a value that value is kept until changed or until MicroShell is reloaded SAS G String May hold variable length strings up to a total string space of 128 bytes A string of N chars requires N 1 bytes All string variables are global and retain their assigned strings until a clear command or MicroShell is reloaded 0 18 String These variables are the 19 argument substitution variables They may be assigned values can then be passed to a program in a command line They hold their value Only until an executable program is run Then all argument substitution variables not specified in the command line are cleared The total space allotted to these variables is 84 chars the max length of a command line 41 Shell Files Note The argument substitution variables are referred to as 0 18 in shell files when assigning values to them or using them
52. he shell Flags Section 2 4 when used by themselves on a command line are recognized by MicroShell as special commands and cannot be escaped 2 3 2 Multiple Commands on a Line MicroShell will accept multiple commands on one line with each command separated by a For example the MicroShell command era bak dir stat is equivalent to giving the following command sequence to CP M A gt era bak A gt dir CP M displays directory A stat stat displays space remaining Automatic Program Search A gt The only difference is that the MicroShell user can give all three commands at once and watch them sequentially execute He doesn t have to wait for each command to complete befor ntering another command The benefit of this feature which comes from the UNIX operating system is that we as human beings think in terms of logical processes which may involve numerous commands to accomplish If we can type in all of the necessary commands to carry out a logical process we are then freed from that level of detail and can concentrate on the results or on the next process Thus the computer and its software has done what it does best keep track of multiple and or repetitive tasks while the user is free to think about logical processes In Section 4 we will cover one higher step in this same philosophy putting a number of individual commands into a file a shell file and executing them by merely typing the name o
53. hell file this control C may be placed in the file as an up arrow C C or as an actual control C if your editor can put control characters ina file 5 As a final method of causing a program to exit a special character exchar can be defined as an exit character in an input or shell file See Section 4 9 4 for a discussion of exchar use Input redirection does not alter the exit that a program makes but the user must remember that the input file must have the same characters in it that would be typed if there were no input redirection I e if a program interprets a blank line Return only to mean exit then the input file must end in a blank line If the program expects a control C or control Z then the input file must have that control character in Lt These control characters make for awkward editing especially control Z and if there s any other way to exit the program it s a lot better to use it and stay away from control characters This may seem difficult to grasp at first but experience will make it clear After the program has processed all the information in an input file what happens next depends on the state of the Mode Flag If the Mode Flag is set for CP M mode input will revert to the keyboard after all characters have been used from the input file Normal operation of the program from the keyboard then continues This is an excellent way to give a program some initial commands and then enter a
54. here is any way to make MicroShell just a little bit smaller With the distribution version of MicroShell the answer is no overlays are already in use for all of the functions which we feel can be allowed to require a disk access and there is no run time facility for decreasing MicroShell s size Neither is it likely that future versions of Microshell will be substantially smaller than 8K MicroShell is now completely written in assembly language with all the tricks we know of to minimize memory size It is possible for us to create a custom version of MicroShell for an individual user with a special need e have done this in the past for a few customers Our charge depends on the effort required but is priced on a time basis Contact us if you have such a need We would emphasize however that creating huge applications programs may cause future problems If there is any possibility that your program will be required to run in a multi user environment in the future many MP M configurations provide only a 48K memory space for user programs Also your operating system may require additional memory when you upgrade to a hard disk or when you upgrade to a new version of CP M So before you exceed 48K we would recommend that you segment your program and use MicroShell s menu features Section 4 9 or use overlays for your program Ji 2 3 Forming MicroShell Command Lines The process of entering a command to MicroShel
55. icroShell Special Characters 3 2 Multiple Commands on a Line 3 3 Interrupting a MicroShell Command NNN MicroShell Flags 4 4 4 4 4 4 4 4 4 4 4 4 NNNNNNNNNN DNDN LY 1 2 3 4 49 6 7 8 9 1 1 1 NFO Output NNN DN LN awww o Oe WN ER Pipes Issuing a Flag Command D Flags Delays F Flag File Search G Flag Gobble Line Feeds Flag Login Disks Se a M Flag Mode at End of File P Flag Prompt Change S Flag Status Report T Flag Transparency Garat Flag U Flag Upper Case Command Line V Flag Verbose Mode Command Echo X Flag eXit MicroShell Redirection Appending Output to a File Echoing Redirection to the Console A Redirecting Console Output to the Printer Redirecting Printer Output to a File Cautions in Redirecting Output Redirection Redirecting Console Status 3 x Normal Termination of Input dedrrleeica Interaction between Pipes and Flags Command Line Editing WDADMDODO ATAU PEPWNNEF O 20 20 20 21 21 22 22 24 25 26 Table of Contents Cont Automatic Program Search WWW WW Ww No WN EH Shel Pe PPB AD NOB WN EF a Main Command Search Benefit of Main Command Search File Search Benefit of aatomatie File Search Some Practical Applications Some Practical Limitations 1 Files Constructing the Shell File Executing Shell Files and Argument Sstt oi Null Arguments Control Characte
56. ided a means of interrupting the sequence of commands This mechanism was somewhat unreliable as it required typing the escape character and having MicroShell see it in between commands Many programs ate up Automatic Program Search any input characters removing the escape character before Microshell could Seen it So this mechanism has been removed from the current version except for during shell file execution see Section 4 7 The only possible way to stop a series of semicolon separated commands now is to freeze the output with control S obviously the program must be doing some output for control S to stop it and then typing control C This normally will abort the entire command line Note that any abort mechanism built into a program such as control C with the BDS C compiler will still abort the program but MicroShell will then execute the next logical command in the line 2 4 Microshell Flags Several of MicroShell s features can be altered by the user from within Microshell itself These commands to Microshell are called Flags The following is a summary of MicroShell s Flags and their default settings All default settings can be modified by the user S Sections 4 9 4 and 5 1 Summary of Microshell Flags Flag Meaning Default D Delays 0 F File Search On Off On G Gobble line feeds On Off On L Login disks M Mode End of File CP M UNIX CP M P Prompt change A O S Status repor
57. in expressions but are still referred to as 0 18 when constructing command lines This is necessary or MicroShell would immediately try to do argument substitution on them as it read the shell file As an example consider the following shell file which might be part of a menu program in an office environment sprint n Enter file name to edit Sgetstr 1 lt T if 1 then exit ws 1 lt ST 4 9 2 Variable Assignment Shell variables may be assigned values as follows lt var gt lt constant gt lt var gt lt var gt Variable types must match lt var gt lt var gt lt op gt lt var constant gt lt op gt lt var I constant gt lt lt op gt can be or for numeric variables but only for string variables Examples SAS SBS Assigns string in B to AS GS test string Assigns test string to G Use double quotes to cause leading or trailing spaces SA SA 1 Adds 1 to current value of A SA SA 1 Subtracts 1 from current value of A SD A B SC Assigns sum of A SB and C to SD CS SAS SBS Assigns to SCS concatenation of AS and BS If SAS Hello and SBS world then CS Hello world after SCS SAS BS 1 AS Assigns string in SAS to 1 argument substitution variable 42 4 9 3 Shell File Programming Shell Files Several extended shell file commands are provided to specify the flow of control in a shell file
58. ion See Section 4 9 4 The contents of Sftype are displayed in the status report s Flag As delivered Sftype contains the type sub so Microshell will search for shell files If Sftype does not contain the shell file type Microshell will look no further than the current drive and user for the shell file Please note THE COM FILE AUTOMATIC SEARCH OF STEPS 1 3 ABOVE ALWAYS OCCURS AND CANNOT BE DISABLED Even if com is not in the Sftype list Microshell will still search all the drives in the search path for the com file 6 If the shell file is found in the search path Microshell restores the default drive and user area and begins execution of the shell file If the shell file is not found Microshell displays the following error message stat or whatever the command name was and prompts the user for another command Example The user is initially logged onto disk drive B in user number 1 and issues the command stat The search path will be assumed to be the as delivered path containing only drive A MicroShell s search for stat com proceeds as follows Drive User B 1 B 0 A 0 The user may override MicroShell s normal search path by specifying an explicit disk drive in the command When an explicit disk drive is given Microshell looks first in the current user number on the disk drive specified and then in user 0 of the drive specified For example if the user i
59. is is a fairly unusual Automatic Program Search hypothetical situation which does not in practice cause any problems but the user should be aware of the feature A final CP M function which is also provided by Microshell is control P which toggles the printer on or off With the exception of the differences discussed above all CP M CCP functions execute identically under Microshell and provide the sam rror messages as the CP M CCP on encountering an error condition Some users have asked why Microshell doesn t give an error message if a program is run which is too large to fit under MicroShell It does The sam error message which the CP M CCP issues BAD LOAD will be displayed by Microshell if an attempt to load a program which is too large to fit under MicroShell is attempted Here s the rub Most programs in addition to the memory space they need for the program itself need some space between them selves and CP M for data and the stack Neither Microshell nor CP M can predict how much space this will be So it is possible for a program to successfully load under MicroShell but then not be able to run properly due to insufficient data space Many programs gracefully check the available space and exit with an error message in this case Some just crash At any rate MicroShell responds like plain CP M would have in the same situation Another similar question we get occasionally is whether t
60. issue the command B 0 dolong compile progname argl arg2 arg3 arg4 MicroShell builds submit file and exits to CP M A gt compile progname argl arg2 arg3 arg4 CP M CCP executes SSS sub file to do compile A gt a sh b CP M CCP reloads sh com as last command B O MicroShell restarts goes to drive B or wherever you want and waits for the next command 39 Shell Files Another example of a useful shell file which returns to CP M is the following file called reboot sub a Sprint a sh b gt boot sub submit boot X Execution of reboot will cause CP M to warm start reload sh com and change to drive B This may be used to login a different density disk on those systems requiring a warm start to change disk density For some systems the L Login Flag Section 2 4 5 will work It depends on how the BIOS was written for a particular system 40 Shell Files 4 9 Extended Shell Functions MicroShell recognizes a number of special commands beginning with a percent sign as xtended shell functions and performs a particular action on them Although th xtended shell commands are most useful in shell files they may also be executed as direct commands To be properly recognized by MicroShell an extended shell function must be the first non white space command on a line In other words for readability you may have spaces or tabs at the beginning of a line T
61. ities in the CP M Users Group did not access CP M via its design entry points Some of these programs may not operate correctly with MicroShell APPENDIX D Customization Locations Several MicroShell features are patchable using the CP M debugger DDT or its equivalent We will not describ th us of DDT See the Digital Research CP M documentation for a discussion of how to use DDT 1 Variables in SH COM which can be patched Use SAVE 38 SH COM after all patches are complete Variable Default Location Comment Multiple Command mm OFEAH Both locations must be changed Separator 1A18H Be sure new char does not interfere with any MicroShell special chars Use TPYPE Pipe File PYPE 11B5H 4 chars followed by 0 Upper Name case SP printer string SP 11BAH 5 chars followed by O Upper case ST terminal string ST 11COH 5 chars followed by O Upper case Columns in DIR 4 251BH Set as desired Lines page for TYP 23 17H 2523H Set to your lines screen 1 Edit Command Character 21H 252EH Set to character to enter edit mode Auto Pipe Flag Set 0 25CBH 0 Transparent On 1 No auto set 2 Variables in SH OVR for WordStar like Command Line Editing which can be patched Use SAVE 38 SH OVR after all patches are complete Word Separators for next word last word etc functions 2028H cpi 20H EZ cpi 2Eh LZ CPT saon jand so on ret
62. k on with A O F command or Microshell is restarted from CP M if the user hasn t changed the default F Flag condition This Flag is useful in cases where a program might be trying to erase or rename a file and the user doesn t want that to happen The automatic file search feature is really provided to permit a program to _ files like Wordstar reading its OVR files or CBASIC loading INT files etc When programs are erasing rewriting or renaming files which have MicroShell responsible file extensions the user should be very careful about using the automatic file search feature B sure you know what s happening before files ar rased or changed forever Two common programs fit exactly this category where automatic file search is not desired CP M s PIP file copy utility and several available programs named COPY So MicroShell explicitly recognizes when the user has invoked these two programs and turns the F Flag off When PIP or Copy is complete Microshell restores the F Flag to its previous condition There are no other programs we ve come across which require this Flag off 2 4 4 G Flag Gobble Line Feeds On Off Default On During input redirection MicroShell may be reading a file of commands into a program for example an editor script When the file of commands is created with most editors a carriage return followed by a line feed is placed at the end of each line Now comes the confusing part
63. l is identical to CP M i e the main command or program name is entered first followed by any arguments the command requires For example stat stat is the main command program to be executed and is an argument to stat telling stat to display a list of all files in the current directory actually the current disk drive and user number MicroShell Automatic Program Search accepts an identical command In addition however MicroShell permits additional arguments to be given to perform special MicroShell functions For example if the user typed stat gt statout MicroShell would send the normal output of the stat command to the file Statout instead of displaying it on the console This is called output redirection and is one of the UNIX features brought to CP M by MicroShell It is discussed in detail in Section 2 5 MicroShell s other features input redirection pipes multiple commands on one line etc are similarly invoked The maximum length of a command line to MicroShell is 84 characters A note is in order here about how Microshell works In the previous example stat gt statout Microshell recognizes the gt statout portion of the command strips it from the command finds and loads the file stat com stat never knows that gt statout was typed It sees the command just as if Stat was typed from CP M The other special MicroShell commands are Similarly stripped out
64. le script instead of from the shell file disasm sub itself After the command wi th explicit input redirection terminates MicroShell will revert back to redirecting input from the shell file on successive command lines unless they also contain explicit input redirection commands The user should note that if DDT exhausts the command lines in script MicroShell will not shift the input back to the shell file Some care must be used in writing files for input redirection to ensure they contain sufficient commands to cause their caller to eventually terminate See Section 2 6 2 on terminating a program from an input file 4 6 2 Redirecting Shell File Input to the Console If the user desires to be able to enter input to a program executed by a shell file from the console keyboard a special input file name T or St is provided Thus in a shell file and only in a shell file if a command line contained ddt 1 lt T DDT calls for input would be supplied from the console keyboard The next line which MicroShell reads from the shell file will undergo the normal input redirection process i e if no explicit input direction is given input is redirected to the shell file itself Some users preferred other names for the ST convention so the console input filename is user patchable see Section 5 2 38 Shell Files 4 7 Interrupting Shell Files Pressing the ESCAPE key will i
65. n interactive mode With WordStar for example the initial commands could set up various WordStar features such as margins justification or hyphen help and then allow the user to begin typing There is even a provision made to take some input from an input file shift the input to the keyboard and then shift back to the input file See Section 4 9 4 The UNIX option of the Mode Flag is designed for use with programs which expect a control Z followed by a carriage return at the end of the input file These are typically filters programs which read a stream of characters performing some action on them and then exit at the end of the input stream UNICA is an example In the UNIX mode when Microshell detects the end of the input file a control Z or no more sectors in the file a control Z followed by a carriage return is passed to the program The program must recognize the control Z carriage return and then terminate by one of the methods discussed above If the program calls for more input after MicroShell has sent the control Z carriage return Microshell will force an exit from the program 23 Automatic Program Search 2 7 Pipes A powerful feature of the UNIX operating system which MicroShell also provides is the ability to pipe the output of one program to the input of another program This permits building a powerful command from a series of simple tools If the user types progl prog2 prog3 the output
66. nd multiple command separator character printer and console redirection strings P and T Command Line Editi the C ng characters to name a few Level 2 customization involves the use of P M debugger DDT or its equivalent It requires a familiarity with DDT and some assembly language experience Level 1 Customization of MicroShell The SHSAVE program distributed with MicroShell will permit the user to change Sh com to reflect any changes he has made to any of the following MicroShell Flags and extended shell features Flags Command to Set Feature Default F File Search On G Gobble Line Feeds On M Mode End of File CP M UNIX CP M T Transparency Character Flag Off U Upper Case Command Translation On V Verbose Echo shell files On P string Prompt String Sn D Su D 1 NNN Input Character Delay 0 D 2 NNN Input Line Delay 0 D 3 NNN Output Prompt Delay 0 D 4 NNNNN Input Ignore Factor 0 Refer to Section 2 4 for details on the function of any of the Flags 3l MicroShell Customization Extended Shell Functions Command to Set Feature Default Spath str Disk Drive Search Path A sftype str File Types Auto Search SUB OV COM sshext str File Type Shell Files SUB Ssdrive char Scratch Drive Shell Files A sclrstr str Screen Clear String Z Sbreak on off Break during Shell Files On sbchar char B
67. nes 6 Command Summary App F Commands App F Comments in Shell Files 37 Compatibility App C Control Characters in Shell Files 37 Control Z 14 COPY PIP programs 12 CP M Functions 4 CP M Warm Starts 22 39 Customizing MicroShell 51 Design of MicroShell App A DIR CP M Command 4 Disassembler 37 Disk Change 13 39 Disk Density Changes 13 39 Editing Command Lines 26 End input file 22 ERA CP M Command 4 Error Messages App B Escaping Special Characters 7 Executing MicroShell 3 Exit MicroShell 18 39 F Flag 12 File Search 12 29 31 Flags 10 App F FULLPRMP Program I G Flag 12 Gobble Line Feeds 12 25 History of MicroShell App A Initial Flag Defaults Changing 51 Initial Prompt Changing the 51 Interrupting MicroShell 9 39 L Flag 13 Line Feeds 12 25 Login Disks 13 39 Lower Case Commands 18 Memory Requirements 1 MicroShell Compatibility App C MicroShell Customization 51 MicroShell Design App A MicroShell History App A MicroShell Responsible File Extensions Changing 47 Multiple Commands on a Line 8 NORMPRMP Program ii Null Arguments in Shell Files 36 Overview 1 P Flag 15 PIP COPY programs 33 Pipes 24 Program Search 29 Prompt 15 Prompt String Characters 15 Pype File 24 RATFOR A 1 Redirection Redirection Redirection Output 19 Redirection Termination 22 Reloading MicroShell 39 REN CP M Command 4 Requirements System 1 S Flag 16 SAVE CP M
68. new user or crisp elegant power for an experienced user T1 System Requirements Microshell requires CP M 2 2 at least 32 K of memory and at least one disk drive Microshell requires 8K of system memory when loaded residing directly below CP M A 64K CP M computer will thus appear to be a 56K system to a program running under MicroShell As most commercial software has been written to run under MP M where only 48K is normally available to user programs this memory requirement does not normally restrict the operation of a program The minimum disk space required by the MicroShell program and its overlay is 20K although once loaded neither MicroShell nor its overlay are necessary for most of MicroShell s functions T2 Summary of MicroShell Features Feature Section e Basic MicroShell Commands 2 e All CP M functions ERA DIR REN TYPE SAVE etc 2 2 e Multiple commands on one line 2 3 e Custom user prompt to aid new or experienced users 2 4 e Redirection of output to a file 25 e Redirection of input from a file 2 6 e Pipes Redirection of the output of one program to Zed the input of the next program e WordStar like Command Line Editing 2 8 e Automatic Program and File Search e Command Files similar to CP M s submit capability e Extended Capabilities allowing fast Menu Programs oa FP B UO e Customization of MicroShell Basic MicroShell Comman
69. nsole status call to CP M before calling for input data MicroShell includes a provision for returning character ready to a program If the user types progname lt inputfil MicroSh sees the as a command to return character ready on program requests for console status This has been made a separate command in MicroSh becaus som programs sample console status as a means of determining if the user is attempting to interrupt or abort the program e g type dir ddt etc In thes cases th user would not want to redirect status with the minus sign An extended shell command Section 4 9 4 status true ina shell file is provided to set character Some programs cannot process input characters as fast as MicroShell can supply them when input redirection is in effect These are typically screen oriented programs which have to redraw the screen or issue cursor control commands after various input characters MicroShell has a feature called Input Ignore Factor which causes MicroShell to send a character during input redirection and then send a number of no character ready status returns before sending the next character This gives the program time to process each character before the next is received S Section 2 4 2 2 6 2 Normal Termination of Input Redirection When redirecting input to a program normal termination will occur when the program completes its action and exits back to
70. nterrupt a shell file which is in progress If the program currently running polls console status to see if an interrupt key has been struck two ESCAPES may be necessary to ensure one of them gets past the program and is seen by MicroShell The character recognized as the interrupt shell file character is user programmable In addition the user any disable this function completely if desired S Section 4 9 4 4 8 Shell Files Which Return to CP M It may be desirable to execute a command from MicroShell which requires all of the available working memory in the computer overlaying MicroShell This can be easily accomplished by creating a shell file which in turn creates a CP M submit file and exits to CP M to execute the submit file The time overhead is not significant compared to the run time of programs which require that much memory Here s how to do it Create a shell file say dolong sub which has the following lines in Pts a Sprint 1 2 3 4 5 gt long sub as many args as req d Sprint a sh b long sub Sprint is an extended shell submit long function See Section 4 9 3 3 x This shell file will build a submit file long sub which submit will process to a sub file on drive A x then exits MicroShell to permit the CP M CCP to execute the SSS sub file To execute the shell file to do for example a compile with a compiler that requires all of memory
71. oc for all occurrences of 1 in the shell file and execute the commands The user can see the command lines after substitution has taken place prior to MicroShell actually executing them by turning on the Verbose V shell Flag MicroShell accepts a total of 18 arguments including the argument containing the shell file name sShow in th xample above MicroShell will in fact substitute the shell file name as typed for any occurrences of 0 in the shell file If the character following a in a shell file is not numeric MicroShell will recognize that it is not an argument substitution If there are two s in a shell file MicroShell will substitute one for the two to remain compatible with the CP M submit convention 4 3 Null Arguments To permit shell files to handle a varying number of arguments no error is generated for a missing argument and MicroShell merely closes up the command line with the Sn for the argument that was not specified For xample th Digital Research Macro Assembler MAC will take an optional argument specifying certain options i e MAC filename PZ The S PZ is optional If the shell file domac sub contained the line mac 1 2 load 1l era 1 hex and was executed by typing domac test PZ then MicroShell would issue to CP M the commands MAC TEST PZ LOAD TEST ERA TEST HEX 36 Shell Files If the second argument was omitted by
72. ogram s output to a file the size of the file often grows faster than one would expect Microshell will issue an error message if the disk fills up while it is redirecting output Disk Full 3 Microshell will redirect console output from all sources i e BDOS calls 2 6 and 10 and direct BIOS calls If a programmer wants to send output to the console and not to the file when output redirection is in effect Appendix D should be consulted 4 Input that the user types into a program whose output is being redirected is sent to the file only if the Verbose Flag is on See Section 2 4 11 26 Input Redirection Input redirection is the process of redirecting a program s input from the console i e keyboard to a file For example the CP M command ed filename would normally require the user to enter various edi ting commands from the keyboard If the user is making identical changes to a number of different files entry of the editing commands from the keyboard is not only repetitious but also error prone Under MicroShell the user can place the proper editing commands in a file say edscript and cause ed to take its input from the file edscript by typing the command ed filename lt edscript 21 Automatic Program Search Any program which requires keyboard input can therefore take its input from a file instead of the keyboard 2 6 1 Redirecting Console Status Since some programs make a co
73. ompt back You can change the prompt to your liking See Section 2 4 on Shell Flags Ta SH OVR is the MicroShell overlay file It is necessary for the following functions Expanded Error Messages S Appendix B Append gt gt Function See Section 2 5 1 MioroShell Status s Report See Section 2 4 8 Extended Shell Functions All functions starting with e g Sprint Sif Siffile etc See Section 4 9 WordStar like Command Line Editing See Section 2 8 If SH OVR is not present MicroShell will perform all other functions normally but will respond with Requires SH OVR if one of the above functions is attempted Ls Now you have the beginning of MicroShell and an idea of the power of the UNIX operating system that it emulates under CP M A summary of the special command line characters and shell flags follows Try each feature to get an idea of what MicroShell can do This summary is identical to Appendix F and can be removed from manual and used for reference Intro 2 Introduction Summary of MicroShell Commands Special MicroShell Characters in Command Line Char Meaning Example gt Output Redirection OF console stat gt filename gt Output Redirection OF Printer pip 1st file gt Prntfile lt Input Redirection ed file lt script Pipe output to input of next cmd Progl prog2 Stat pip l
74. on suppresses the carriage return line feed Numeric variables have leading zeroes replaced by spaces Sprint n Strings need not be enclosed in quotes Sprint n unless leading or trailing spaces Sprint are required Sprint n This is print one line 4 9 4 Miscellaneous Statements provided default value permanently to suit For those which have Statement S args lt var gt Sbchar lt char gt Sbreak on off The following miscellaneous statements are default values the user can change the his needs See section 5 1 Action Returns the number of arguments passed to a shell fil o 7 if the shell file copy sub was executed by typing B O copy filel file2 then if the line S args SA is in the shell file copy sub SA would be set to 2 Sets the character recognized to interrupt shell files if break is enabled Default Escape Enables on default or disables off the ability to interrupt shell files with the assigned break character bchar If interrupt driven type ahead is used on your system break should be set off to prevent sampling the input during shell files 46 Statement Sclear clrstr lt string gt Serase Sexchar lt char gt Ox Sexchar none Sftype lt string gt Slocase lt string var gt path lt string gt Shell Files Action Clears shell string assignments Does not clear argument substituti
75. on string assignment or numeric variables Sets the string sent to the output to clear the screen when a Serase command is executed Max 3 characters Default Z Sends clrstr to output to clear the screen Sets the character recognized to exit froma program in a shell file or input redirection file if encountered in the input stream This would normally be used with programs which have no exit command defined or when it is not desired to go through a number of menus to exit a program Null 0 Hex is not allowed Default None Sets file types max 8 for which MicroShell performs auto search e g Sftype subcomov int Note If less than 3 letter types are used a space must be entered for the balance and the entire string qu ted may be used for wildcarding letters in the type Default SUBOV COM Changes the string in the string variable specified to lower case E g Sprint n Quit Y N Sgetchr AS lt ST Slocase SAS Sif SAS y then exit Sets drive search path to drives in string max 6 drives e g Spath abc to check first drive A then B and finally C Default A 47 Shell Files Statement Sschar lt char gt Ssdrive lt drive letter gt S shext lt string gt Action Sets the character recognized to cause the input to a program to revert from the console back to the shell file if encountered in the input stream Thi
76. ond to program prompts if the program requires inputs from the user 2 5 3 Redirecting Console Output to the Printer To redirect console output to the printer Microshell recognizes a special output redirection filename SP or Sp If the user types B 0 dir gt P MicroShell sends the console output from dir the list of files in the directory to the printer instead of to the console This is somewhat similar to CP M s control P function The control P function acts to send all subsequent console output to the printer and to the console until another control P is entered So if the user typed control P and then dir the dir output would be sent to the printer and the console as well as the prompt following the dir listing Using the gt SP feature instead of control P keeps the prompt from going to the printer and allows the user to control whether the output is also echoed to the screen If a is entered after the gt i e dir gt SP then the output is echoed to the screen Many users didn t like the SP convention we chose and preferred variously lst lst lpr etc So we have allowed you to patch your favorite printer name S Section 5 2 2 5 4 Redirecting Printer Output to a File Various situations arise where it is desirable to be able to redirect the characters going to the printer to a file instead Examples are accounting programs which produce some report only to the
77. ot name specified by the user on the command line Microshell now begins a search for a shell file with the specified root name A shell file is MicroShell s equivalent to the CP M SUBMIT file a text file containing lines of commands to be executed Microshell builds the name of the shell file to search for by appending the command file type to the root name In CP M SUBMIT files have a type of SUB and this is the extension used in MicroShell as delivered It is 29 Automatic Program Search specified by th xtended shell function Sshext which may be changed by the user See Section 4 9 4 In UNIX for example shell files often have th extension sh Assuming the user has not modified the shell file type Microshell builds a shell file name of stat sub for our example above Microshell now begins looking for the shell file back on the current drive and user number If found Microshell assumes th fil contains text commands to be executed by MicroShell Execution of the shell file begins See Section 4 for more information on shell files 5 If the shell file is not found in the current drive and user area MicroShell s action depends on whether th user has specified automatic search for files of the command type ie for sub files in our case The types of files for which Microshell will conduct automatic searches are given by the Sftype extended shell funct
78. patch a NOP here cpi 20H add your word separators here aya cpi jand here etc FZ Insert Mode Toggle 2358H db OFFh OFFH ON 00 Off Command Dispatch Table for Editing Commands 2366H 23CEH db dw db dw db lst char 2nd char 2nd char 0 for 1 char commands routine address etc 0 end of table 3 Structure of MicroShell for Programming Interface 0005 base XX0 6H baset3 BDOS 012AH 3333333333 O O OTO OO tOO TOO tts bne Es t Ay Wo men ete h P base MicroShell Intercept Add 1006H if you look at 6H using DDT hook jump to MicroShell routine which determines what BDOS call is being made and vectors it as appropriate BDOS here is a jump to the real BDOS call it for getting past MicroShell table of original BIOS jumps before coldboot MicroShell overlays BIOS jump table warmboot const conin conout Tast punch reader home seldsk Appendix E BIBLIOGRAPHY The following books and articles represent a few of the sources of information on the UNIX operating system and its Shell Bourne S R An Introduction to the UNIX Shell The Bell System Technical Journal 57 1978 2797 2822 Gautier Richard L Using the UNIX System Reston Publishing Company Inc A Prentice Hall Company 1981 Hall D E Scherrer D K and Sventek J S A Virtual Operating System In Communications of the ACM 23 1980 495 502
79. rase the temporary pipe files after the pipe is successfully completed after the input redirection step If a pipe does not terminate normally due to a full disk or an input redirection error the temporary file will be left on the disk for the user to view rase etc Temporary pipe files are always written to the default disk driv ie the drive from which the command was initiated The user must insure that sufficient space exists on the drive for a temporary file containing all the output that the program being piped will generate If the user wants to use another disk drive for the temporary file explicit output and input redirection is necessary e g progl gt a temp prog2 lt a temp era a temp 24 Automatic Program Search 2 6 1 Interaction between Pipes and the MicroShell Flags If you re not a technical type this section will no doubt bore you and you can just skip it without missing anything really important A nasty CP M convention rears its head when input redirection is used the end of line convention In CP M lines of text or commands in files are terminated with a carriage return linefeed pair OD hex and OA hex For brevity let s refer to these as CR and LF When MicroShell is reading input from a file and passing it to a program the program might be doing one of two things Reading characters one by one and performing some action on them This is the filter we mentioned above D
80. reak Character Esc sexchar char Program Exit Character None stchar char Revert to Keyboard Char None sschar char Revert to Shell File Char None Refer to Section 4 9 4 for details on the function of any of the extended shell functions The user just sets up any of the above features as he wants them to be referring to the section referenced The status command s can be used to S the state of these features In addition to the Flags and the extended shell functions SHSAVE also copies the shell variable area to the new sh com So if you want to preset some of the variables just make the necessary assignments before running SHSAVE When the user is satisfied that he has the setup he wants he merely executes SHSAVE from MicroShell E g B O shsave Wrote new MicroShell SH COM on drive B Renamed old version SHBAK COM B O aF SHSAVE looks for a copy of sh com MicroShell itself on the disk automatically changes all values in sh com to match the values currently set and then writes a new sh com on the disk The old sh com is renamed Shbak com B sur there s nough room left on the disk for the new sh com to be written 10K SHSAVE r Error Messages 1 SHSAVE is executed as either B O shsave or B O shsave drive to write new SH COM on If you give an improper argument SHSAVE responds with bell sounds Usage shsave drive
81. res which requires the SH OVR overlay file If MicroShell can t find the overlay file it will sound the bell and display the error B O dir gt gt alldir Requires SH OVR B O Microshell finds the end of the file to be appended to in one of two ways Microshell reads the last sector of the file from the disk and finds the first control Z in the last sector If found this is used as the end of file and appending begins where the control Z was If no control Z is found in the last sector MicroShell assumes the entire last sector is valid data and begins appending to the beginning of the next sector 19 Automatic Program Search Note that if the file contains multiple control Z s such as when the file has been created by redirecting console output containing control Z s as screen clear characters MicroShell may improperly find the end of file The file will need to be purged of extra control Z s before appending to it 2 5 2 Echoing Redirection to the Console Both output redirection gt and appending gt gt may be echoed to the console by following the output redirection symbol with a plus sign Thus the command stat gt filename would result in MicroShell placing the output from stat in the file filename with a simultaneous echo of the output to the console i e a normal console display This permits the user to see what MicroShell is putting into the file and to resp
82. rns out that this handles almost all of the desired situations and avoids many potential problems 2 MicroShell uses the same search path that it uses for main command searching to look for the file which the user program is trying to open Since MicroShell knows that the program was already unsuccessful in opening the file from the current disk drive and user number it is not rechecked by MicroShell Instead user number 0 of the current drive is checked first if the program was running in a user number greater than O If the file is found in user 0 MicroShell opens it and then returns control to the program which u U an then read from the file just as if the file was in the current drive and ser area WRITING TO FILES USING THIS AUTOMATIC FILE SEARCH IS NOT SUPPORTED NDER MICROSHELL AS IT CAN HAVE DISASTROUS EFFECTS Most writing of programs we ve seen is begun with a create file rather than an open file so MicroShell doesn t interfere 3 If MicroShell does not find the file in user area 0 on the current drive the search path specified for main command search is used to attempt to find the file i e with th as delivered search path of drive A MicroShell would look on drive A user area 0 for the file If found MicroShell would open the file and return control to the user program to use the file Note MicroShell changes the disk drive by
83. rogl prog2 stat pip lst con C or c changed to 03 this is a comment this is a comment too stat gt filename progl prog sysgen lt script progl prog2 progl prog2 era bak stat ed test lt script echo This is one argument dir gt file filename gt file copyfile test if copyfile sub contains pip b a 1 then MicroShell executes pip b a test B O mustake ddt lt T dir gt P Summary of MicroShell Commands Cont Shell Flags Flag Meaning f or F Auxiliary file search enabl Default f or F Auxiliary file search disable g or G Gobble line feeds during Default Input redirection g or G Don t gobble line feeds during Input Redirection nom Login current disk or after changing disks tl or p Or P Prompt string Uses C like format or Next char special 6 gives p or P n N Newline CR LF d Lower case driv D Upper case driv u U User number 5 OF S Shell Status report or Shows status of flags s or S u or U Upper case translation of Default command line like CP M U Or U No case translation on command line allows passing lower case command line to a program tv or V Verbose mod Echo commands before execution v or V Disable Verbose mod Default X or X Exit MicroShell and return to CP M Additional Flags D Section 2 4 2 M Section 2 4 6
84. rror Can t open output tile Occurs during output redirection MicroShell can t open the output redirection file The directory is probably full remove some files from the directory and repeat the command Disk Full The disk has filled up while MicroShell is redirecting output or during the first command in a pipe The command is aborted Make room on the disk for the output redirection file or specify a disk other than the default disk on the command line e g Stat gt t ta statout The disk for the temporary pipe files PYPE1 etc cannot be specified it is always the default disk Use output redirection to a temporary file instead of a pipe if another disk is desired tor the temporary file Error More than one output tile Error More than one input file Error Output file and pipe Two output or input redirection files were specified The following are examples of illegal commands Error Error Error MicroShell Error Messages Cont B O stat gt statout gt statoutl Two output files B 0 ed test lt script lt edscript Two input files B 0 type script I ed test lt script Two input files in 2nd half of command B 0 type script gt outfile I ed test Two output files in 1st half of command Note Pipes are actually an output redirection of the first half of the pipe to a temporary file PYPE followed by an input redirection from that temporary file in the second half of the pip
85. rs in a Shell File Comments in Shell Files Sk Input Redirection in Shell Files 4 6 1 Changing the Default Input Redirection 4 6 2 Redirecting Shell File Input to the Console Interrupting Shell Files Shell Files Which Return to CP M Extended Shell Functions 4 9 1 Shell Variables 4 9 2 Variable Assignment 4 9 3 Shell File Programming 4 9 4 Miscellaneous Statements MicroShell Customization ao NF al evel 1 Customization of MicroShell evel 2 Customization of MicroShell ndices MicroShell History and Design MicroShell Error Messages MicroShell Compatibility Customization Locations UNIX Reference Material Summary of Commands Index ii 29 29 Sil 31 32 33 33 35 35 36 36 37 37 37 38 38 39 39 41 41 42 43 43 J 5l 55 Overview 1 0 Overview Microshell is a CP M program which adds powerful user friendly capabilities to the CP M operating system similar to many of the functions available in the UNIX operating system Compatibility with existing CP M software is retained while adding the UNIX features to the operation of existing CP M software New software applications and tools can be designed and implemented with much less effort using the features available in MicroShell Microshell can be tailored to a user s system and experience level providing additional information and help for a
86. s even filled up causing the problem to bomb SuperCalc and Mince ar xamples of this To solve this problem this Delay Flag allows setting an Input Ignore Factor in MicroShell What this does is to supply a character to the program only once for every X times the program asks if a character is ready X is the Input Ignore Factor So if it s set at 500 which is a good value to start with then only once in 11 Automatic Program Search every 500 times the program asks if a character is ready will Microshell return Character Ready status The effect of this is to make shell files and input redirection work fine with these types of programs Additionally it provides a way in addition to the other Delay Flags to set th ffectiv input rate to the program Make sure that this Flag is set back to 0 when you don t need it or all your shell files and input files will run much more slowly 2 4 3 F Flag File Search On Off Default On The F Flag turns MicroShell s automatic file search feature on default and off The automatic search features ar xplained in Section 3 The F Flag only affects file search not command search If the user does not want Microshell to search for files that match MicroShell responsible extensions SUB OV and COM in the as delivered MicroShell the command A O F will turn automatic file search off It will remain off until the user either turns it bac
87. s would normally be used to allow the user to enter text from the console and then revert back to the shell file Null is not allowed Default None Sets the drive on which MicroShell writes a temporary file when a shell file is nested The temporary file is 2 sectors 256 bytes for each level of nesting Some care must be xercised to ensure that this drive is never read only disk swap write protected disk etc Sets the file type of shell files Default SUB Sshift Shifts all argument substitution variables 30 19 to the left I e 1 gt 0 2 gt 1 etc Useful for sequentially processing arguments passed to a shell file Example ERASE SUB v f args A Sprint n erase print n A print files sloop Sprint Erasing 1 era 1 sshift SA A 1 Sstatus on Sif SA GT 0 then goto loop off Sets character status returned to programs true if on i e indicates that a character is always ready or false if Wore default value Setting character status on is the same as saying B O program lt infile from the command Ii nee If sta tus is set on it may be necessary to set the Input Ignore delay Section 2 4 2 to prevent swamping the program with input 48 Statement Stchar lt char gt Stchar lt char gt Or Stchar none upcase lt string var gt Shell Files Action Sets the character recognized to cause the Action
88. sole Under MicroShell if the user types the command stat gt filename Microshell will redirect the output of stat to the file filename White space blanks or tabs are optional between the gt redirection symbol and the filename Using output redirection the output of any program which runs under CP M may be captured in a file for later use editing printing etc Creating documentation for a program is now much easier and more accurate since the exact screen output can be saved in a file for later incorporation into a manual Or consider the problems of debugging a program which sends special characters to the CRT e g cursor positioning screen clear etc It s often hard to tell what s happening if the wrong special characters are being sent With MicroShell just redirect the output to a file and then look at the file with an editor or DDT to see what characters were sent 2 5 1 Appending Output to a File To append output to an existing file a modification of the basic output redirection function is also provided If a user desires to place the output from a program at the end of an existing file he types the following command line to MicroShell progname gt gt filename Microshell places the output of the program progname at the end of the file filename White space blanks or tabs are optional between the redirection symbol and the filename The append function is one of the featu
89. sole Command Processor CCP The CCP is the part of CP M which interprets commands by the user and performs the built in functions DIR ERA REN SAVE TYPE and USER The vast majority of user programs word processors compilers accounting programs etc actually overlay the CCP to use its space in memory for their own use Microshell replaces overlays the CP M CCP but does not permit user programs to overlay MicroShell as it must remain present to perform many of its functions All of this action is invisible to the majority of CP M programs which use CP M s design entry points to accomplish their functions Some programs mostly older ones look around inside of CP M to perform some function This is not cricket from a software compatibility and transportability aspect and these programs may not operate properly with MicroShell they also probably won t work under new revisions of CP M See Appendix C for a list of known compatible and incompatible programs Since Microshell overlays the CP M CCP it performs all of the functions that the CCP normally performs The following commands will be executed by MicroShell just as the CP M CCP would execute them xcept as noted CCP Command Action Microshell Differences DIR afn Directory listing s option for SYS files ERA afn Erase file s No warning REN newname oldname Rename a file No alternate separator T
90. ssued the command a stat from disk drive B user area 0 Microshell would immediately look on disk drive A user 0 for sStat com If stat com was not found there Microshell would look for a shell file stat sub on drive A user O If neither stat com nor stat sub were found Microshell would not look further but 30 Automatic Program Search would issue the error message a stat and prompt the user for the next command The user may want to use this feature if different versions of a program exist on two separate drives and the user specifically wants the version on another drive If the user is logged onto disk drive B in user area 1 and issues the command a stat MicroShell will look first on disk drive A in user area 1 for the file Stat com If the program is not found there MicroShell will look in user area 0 on drive A If stat com is not found MicroShell will look on drive A in user area 1 for stat sub and then on drive A user 0 before reporting failure 32 Benefit of Main Command Search This feature may seem complex after reading the above discussion but MicroShell s action is actually simple and logical the user is freed from either prefacing commands with a disk drive or having to have a copy of all programs on every disk and user area The concept of a system disk analogous to UNIX s bin directory is not only feasible but greatly simplifies the whole
91. st con in shell and input files causes C or c changed to 03 next character to be its control equivalent s When first character on a shell file this is a comment line causes line to be treated as a this is a comment too comment ignored Echo redirected Output to Console stat gt filename progl prog2 Return character ready to console sysgen lt script input status calls progl prog2 progl prog2 Separate commands era bak stat ed test lt script 3 Treat arguments with embedded spaces echo This is one argument or tabs as 1 argument and ignore special characters inside quotes Ignore special meaning of next dir gt file character filename gt file Argument substitution in shell copyfile test command files 0 18 if copyfile sub contains pip b a 1 then MicroShell executes pip b a test WordStar like Command Line Editing B 0 mustake ST Redirect Input back to console ina ddt lt ST St shell file SP Redirect Output to Printer dir gt S P Sp Intro 3 Introduction Summary of Microshell Commands Cont Shell Flags Flag Meaning Example f or F Auxiliary fil search enabl B O F Default Auxiliary file search on f or F Auxiliary file search disable B O F Auxiliary file search off g or G Gobble lin
92. t of Flags T Transparency Character Flag Off U Upper case command line On V Verbose mode command echo On X eXit MicroShell to CP M Default values with indicates Flag performs action only and has no state 2 4 1 Issuing a Flag Command A Flag command is issued as a normal command to MicroShell either on initial startup or in response to the Microshell prompt or in a shell file or as one of multiple semicolon separated commands on a line The Flag is preceded by a or a depending on whether the user wants to turn the feature on or off Flags may be issued in upper or lower case 10 Automatic Program Search For example A O F lt carriage return gt turns off the automatic file search feature while A O V lt carriage return gt turns the Verbose mode on If there is not an On Off unction associated with a Flag as with the S17 status report Flag either a or a may precede the Flag The following command line is legal A O V L U S lt carriage return gt and would turn on the Verbose Mode login all disks again turn 9ff Upper case command line translation and print a status report of the new Flag conditions 2 4 2 D Flags Delays Default 0 The Delay Flags provide a method for specifying some built in delays in MicroShell There are 4 delays Their syntax meaning and range are Syntax Delay Set Range of Delay D 1 NNN Input Character Dela
93. t took each character of a file did something with it and passed it on to the output This type of program is called a filter and is frequently used in the UNIX environment If you want MicroShell to do the file handling for you redirecting input and output so you can write a simple keyboard to screen filter then you don t want MicroShell eating up the linefeeds So after all this explanation MicroShell has a Flag to selectively gobble linefeeds on single character input you choose Note that MicroShell always gobbles a linefeed after a carriage return when a program asks for a line of input characters you can t change that and probably wouldn t want to To try to solve this nuisance for a part of the cases which might occur MicroShell automatically sets some Flags when a pipe is invoked See Section 2 7 1 for a discussion of how this works If you find you want the Gobble Flag off most of the time if you re using filters a lot with input redirection instead of editor scripts you can change the default using SHSAVE See Section 5 1 Also remember that you can make up a shell file which sets this Flag xecutes some command and then restores the Flag 2 4 5 L Flag Login Disks The L Flag is provided to login a new disk if disks are changed after MicroShell is started If a disk is changed after MicroShell has accessed it once then CP M logs the disk as Read Only and any attempt to write on the disk will r
94. te in the file control block to reflect the drive the file was found on 4 If after looking down the search path for the file MicroShell cannot locate it MicroShell returns control to the user program with the normal CP M open failur code Th user program will then proceed to do whatever it does when it can t find the file 3 4 Benefit of Automatic File Search The benefits which MicroShell provides with the file search feature are similar to those of the main command search the user does not need to be concerned with where all the files that a program needs are located He merely xecutes th programs as if all the necessary files were on the 32 Automatic Program Search current disk drive and user area and MicroShell handles the tedium of locating the files 3415 Some Practical Applications 1 One popular word processing program Wordstar needs to access two overlay ovr files for normal operation Though Wordstar permits one disk drive other than the current drive to be searched for these files no check across user areas is supported Under MicroShell the overlay files may be on the system disk and MicroShell will find them for Wordstar from any user number or disk drive 2 Many Chasic application programs chain to subsequent int files from a main menu program MicroShell can supervise this chaining process and permit all int files to be kept on the system disk
95. th other Programs Compatible Programs Many popular CP M compatible programs have been run under MicroShell with satisfactory operation The following is a partial list Ts CP M utilities ASM DDT ED LOAD STAT PIP SYSGEN 2 Assemblers MAC ACT 80 ACT 86 34 Word Processors Wordstar Spellstar Benchmark Spellbinder Mince 4 Languages BDS C CBASIC II BASCOM PASCAL M 5u Apple CP M with Microsoft Softcard Incompatible Programs Programs which are incompatible with MicroShell are usually accessing information inside of CP M rather than using the normal CP M entry points MicroShell depends on a program using the normal entry points for CP M the BDOS entry point at location 5 and the warm start entry point at location O The following programs are known to be incompatible with MicroShell 1 CP M utilities MOVCPM Requires that the CP M CCP be present Exit MicroShell to do MOVCPM UBMIT MicroShell provides a capability equivalent to the CP M UBMIT function SUBMIT itself requires that the CP M CCP be resent A useful feature is described in Section 4 for having icroShell create a submit file and then exit to CP M to execute he submit file This permits long programs which require all of he computer s memory to be started from MicroShell and icroShell reloaded automatically on completion of the program sett ZO NWN 23 CP M User Group Programs Some of the earlier util
96. the input file Thes ar typically filters programs which read a stream of characters performing some action on them and then exit at the end of the input stream UNICA is an example In the UNIX mode when Microshell detects the end of the input file a control Z or no more sectors in the file a control Z followed by a carriage return is passed to the program The program must recognize the control Z carriage return and then terminate by one of the methods discussed in Section 2 6 2 If the program calls for more input after MicroShell has sent the control Z carriage return MicroShell will force an exit from the program 14 Automatic Program Search The Mode Flag is normally set automatically by MicroShell to the UNIX mode when a pipe is invoked See Section 2 7 1 for a discussion of MicroShell s setting of the Flags for a pipe and Section 5 2 for how to override the automatic setting feature 2 4 7 P Flag Prompt Change Default A 0 The P Flag permits the MicroShell prompt to be changed from within MicroShell The following are examples of possible prompts A O default Drive A User 0 gt A O bell bell sounds after prompt On Drive A User 0 Wordy but possible Enter command The flexibility for setting the prompt to match the user s needs is available Short prompts for experienced users long for occasional users bells for users who do something else while their programs run
97. tion but not placed in the redirected output stream This is useful when running shell files to see that argument substitution is occurring as intended If you are attempting to capture a program s output into a file to create the program documentation for example then the Verbose Flag should be ON If you re running a filter which reads its input and writes out characters then you probably don t want the Verbose Flag on or your input will be mixed with the output in the output stream Microshell automatically handles turning OFF the Verbose Flag when a pipe is invoked by the user unless overridden S Section 2 7 1 2 4 12 X Flag eXit MicroShell The X Flag permits the user to exit Microshell back to CP M A warm start of CP M occurs leaving the user at the CP M prompt Any multiple commands following a x on a line are ignored See Section 4 8 on shell files for a method of exiting Microshell to execute a CP M command and then automatically reloading MicroShell This is useful for running large programs which need the space used by MicroShell 18 Automatic Program Search 26D Output Redirection Output redirection is the process of redirecting a program s output from the console i e the user s terminal to a file This capability is one of the UNIX features which Microshell provides For xample th CP M command stat would normally send the CP M utility stat output to the con
98. ude a UNIX like shell and give the appearance of running UNIX without losing compatibility with the native operating system or requiring the development of a whole new operating system for the VAX The idea was born Why not develop a Shell to lie on top of CP M And in the spring of 1981 MicroShell was thus conceived MicroShell Design It was decided to implement the best functional features of the UNIX shell in MicroShell The initial language chosen for development of Micro Shell was Cc the language developed by Bell Labs for writing the UNIX operating system The Software Tools had been developed in RATFOR a structured preprocessor for FORTRAN which resulted in good transportability of the Software Tools from one operating system and computer to another It was decided that the code generated by RATFOR was too large for the limited CP M environment In addition transportability was a secondary goal So BDS C was chosen as MicroShell s language By June 1981 MicroShell in C was up and running and in daily use with CP M At 12K MicroShell still was larger than desired So a rewrite of portions of MicroShell into assembly language was begu_ The current version of MicroShell is written entirely in assembly language and requires about 8K bytes Overlays are used for functions which are not time sensitive This has allowed expanded error messages xtended shell functions and command line
99. umber in parentheses The user may customize the prompt as desired S Section 2 4 7 The initial command line may be any legal Microshell command For example if the user wanted to log onto drive B immediately he could execute Microshell with the following command line sh b Microshell would then change the default drive to B prior to displaying the initial prompt If a user desired to set some of the shell Flags Section 2 4 on initial entry a shell file Section 4 could be executed on initial entry to perform these functions If the file init sub contained the following lines V b dir Automatic Program Search then by typing sh init MicroShell would turn off the Verbose Flag Section 2 4 11 change the default drive to B and display the directory prior to issuing the initial prompt The shell Flags and shell files are fully described in Sections 2 4 and 4 respectively Before we proceed to discuss MicroShell s other features here s how you get out of MicroShell and back to CP M Just type the x or X exit shell Flag by itself in response to the Microshell prompt Microshell will exit back to CP M and CP M will display its prompt for the current drive e g A O x lt user types x carriage return A gt lt CP M prompt 222 CP M like Functions MicroShell on initial entry relocates itself just below the CP M Basic Disk Operating System BDOS replacing the CP M Con
100. will properly determine disk density within MicroShell Control C typed at the Microshell command prompt is identical to issuing the L Flag If you change disks and forget to log in the new disk before issuing some command you may get a BDOS error Just respond with a Control C Microshell will login the disk and you can execute the command again with the command line editing feature S Section 2 8 2 4 6 M Flag Mode at End of File Default CP M The Mode Flag determines what happens when th nd of an input file is reached when using input redirection reading input from a shell file or using a pipe If the Mode Flag is set for CP M mode M input will revert to the keyboard after all characters have been used from the input file as would happen if a CP M SUBMIT file with XSUB was used under CP M Normal operation of the program from the keyboard then continues This is an excellent way to give a program some initial commands and then enter an interactive mode With WordStar for example the initial commands could set up various WordStar features such as margins and then allow the user to have control of the input There is even a provision made to take some input from an input file shift the input to the keyboard and then shift back to the input file See Section 4 9 4 The UNIX setting of the Mode Flag M is designed for use with programs which expect a control Z followed by a carriage return at the end of
101. y 0 999 tenths of second D 2 NNN Input Line Delay 0 999 tenths of seconds D 3 NNN Output Prompt Delay 0 999 tenths of seconds D 4 NNNNN Input Ignore Factor 0 65535 factor The first 3 delays are in 0 1 seconds i e a setting of 100 will provide a delay of approximately 10 seconds The input delays affect character and line inputs respectively from an input or shell file Their purpose is to permit slowing down a self running demonstration created with MicroShell by inserting a delay whenever the program asks for input The third delay is executed just before MicroShell displays the command prompt It is provided mainly for one situation Heath Zenith computer users using the PIE editor Apparently the PIE editor issues a terminal reset command on exiting which does not have time to complete resetting the terminal before MicroShell tries to display the prompt The result is that several characters from the prompt string are lost before the terminal is ready to accept characters again Setting this delay to 1 will solve the problem The fourth and final delay is the Input Ignore Delay Its use is rather involved If input is redirected to a program which does a lot of things between getting characters it is possible for MicroShell to send characters to the program so fast that the program never has a chance to do whatever it s supposed to do It spends all its time getting characters In some cases the program s input buffer i

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