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FLEX Advanced Programmer`s Manual

1. follows If called with a Drive Number in the FCB of hex FF the function will return with 0 as the drive number in the FCB If called with a 0 it will return with the drive number set to 1 In both cases the carry is cleared on return If called with a drive number of 1 or higher the drive number 15 left unchanged the carry bit is set on return and error 16 Drives Not Ready is set 35 FLEX Advanced Programmer s Guide Function 21 15 hex Position to Record N This is one of the 2 function codes provided for random file accessing by sector The desired record number to be accessed should be stored in the FCB location Current Record Number 16 bit binary value The file must be open for read or update before using this function code The first data record of a file is record number one Positioning to record 0 will read in the first sector of the File Sector Map After successful Position operation the first character read with a sequential read will be the first data byte of the specified record attempt to position to nonexistent record will cause an error For more information on random files see the section titled Random Files Example To position to record 6 LDX FCB Point to FCB LDA 6 Set position STA 33 Put in FCB CLR 32 X Set M S B to 0 LDA 21 Setup function code STA 0 Store in FCB JSR FMS Call FMS BNE ERROR Check for errors Record ready to be read Function 22 0A hex Back
2. user should normally not need to access the directory Function 7 Get Information Record This function should only be issued on an FCB which has been opened with the Open Directory funcion Each time the Get Information Record function is issued the next directory entry will be loaded into the Directory Information area of the FCB see Description of the FCB for details of the format of a directory entry All directory entries including deleted and unused entries when using this function After an entry has been read the FCB is said to point to the directory entry just read the Current Directory Address bytes in the FCB refer to the entry just read An End of File error is returned when the end of the directory is reached Example To get the 3rd directory entry LDX FCB Point to the FCB LDA DRIVE Get the drive number 3 Store in the FCB LDA 6 Setup open dir code STA 0 Store in FCB JSR FMS Call FMS BNE ERROR Check for errors LDB 3 Set counter to 3 LOOP LDA 7 Setup get rec code STA 0 Store in FCB JSR FMS Call FMS BNE ERROR Check for errors DECB Decrement the counter BNE LOOP Repeat til finished The 3rd entry is now in the FCB 31 FLEX Advanced Programmer s Guide Function 8 Put Information Record This function should only be issued on an FCB which has been opened with the Open Directory function The directory information is copied from the Directory Information por
3. The character is returned to the calling program in the A register The Current Line Number location is cleared by a call to GETCHR Because this routine honors the TTYSET parameters its use is preferred to that of INCH If the location Input Switch is non zero the routine INCH2 will be used for input If zero the byte at File Input Address is checked If it is non zero the address at this location is used as a File Control Block of a previously opened input file and a character is retrieved from the file If zero a character is retrieved via the INCH routine The X and B registers are preserved FLEX Advanced Programmer s Guide CD18 PUTCHR Put Character This routine outputs a character to a device honoring all of the TTYSET parameters On entry the character should be the A register If the Special I O Flag see Memory Map is zero the column count is checked and a new line is started if the current line is full If an ACIA is being used to control the monitor terminal it is checked for a TTYSET Escape Character having been typed If so output will pause at the end of the current line If the location Output Switch is non zero the routine OUTCH2 is used to send the character If zero the location File Output Address is checked If it is non zero the contents of this location is used as a address of a File Control Block of a previously opened for write file and the character is written to the file If zero the
4. character from paper tape The INCH2 address should never be altered The Warmstart Entry Point resets the INCH jump vector to the same routine as INCH2 and sets the Input Switch to zero RSTRIO also resets these bytes User programs should use the GETCHR routine documented below rather than calling INCH because INCH does not check the TTYSET parameters CDOF OUTCH Output Character CD12 OUTCH2 Output Character On entry to each of these routines the A register should contain the character b Both of these routines output the character in the A register to an output device The OUTCH routine usually does the same as OUTCH2 however OUTCH may be changed by programs to refer to some other output routine For example OUTCH may be changed to drive a line printer OUTCH2 is never changed and always points to the output routine in the Custom I 0 package This address may not be patched to refer to some other output routine The routine PUTCHR documented below calls one of these two routines depending on the content of the location Output Switch see Memory Map The Warmstart Entry Point resets the OUTCH jump vector to the same routine as OUTCH2 and sets the Output Switch to zero RSTRIO also resets these locations User routines should use PUTCHR rather than calling OUTCH or OUTCH2 directly since these latter two do not check the TTYSET parameters CD15 GETCHR Get Character This routine gets a single character from the keyboard
5. disk may become fragmented Fragmentation results in the sectors on the disk becoming out of order physically even though logically they are still all sequential This is characteristic of linked list structures and dynamic file allocation methods The user need not be concerned with this fragmentation but should be aware of the fact that files may exist whose sectors seem to be spattered all over the disk The only result of fragmentation is the slowing down of file read times because of the increased number of head seeks necessary while reading the file 21 FLEX Advanced Programmer s Guide THE FILE CONTROL BLOCK FCB The FCB is the heart of the FLEX File Management System FMS An FCB is a 320 byte long block of RAM in the user s program area which is used by programs to communicate with FMS A separate FCB is needed for each open file After a file has been closed the FCB may be re used to open another file or to perform some other disk function such as Delete or Rename An FCB may be placed anywhere in the user s program area except page zero that the programmer wishes The memory reserved for use as an FCB need not be preset or initialized in any way Only the parameters necessary to p the function need be stored in the FCB the File Management System will initialize those areas of the FCB needed for its use In the following description of an FCB the byte numbers are relative to the beginning of the FCB i e byte
6. entry point of binary program The format of a transfer address is as follows Byte 0 Transfer Address Indicator 16 ASCII ACK Byte 1 Most significant byte of the transfer address Byte 2 Least significant byte of the transfer address If a file contains more than one transfer address record caused by appending binary files which contain transfer addresses the last one encountered by the load process is the one that is used the others are ignored When reading or writing a binary file through the File Management System from a user program the calling program must process the record indicator bytes and load addresses itself FLEX does not supply or process this information for the user 45 FLEX Advanced Programmer s Guide DESCRIPTION OF A TEXT FILE A text file also called an ASCII file or coded file contains only printable ASCII characters plus few special purpose control charactres There is no load address associated with a FLEX text file as there is with FLEX binary files It is the responsibility of the program which is reading the text file to put the data where it belongs The only control character which FLEX recognizes and processes in a FLEX text file are 00 ASCII CR or RETURN This character is used to mark the end of a line or record the file 00 ASCII NULL Ignored by FLEX if encountered in the file it is not returned to the calling program 18 ASCII CANCEL Ignored by F
7. example assumes the Line Buffer Pointer is pointing to the first character of a file specification and the desired resulting file spec should default to a TXT extension LDX FCB Point to FCB JSR GETFIL Get file spec into FCB BCS ERROR Report error if one LDA 1 Set extension code TXT JSR SETEXT Set the default extension The user open the file for the desired action since the file spec is correctly set up in the FCB Refer to the FMS examples for opening files 2 The following examples demonstrate some simple uses of the basic 1 0 functions provided by DOS LDA A Setup an ASCII A JSR PUTCHR Call DOS out character LDX STRING Point to string JSR PSTRNG Print CR amp LF string The above simple routines are to show the basic mechanism for calling and using DOS 1 0 routines 219 2 FLEX Advanced Programmer s Guide 20 FLEX Advanced Programmer s Guide THE FILE MANAGEMENT SYSTEM The File Management System FMS forms the communication link between the DOS and the actual Disk Hardware FMS performs all file allocation and removal on the disk All file space 15 allocated dynamically and the space used by files is immediately reusable upon that file s deletion The user of the FMS need not be concerned with the actual location of a file on the disk or how many sectors it requires Communication with the FMS is done through File Control Blocks These blocks contain the information about a fil
8. extreme care in its use This function is normally used internally by FLEX and user program should never need to use it The Read Write Next Byte function should be used whenever possible Careless use of the Write Single Sector function may result in the destruction of data necessitating the re initialization of the diskette The disk address being written is taken from the Current Position bytes of the FCB the data is taken from the FCB Sector Buffer This function honors the Verify Flag see Global Variables section for a description of the Verify Flag and will check the sector after writing it if directed to do so by the Verify Flag 32 FLEX Advanced Programmer s Guide Function 11 0B hex Reserved for future system use Function 12 0C hex Delete File This function deletes the file whose specification is the FCB drive numbers file name and extension The sectors used by the file are released to the system for re use The file should not be open when this function is issued The file specification in the FCB is altered during the delete process Example LDX FCB Point to FCB setup file spec in FCB LDA 12 Setup function code STA 0 Store in FCB JSR FMS Call FMS BNE ERROR Check for errors File has now been deleted Function 13 0D hex Rename File On entry the file must not be open the old name must be the File Specification area of the FCB and the new name and extension must be i
9. function are the file specification parts drive number file name and file extension and the function code The remaining parts of the FCB will be initialized by the Open process The Open process sets the File Compression Mode Flag to zero indicating text file If the file is binary the programmer should set the File Compression Mode Flag to FF after opening the file to disable the space compression feature On exit from FMS after opening a file the function code in the FCB is automatically set to zero Read Write Next Byte Function in anticipation of I 0 on the file Example LDX FCB Point to the FCB Set up file spec in FCB LDA 1 Set open function mode STA 0 Store in FCB JSR FMS Call FMS BNE ERROR Check for errors The file is now open for text reading To set for binary continue with the following LDA FF Set FF for sup flag STA 59 X Store in suppression flag Function 2 Open for Write This is the same as Function 1 Open For Read except that the file must not already exist in the diskette directory and it is opened for write only access file opened for write may not be read unless it is first closed and then re opened for read only The space compression flag should be treated the same as described in Open for Read A file is normally opened as a sequential file but may be created as a random file by setting the FCB location File Sector Map byte non zero immediately following an open for write o
10. program is later executed it simply takes this disk address and loads the binary file which resides at that location The load process is terminated upon the receipt of a transfer address record At this time control is transferred to the proqram just loaded by jumping to the address specified in the transfer address record If the linked program is ever moved on the disk then it must be re linked so the boot knows the new disk address LINK may be used in some specialized applications One is the development of custom operating systems The user may write his own operating system link it to the boot and use it exactly as FLEX is used now It may also be desirable for special disks to boot in specialized programs rather than the operating system If this is done remember that unless the DOS is loaded during the boot process there will not be any disk drivers or File Management System resident in memory 51 FLEX Advanced Programmer s Guide 2595 FLEX Advanced Programmer s Guide PRINTER ROUTINES There are two printer related programs provided with FLEX One is the P Utility the other is the PRINT SYS file which is the actual set of printer drivers initialize printer and output character command source listing is provided on the following pages and should self explanatory Below you will find the requirements of the PRINT SYS file No source listing is provided here since one 15 given in the FLEX User s Manu
11. routine OUTCH is called to process the character Normally OUTCH sends the character to the terminal The user program may however change the address portion of the OUTCH entry point to go to another character output routine The X and B registers are preserved CD1B INBUFF Input into Line Buffer This routine inputs a line from the keyboard into the Line Buffer The TTYSET Backspace and Delete characters are checked and processed if encountered 11 other control characters except RETURN and LINE FEED are ignored The RETURN is placed the buffer at the end of the line A LINE FEED is entered into the buffer as a space character but is echoed back to the terminal as a Carriage Return and Line Feed pair for continuation of the text on new line At most 128 characters may be entered on the line including the final RETURN If more are entered only the first 127 are kept the RETURN being the 128th On exit the Line Buffer Pointer is pointing to the first character in the Line Buffer Caution The command line entered from the keyboard is kept in the Line Buffer Calling INBUFF from a user program will destroy the command line including all unprocessed commands on the same line Using INBUFF and the Line Buffer for other than DOS commands may result in unpredictable side effects CDIE PSTRNG Print String This routine is similar to the PDATA routine in SWTBUG and DISKBUG On entry the X register should contain the address of
12. the first character of the string to be printed The string must end with an ASCII EOT character 04 This routine honors all of the TTYSET conventions when printing the string A carriage return and line feed are output before the string The B register are preserved 210 FLEX Advanced Programmer s Guide CD21 CLASS Classify Character This routine is used for testing if a character is alphanumeric i e a letter or a number On entry the character should be the A register If the character is alphanumeric the routine returns with the carry flag cleared If the character is not alphanumeric the carry flag is set and the character is stored in the Last Terminator location All registers are preserved by this routine CD24 PCRLF Print Carriage Return and Line Feed In addition to printing a carriage return and line feed this routine checks and honors several TTYSET conditions On entry this routine checks for TTYSET Escape Character having been entered while the previous line was being printed If so the routine waits for another TTYSET Escape Character a RETURN to be typed If a RETURN was entered the routine clears the Last Termi location so as to ignore any commands remaining in the command line and then jumps to the address contained in the Escape Return Register locations Unless changed by the user s program this address is that of the Warmstart Entry Point If instead of a RETURN another TTYSET Escape Chara
13. 0 is the first byte of the FCB DESCRIPTION OF AN FCB Byte 0 Function Code The desired function code must be stored in this byte by the user before calling FMS to process the FCB See the section describing FMS Function Codes Byte 1 Error Status Byte If an error was detected during the processing of a function FMS stores the error number in this byte and returns to the user with the CPU Z Condition Code bit clear i e a non zero condition exists This may be tested by the BEQ or BNE instruction Byte 2 Activity Status This byte is set by FMS to a 1 if the file is open for read or 2 if the file is open for writing This byte is checked by several FMS function processors to determine if the requested operation is legal A Status Error is returned for illegal operations The next 12 bytes 3 14 comprise the File Specification of the file being referenced by the FCB A File Specification consists of a drive number file name and file extension Some of the FMS functions do not require the file name or extension See the documentation of the individual function codes for details Byte 3 Drive Number This is the hardware drive number whose diskette contains the file being referenced It should be binary 0 to 3 290 FLEX Advanced Programmer s Guide The next 24 bytes 4 27 comprise the Directory Information portion of the FCB This is the exact same information which is contained the diskette directory entry
14. 15 P25 P3 P4 P8 NOPST ERSTR c JMP LDA CMPA BNE LEAX JSR BRA JSR JSR JMP LEAX BRA FCC FCB FCC FCB FLEX Advanced Programmer s Guide POUT 39 P15 P2 FF 59 LOAD PINIT POUT OUTCH L RENTER 1 X NFER NOPST PCR PSTRNG P4 RPTERR FMSCLS WARMS ERSTR PCR P25 GET 1ST BYTE OF SPACE IS IT RTS IF NOT THEN LOADED POINT TO FCB OPEN FILE FOR READ CALL FMS CHECK FOR ERRORS SET FOR BINARY READ SET COMPRESSION FLAG CALL FLEX S LOADER GO INITIALIZE PORT GET OUTPUT ADDRESS STUFF IN FLEX RETURN TO FLEX GET ERROR CODE IS IT NO SUCH FILE POINT TO MESSAGE GO PRINT IT REPORT ERROR CLOSE ALL FILES RETURN TO FLEX POINT TO STRING GO PRINT IT PRINT SYS NOT FOUND 4 P MUST BE FOLLOWED BY A COMMAND 4 THE FOLLOWING CODE IS LOADED INTO THE SYSTEM FCB WHEN THE P COMMAND IS LOADED INTO MEMORY IT PRESETS THE FILE NAME IN THE FCB ORG FCB FCC FCB FEE END 55 C843 FF PRINT 0 0 0 Sys P FLEX Advanced Programmer s Guide 56 FLEX Advanced Programmer s Guide INTERRUPTS IN FLEX FLEX makes extensive use of interrupts during printer spooling Anytime there are files in the PRINT Queue as a result of using the PRINT command the timer board MP T in 1 0 slot 4 is activated This board is initialized to output interrupts every 10 milliseconds These are IRQ type interrupts and FLEX sets the IRQ vector
15. CB that is already open 3 THE FILE SPECIFIED ALREADY EXISTS a An Open For Write was issued on an FCB containing the specifiaction for a file already existing in the diskette directory b A Rename function was issued specifying a new name that was the same as the name of a file already existing in the diskette directory 4 THE SPECIFIED FILE COULD NOT BE FOUND An Open for Read or Update a Rename or a Delete function was requested on FCB containing the file specification for file which does not exist in the diskette directory 5 SYSTEM DIRECTORY ERROR REBOOT SYSTEM Reserved for future system use 6 THE SYSTEM DIRECTORY SPACE IS FULL This error should never occur since the directory space is self expanding and can never be filled Only disk space can be filled error 7 7 ALL AVAILABLE DISK SPACE HAS BEEN USED All of the available space the diskette has been used up by files If this error is returned by FMS the last character sent to be written to a file did not actually get written 8 READ PAST END OF FILE A read operation on a file encountered an end of file All of the data in the file has been processed This error will also be returned when reading a directory whth the Get Information Record function when the end of directory is reached 9 DISK FILE READ ERROR A checksum error was encountered by the hardware in attempting to read a sector DOS has already attempted to re read the failing sect
16. D extension or they may be memory resident in either RAM or ROM MEMORY RESIDENT COMMANDS A memory resident command is a program already in memory to which DOS will transfer when the proper command is entered from the keyboard The command which invokes the program and the entry point of the program are stored in a User Command Table created by the programmer in memory Each entry in the User Command Table has the following format command Name that will invoke the program FCB 0 FDB entry address entry address of the program The entire table is ended by a zero byte For example the following table contains the commands DEBUG entry at 3000 and PUNT entry at 3200 FCC DEBUG Command Name FCB 0 FDB 3000 Entry Address for DEBUG PUNT Command name FCB 0 FDB 3200 Entry address for PUNT FCB 0 End of Command table The address of the User Command Table is made known to DOS by storing it in the User Command Table Address locations see Memory Map The User Command Table is searched before the disk directory but after DOS s own command table is searched The DOS command table contains only the GET and MON commands Therefore the user may not define his own GET and MON commands Since the User Command Table is searched before the disk directory the programmer may have commands with the same name as those on the disk However in this case the commands the disk will never be executed w
17. FLEX Programmer s Manual Technical Systems Consultants Inc FLEX Programmer s Manual Copyright C 1979 by TECHNICAL SYSTEMS CONSULTANTS INC 0 Box 2574 West Lafayette Indiana 47906 All Rights Reserved COPYRIGHT NOTICE The FLEX Operating System and all of its associated documentation are provided for personal use and enjoyment by the purchaser entire program and all documentation including this manual are copyrighted by Technical Systems Consultants Inc and reproduction by any means is strictly prohibited Use of the FLEX Operating System and or its documentation or any part thereof for any purpose other than single end use is strictly prohibited FLEXIMis a trademark of Technical Systems Consultants Inc Lig I5 II III IV VI VII VIII IX CONTENTS Introduction Disk Operating System DOS Memory Map User Callable Routines User Written Commands Disk Resident Commands Comments about Commands Examples of DOS Calls File Management System File Control Blocks FMS Entry Points FMS Global Variables Random Files Error Numbers Disk Drivers Disk Structures Diskette Initialization Directory Sectors Data Sectors Binary Files Text Files Writing Utility Commands Example Program The DOS LINK Utility Printer Routines The P Utility General Information Interrupts in Flex System Memory Map 41 43 43 44 44 46 47 49 49 Pre
18. FMS when looking for free entry in the directory to which to assign the name of a new file Bytes 53 63 Scratch Bytes Byte These are the bytes into which the user stores the new name and extension of a file being renamed The new name is formatted the same as described above under File Name and File Extension 59 Space Compression Flag If a file is open for read or write this byte indicates if space compression is being performed A value of zero indicates that space compression is to be done when reading or writing the data This is the value that is stored by the Open For Read and Open for Write functions A value of FF indicates that space compression is to be done This value is what the user must store in this byte after opening the file if space compression is not desired Such as for binary files A positive non zero value in this byte indicates that space compression 15 currently in progress the value being a count of the number of spaces processed thus far Note that although this byte overlaps the Scratch Bytes described above there is no conflict since the Space Compression Flag 15 used only when a file is open and the Scratch Bytes are used only by Rename which requires that the file be closed In general this byte should be 0 while working with text type files and FF for binary files Bytes 64 319 Sector Buffer These bytes contain the data contained in the sector being read or written The first four
19. LEX if encountered in the file it is not returned to the calling program 09 ASCII HT or HORIZONTAL TAB This is flag character which indicates that a string of spaces has been removed space saving measure The next byte following the flag character is a count of the number of spaces removed 2 127 The calling program sees neither the flag character not the count character The proper number of spaces are returned to the user program as successive characters are requested by the Read Next Byte function When writing a file the spaces are automatically deleted as the user program sends them to the File Management System using the Write Next Byte function The data compression is therefore transparent to the calling program The above discussion 15 only valid if the file is open for Text operations If open for Binary the compression flag and count get passed exactly as they appear in the file 46 FLEX Advanced Programmer s Guide WRITING UTILITY COMMANDS Utility commands are best prepared by the use of an assembler FLEX reserves a block of memory in which medium size utilities may be placed This memory start s at hex location C100 and extends through location C6FF The system FCB at location C840 may also be used in user written utilities for either FCB space or temporary storage No actual code should reside in this FCB space since it would interfere with the loading of the utility FLEX is using that FCB while lo
20. NBUF will interpret as the line cancel or Delete character It is user definable through the 5 DOS Utility Default 18 Ctrl X ASCII CAN 02 TTYSET End of Line Character This is the character DOS recognizes as the multiple command per line separator It is user definable through the TTYSET Utility Default 3A a colon CC03 TTYSET Depth Count This byte determins how many lines DOS will print on a page before Pausing or issuing Ejects It may be set by the user with the TTYSET command Default 0 CCO4 TTYSET Width Count This byte tells DOS how many characters to output on each line If zero there is no limit to the number output This count may be set by the user using TTYSET Default 0 3 FLEX Advanced Programmer s Guide 05 TTYSET Null Count This byte informs DOS if the number of null or pad characters to be output after each carriage return line feed pair This count maybe set using TTYSET Default 4 CCO6 TTYSET Tab Character This byte defines a tab character which may be used by other programs such as the Editor DOS itself does not make use of the Tab character Default 0 no tab character defined 07 TTYSET Backspace Echo Character This is the character the routine INBUF will echo upon the receipt of a backspace character If the backspace echo character is set to a 08 and the backspace character is also a 08 FLEX will output a space 20 prior to the output
21. ST9 LDA STA 0 JSR SETEXT JSR FMS BNE LIST9 LIST4 LDX FCB JSR FMS BNE LIST6 CMPA D BNE LIST5 JSR PCRLF BRA LIST4 LIST5 JSR PUTCHR BRA LIST4 249 DOS WARMS START ENTRY GET FILE SPECIFICATION PUT CHARACTER ROUTINE PRINT CR amp LF SET DEFAULT NAME EXT REPORT DISK ERROR SYSTEM FCB GET AROUND TEMPS VERSION NUMBER POINT TO FCB GET FILE SPEC ANY ERRORS SET UP CODE SAVE FOR READ OPEN SET TXT EXTENSION CALL FMS DO OPEN CHECK FOR ERROR POINT TO FCB CALL FMS GET CHAR ERRORS IS CHAR A CR OUTPUT CR amp LF REPEAT OUTPUT THE CHARACTER REPEAT SEQUENCE FLEX C12D C12F C131 C133 C135 Clay C13A C13C C13F C142 C145 Advanced Programmer s Guide LIST6 LIST9 50 1 8 LIST9 4 0 X FMS LEST9 WARMS RPTERR FMSCLS WARMS LIST GET ERROR STATUS IS IT EOF ERROR CLOSE FILE CODE STORE IN FCB CALL FMS CLOSE FILE ERRORS RETURN TO FLEX REPORT ERROR CLOSE ALL FILES RETURN TO FLEX FLEX Advanced Programmer s Guide THE DOS LINK UTILITY The LINK Utility provided with FLEX is a special purpose command Its only function is to inform the disk boot which is on track 0 where the program resides which is to be loaded during the boot operation Normally LINK is used to set the pointer to the DOS program Since DOS may reside anywhere on the disk LINK takes the starting disk address of the file and stores it in a pointer in the boot sector When the boot
22. ading utilities An example will be given to demonstrate some of the conventions and techniques which should be used when writing utilities The example which be found on the following paqes is a simple text file listing utility Its syntax is LIST lt SPEC gt The default extension on the file spec is TXT The utility will simply display the contents of a text file on the terminal line for line The following is a section by section description of the LIST utility The first section of the source listing is a set of EQUATES which tell the assembler where the various DOS routines reside in memory These equates represent the addresses given in this manual for User Callable DOS System Routines The next two sections are also equates the first to the FMS entry points and the second references the system FCB The actual program finally starts with the ORG statement In this program we will make rere the Utility Command space located at C100 therefore the ORG is to 5 100 One of the conventions which should be observed when writing DOS utilities is to always start the program with a BRA instruction Following this instruction should be VN FCB 1 which defines the version number of the utility The 1 should of course be set to whatever the actual version number is In this example the version number is 1 This convention allows the FLEX VERSION Utility to correctly identify the version number of a command Moving
23. al PRINT SYS FILE REQUIREMENTS The PRINT SYS file needs to provide the system with three basic printer routines one for printer port initialization one for printer status and one for output character to printer routine The P routine and the system printer spooler use these routines to communicate with the printer A source listing of the provided routines are included in the FLEX User s Manual and will not be duplicated here The three routines and their requirements are listed here PINIT CCCO CCD7 This routine should initialize the printer port No registers need be preserved PCHK CCD8 CCE3 This routine should check to see if the printer can accept another character Return Negative CC status if can accept Plus if cannot Preserve A B X Y and U POUT CCE4 CCF7 This routine should output the character in A after calling PCHK to verify the printer can accept the character Preserve B X Y and U THE SYSTEM PRINTER SPOOLER FLEX contains a printer spooler module It requires the installation of an interval timer board for operation Essentially the spooler is a multi tasking system with the output to printer function being a low priority task requested disk service will cause the printer task to temporarily halt until the disk has been used It should be noted that the SW13 CPU vector is adjusted in this task scheduler PRINT command 15 used to activate the spooler which in turn prints the files i
24. andom Byte in Sector The file must be open for update This function is similar to Get Random Byte except the character in the accumulator is written into the sector at the data location specified by Random Index of the FCB The Random Index should not be less than 4 since only system data resides in the first 4 bytes of the sector Example To write the 54th data byte of the current sector LDX FCB Point to FCB LDA 25444 Set to item 4 STA 35 X Put it in random index LDA 18 Setup function code STA 0 Store in FCB LDA CHAR Get character to be written JSR FMS Call FMS BNE ERROR Check for errors Character has been written Function 19 13 hex Reserved for future system use Function 20 14 hex Find Next Drive This function is used to find the next online drive which is in the ready state Due to hardware limitations the minifloppy version of FLEX performs this command differently than the full size floppy version The functioning of the full size floppy version is as follows If the drive number in the FCB is hex FF the search for drives will start with drive 0 If the drive number is 0 1 or 2 the search will start with drive 1 2 or 3 respectively Ifa ready drive is found its drive number will be returned the drive number byte of the FCB and the carry bit will be cleared If no ready drive is found the carry bit will be set and error 16 Drives Not Ready is set The minifloppy version functions
25. ar issue TST B before returning to accomplish this FLEX expects status responses as produced by the Western Digital 1771 Controller These statuses must be simulated if some other controller is used All drivers should return with the X Y and registers unchanged All routines are enterd with a JSR instruction DEOO Read Entry X FCB Sector Buffer Address A Track Number B Sector Number The sector referenced by the track and sector numbers is to be read into the Sector Buffer area of the indicated FCB DE03 Write Entry X FCB Sector Buffer Address A Track Number B Sector Number The content of the Sector Buffer area of the indicated FCB is to be written to the sector referenced by the track and sector numbers DEO6 Verify Entry No parameters The sector just written is to be verified to determine if there are CRC errors DEO9 Restore Entry X FCB Address Exit CC amp B B if write protected CS NE amp B F if no drive A Restore Operation also known as a Seek to Track 00 is so performed on the drive whose number is in the FCB 41 FLEX Advanced Programmer s Guide DEOC Drive Select Entry X FCB Address The drive whose number is in the FCB is to be selected DEOF Check Drive Ready Entry X FCB Address Exit NE amp CS if drive not ready EQ amp CC if drive ready This routine is setup for FLEX systems where it is possible to check
26. ber indicating the number of sectors the file 23 FLEX Advanced Programmer s Guide Byte 23 File Sector Map Indicator If this byte is non zero usually 02 the file has been created as a random access file and contains a File Sector Map See the description of Random Files for details Byte 24 Reserved for future system use Bytes 25 27 File Creation Date These three bytes contain the binary date of the files creation The first byte is the month the second is the day and the third is the year only the tens ond ones digits Bytes 28 29 FCB List Pointer All FCBs which are open for reading or writing are chained together These two bytes contain the memory address of the FCB List Pointer bytes of the next FCB in the chain These bytes are zero if this FCB is the last FCB in the chain The first FCB in the chain is pointed to by the FCB Base Pointer See Global Variables Bytes 30 31 Current Position These bytes contain the hardware track and sector numbers respectively of the sector currently in the sector buffer portion of the FCB If the file is being written the sector to which these bytes point has not yet been written to the diskette it is still in the buffer Bytes 32 33 Current Record Number These bytes contain the current logical Record Number of the sector in the FCB buffer Bytes 34 Data Index This byte contains the address of the next data byte to be fetched from if reading or stored into
27. bytes of the sector are used by the system The remaini 252 are used for data storage 25 FLEX Advanced Programmer s Guide FILE MANAGEMENT SYSTEM Entry Points D400 FMS Initialization This entry point is used by the DOS portion of FLEX to initialize the File Management System after a coldstart There should be need for a user written program to use this entry point Executing an FMS Initialization at the wrong time may result the destruction of data files necessitating a re initialization of the diskette D403 FMS Close This entry point is used by the DOS portion of FLEX at the end of each command line to close any files left open by the command processor User written programs may also use this entry point to close all open files however if an error is detected in trying to close a file any remaining files will not be closed Thus the programmer is cautioned against using this routine as a substitute for the good programming practice of closing files individually There are no arguments to this routine It is entered by a JSR instruction as though it were a subroutine On exit the CPU Z Condition code is set if no error was detected i e a zero condition exists If an error was detected the CPU Z Condition code bit is clear and the X register contains the address of the FCB causing the error D406 FMS Call This entry point is used for all other calls to the File Management System A function code is st
28. cter was typed or it wasn t necessary to wait for one the Current Line Number is checked If the last line of the page has been printed and the TTYSET Pause feature is enabled the routine waits for a RETURN or a Escape Character as above Note that all pausing is done before the carriage return and line feed are printed The carriage return and line feed are now printed followed by the number of nulls specified by the TTYSET Null Count If the end of the page was encountered on entry to this routine an eject is performed by issuing additional carriage return line feeds and nulls until the total number of blank lines is that specified in the TTYSET Eject Count The X register is preserved CD27 NXTCH Get Next Buffer Character The character in location Current Character is placed in location Previous Character The character to which the Line Buffer Pointer points is taken from the Line Buffer and saved in the Current Character location Multiple spaces are skipped so that a string of spaces looks no different than a single space The Line Buffer Pointer is advanced to point to the next character unless the character just fetched was a RETURN or TTYSET End Of Line character Thus once an End of Line character or RETURN is encountered additional calls to NXTCH will continue to return the same end of line character or RETURN cannot be used to cross into the next command in the buffer NXTCH exits through the ro
29. d See documentation of these routines for details CC23 Input Switch If zero input performed by GETCHR is through the routine INCH If it is non zero the routine INCH2 is used See documentation of these routines for details CC24 CC25 File Output Address These bytes contain the address of the File Control Block being used for file output If the bytes are zero no file output is performed See PUTCHR description for details These locations are set by RSTRIO CC26 CC27 File Input Address These bytes contain the address of the File Control Block being used for file input If the bytes are zero no file input is performed The routine RSTRIO clears these bytes See GETCHR for details CC28 Command Flag This location is non zero if DOS was called from a user program via the DOCMND entry point See documentation of DOCMND for details CC29 Current Output Column This location contains a count of the number of characters currently in the line being output to the terminal This is compared to the TTYSET Width Count to determine when to start a new line The output of a control character resets this count to zero CC2A System Scratch FLEX Advanced Programmer s Guide CC2B CC2C Memory End These two bytes contain the end of user memory This location is set during system boot and may be read by programs requiring this information CC2D CC2E Error Name Vector If these bytes are zero the routine RPTERR will
30. detecting such a state THE FILE IS PROTECTED ACCESS DENIED Reserved for future system use SYSTEM FILE STATUS ERROR a A read or Rewind was attempted on a file which was closed or open for write access b A write was attempted on a file which was closed or open for read access FMS DATA INDEX RANGE ERROR The Get Random Byte from Sector function was issued with a Random Byte number greater than 256 FMS INACTIVE REBOOT SYSTEM Reserved for future system use ILLEGAL FILE SPECIFICATION A format error was detected in a file name specification The name must begin with a letter and contain only letters digits hyphens and or underscores Similarly with file extensions File names are limited to 8 characters extensions to 3 39 FLEX Advanced Programmer s Guide 22 SYSTEM FILE CLOSE ERROR 23 24 25 26 27 28 Reserved for future system use SECTOR MAP OVERFLOW DISK TOO SEGMENTED An attempt was made to create a very large random access file ona disk which is very segmented All record information could not fit the 2 sectors of the File Sector Map Recreating the file new diskette will solve the problem NON EXISTENT RECORD NUMBER SPECIFIED A record number larger than the last record number of the file was specified in a random position access RECORD NUMBER MATCH ERROR FILE DAMAGED The record located by the FMS random search is not the correct record The file is probably dama
31. down the program to the label called LIST2 the program needs to retrieve the file specification and get it into the FCB Pointing X to the FCB we can make use of the DOS resident subroutine called GETFIL to automatically parse the file spec check for errors and set the name in the FCB correctly If all goes well in GETFIL the carry should be clear otherwise there were errors in the file spec and this fact needs reported If the carry is set control is passed to the line with the label LIST9 At this point the error message is reported and control is returned to FLEX If the file spec was correct and the carry was clear after the return from GETFIL we want to set default file name extension of TXT The DOS subroutine named SETEXT will do exactly that First it is necessary 47 FLEX Advanced Programmer s Guide to put the code for TXT in the A accumulator the code is 1 X needs to be pointing to the FCB which it still is The 1 is also put the FCB for the future open operation The call is made to SETEXT and the file name is now correctly set up in the FCB Note that no errors can be generated by a call to SETEXT Now that we have the file spec it is necessary to open the requested file for read X is still pointing to the FCB so it is not necessary to reset FMS Function Code for open a file for read is 1 which was previously put in the FCB location 0 call to FMS is now made attempt to open
32. e such as its name and what drive it exists on All disk 1 0 performed through FMS is one character at a time I O This means that programs need only send or request a single character at a time while doing file data transfers In effect the disk looks no different than a computer terminal Files may be opened for either reading or writing Any number of files may be opened at any one time as long as each one is assigned its own File Control Block The FMS is a command language whose commands are represented by various numbers called Function Codes Each Function Code tells FMS to perform a specific function such as open a file for read or delete a file In general making use of the various functions which the FMS offers is quite simple The index register is made to point to the File Control Block which is to be used the Function Code is stored in the first byte of the File Control Block and FMS is called as a subroutine JSR At no time does the user ever have to be concerned with where the file is being located on the disk how long it is or where its directory entry is located The FMS does all of this automatically Since the file structure of FLEX is a linked structure and the disk space is allocated dynamically it is possible for a file to exist on the disk in a set of non contiguous sectors Normally if a disk has just been formatted a file will use consecutive sectors on the disk As files are created and deleted however the
33. e contains no data Example LDX FCB Point to the FCB LDA 4 Setup close code STA 0 Store in FCB JSR FMS Call FMS BNE ERROR Check for errors File has now been closed Function 5 Rewind File Only files which have been opened for read may be rewound On exit from FMS the function code in the FCB is set to zero anticipating a read operation on the file If the programmer wishes to rewind a file which is open for writing so that it may now be read the file must first be closed th re opened for reading Example Assuming the file is open for read LDX FCB Point to the FCB LDA 2 Setup rewind code STA 0 Store in FCB JSR FMS Call FMS BNE ERROR Check for errors File is now rewound amp ready for read 30 FLEX Advanced Programmer s Guide Function 6 Open Directory This function opens the directory on the diskette for access by a program The FCB used for this function must not already be open for use by a file On entry the only information which must be preset in the FCB is the drive number no file name 5 required The directory entries are read by using the Get Information Record function The Put Information Record function is used to write a directory entry The normal Read Write Next Byte function will not function correctly on an FCB which is opened for directory access It is not necessary to close an FCB which has been opened for directory access after the directory manipulation is finished The
34. e skipped until a separator character is found then the routine returns to the caller with the carry bit set The number in the Line Buffer may be of any length but the value is truncated to between 0 and FFFF inclusive CD45 OUTADR Output Hexadecimal Address On entry the X register contains the address of the most significant byte of a 2 byte hex value The bytes to which the X register points are printed as 4 hexadecimal digits 14 FLEX Advanced Programmer s Guide CD48 INDEC Input Decimal Number This routine gets an unsigned decimal number from the Line Buffer On entry the Line Buffer Pointer must point to the first character of the number in the Line Buffer On exit the carry bit is cleared if a valid number was found the B register is set non zero and the X register contains the binary value of the number The Line Buffer Pointer is left pointing as described in the routine GETHEX If the first character examined in the buffer is separator character such as a comma the carry bit is still cleared but the B register is set to zero indicating that actual number was found In this case the number returned in X is zero The number in the Line Buffer may be of any length but the result is truncated to 16 bit precision CD4B DOCMND Call DOS as a Subroutine This entry point allows a user written program to pass a command string to DOS for processing and have DOS return control to the user program on compl
35. een called by using the SETEXT routine The Line Buffer Pointer is left pointing to the character immediately beyond the separator unless the separator is a carriage return or End of Line character If an error was detected Error number 21 is stored in the error status byte of the FCB The X register is preserved with a call to this routine CD30 LOAD File Loader On entry the system File Control Block at C840 must contain the name of a file which has been opened for binary reading This routine is used to load binary files only not text files The file is read from the disk and stored in memory normally at the load addresses specified in the binary file itself It is possible to loa file into a different memory area by using the Loader Address Offset locations The 16 bit value in the Loader Address Offset locations is added to the addresses read from the binary file Any carry generated out of the most significant bit of the address is lost The transfer address if any is encountered is not modified by the Loader Address Offset Note that the setting of a value in the Loader Address Offset does not modify any part of the content of the binary file It does not act as program relocator in that it does not change any addresses in the program itself merely the location of the program in memory If the the file is to be loaded without an offset be certain to clear the Loader Address Offset locations before calling this routine On e
36. entary the routines NXTCH and CLASS in the section User Callable System Routines CC12 CC13 User Command Table Address The programmer may store into these locations the address of a command table of his own construction See the section called User Written commands for details Default 0000 no user command table is defined CC14 CC15 Line Buffer Pointer These locations contain the address of the next character in the Line Buffer to be precessed See documentation of the routines INBUFF NXTCH GETFIL GETCHR and DOCMND in the section User Callable System Routines for instances of its use CC16 CC17 Escape Return Register These locations contain the address to which to jump if a RETURN is typed while output has been stopped by an Escape Character See the FLEX User s Guide TTYSET for information on Escape processing See also the documentation for the routine PCRLF in the section User Callable System Routines for details CC18 Current Character This location contains the most recent character taken from the Line Buffer by the NXTCH routine See documentation of the NXTCH routine for additional details CC19 Previous Character This location contains the previous character taken from the Line Buffer by the NXTCH routine See documentation of the NXTCH routine for additional details CC1A Current Line Number This location contains a count of the number of lines currently the page This value i
37. er s Guide GENERAL COMMENTS ABOUT COMMANDS User written commands are entered by JMP instruction On completion they should return control to DOS by jumping JMP instruction to the Warmstart Entry Point see Memory Map Processing Arguments User written commands are required to process any arguments entered from the keyboard The command name and the arguments typed are in the Line Buffer area see Memory Map The Line Buffer Pointer on entry to the command is pointing to the first character of the first argument if one exists If there are no arguments the Line Buffer Pointer is pointing to either an end of line character or a carriage return The last terminator character is the character that followed the name of the command and will normally be a comma a space end of line etc The DOS routines NXTCH GETFIL and GETHEX should be used by the command for processing the arguments Processing Errors If the command while executing receives an error status from either DOS or FMS of such a nature that the command must be aborted the program should jump to the Warmstart Entry Point of DOS after issuing an appropriate error message Similarly if the command should detect an error on its own it should issue a message and return to DOS through the Warmstart Entry Point 18 FLEX Advanced Programmer s Guide EXAMPLES OF USING DOS ROUTINES 1 Setting up a file spec in the FCB can be done the following manner The
38. etion of the commands The command string must be placed in the Line Buffer by the user program and the Line Buffer Pointer must be pointing to the first character of the parameters and commands the Line Buffer The command string must terminate with a RETURN character 0D hex After the commands have been processed DOS will return control to the user s program with the B register containing any error code received from the File Management System The B register will be zero if no programs which may destroy the user program in memory An example of a use of this feature of DOS is that of a program wanting to save a portion of memory as a binary file on the disk The program could build a SAVE command in the Line Buffer with the desired file name and parameters and call the DOCMND entry point On return the memory will have been saved on the disk CD4E STAT Check Terminal Input Status This routine may be called to check the status of the terminal input device to see if a character has been typed on the keyboard If a character has been hit the Z condition code will be cleared on return a not equal condition If no character has been hit the Z condition code will be set an equal condition No registers other than the CC register are altered FLEX Advanced Programmer s Guide USER WRITTEN COMMANDS The programmer may write his own commands for DOS These commands may be either disk resident as disk files with a CM
39. f any in the print queue Exact details of the spooling operation are not available at this time 53 FLEX Advanced Programmer s Guide C100 C100 C102 C103 C106 C108 C10B C10D C10F C111 C114 C116 C118 C11B 110 C840 CD30 D406 D403 CD06 0004 CC09 1 CD3F CD03 11 CC02 CCCO CCE4 COOF CCFC 01 Xx P UTILITY COMMAND COPYRIGHT C 1979 BY THE P COMMAND INITIALIZES A PORT AND CHANGES THE OUTCH JUMP VECTOR IN FLEX TECHNICAL SYSTEMS CONSULTANTS INC EQUATES FCB LOAD FMS FMSCLS RENTER NFER PAUSE PSTRNG RPTERR WARMS LSTTRM EOL PINIT POUT OUTCH PR1 VN P12 EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU CLR C840 CD30 D406 D403 CD06 4 CC09 CDIE CD3F CD03 CC11 SCCO2 CCCO CCE4 CDOF CCFC C100 PT 1 P12 FCB 27 1 X P3 LSTTRM D P8 EOL P8 PAUSE continued 54 BRANCH AROUND TEMPS VERSION NUMBER CHECK SYSTEM PROCESS REG IS IT BUSY POINT TO FCB SET BUSY ERROR STUFF IN FCB GO REPORT ERROR GET LAST TERMINATOR IS IT A CR IS IT EOL CHARACTER DISABLE THE PAUSE FEATURE C120 C123 C125 C127 C12A C12C 12 C131 C133 C135 C138 C13B C13E C141 C144 C147 C149 C14B C14D C151 C154 C156 C159 C15C C15F C163 C165 C17A C17B C19C C843 C843 C844 C849 C84C FF 50 00 53 52 49 00 00 59 53
40. face The purpose of the Advanced Programmer s Manual 15 to provide the assembler language programmer with the information required to make effective use of the available system routines and functions This manual applies to the 6809 version of FLEX The programmer should keep this manual close at hand while learning the system It is organized to make it convenient as a quick reference guide as well as thorough reference manual The manual is not written for the novice programmer and assumes the user to have thorough understanding of assembler language programming techniques iv FLEX Advanced Programmer s Guide Introduction The FLEX Operating System consists of three main parts the Disk Operating System DOS which processes commands the File Management System FMS which manages files on a diskette and the Utility Command Set which are the user callable commands The Utility Command Set 15 described in the FLEX User s Guide Details of the Disk Operating System and File Management System portions of FLEX are described in this manual which is intended for the programmer who wishes to write his own commands or process disk files from his own program When debugging programs which use disk files and the File Management System the user should take the following precautions 1 Write protect the system diskette by exposing or covering the write protect cutout on the diskette See the FLEX User s Guide for further details on thi
41. fication parsing command argument parsing terminal I 0 and error reporting are all handled by DOS The following sections describe the DOS global variable storage locations Memory Map the DOS user callable subroutines and give examples of some possible uses DOS MEMORY MAP The following is a description of those memory locations within the DOS portion of FLEX which contain information of interest to the programmer The user is cautioned against utilizing for his own purposes locations documented as being either reserved or system scratch as this action may cause destruction of data C080 COFF Line Buffer The line buffer is a 128 byte area into which characters typed at the keyboard are placed by the routine INBUF 11 characters entered from the keyboard are placed in this buffer with the exception of control Characters which have been deleted by entering the backspace character do not appear in the buffer nor does the backspace character itself appear The carriage return signaling the end of the keyboard input is however put in the buffer This buffer is also used to hold the STARTUP file during a coldstart boot operation 00 TTYSET Backspace Character This is the character which the routine INBUF will interpret as the Backspace character It is user definable through the TTYSET DOS Utility Default 08 a Ctrl ASCII BS 01 TTYSET Delete Character This is the character which the routine I
42. for the file being referenced Bytes 4 11 File Name This is the name of the file being referenced The name must start with a letter and contain only letters digits hyphens and or underscores If the name is less than 8 characters long the remaining bytes must be zero The name should be left adjusted in its field Bytes 12 14 Extension This is the extension of the file name for the file being referenced It must start with a letter and contain only letters digits hyphens and or underscores If the extension is less than 3 characters long the remaining bytes must be zero The extension should be left Files with null extensions should not be created Byte 15 File Attributes At present only the most significant 4 bits are defined in this byte These bits are used for the protection status bits and are assigned as follows BIT 7 Write Protect BIT 6 Delete Protect BIT 5 Read Protect BIT 4 Catalog Protect Setting these bits to 1 will activate the appropriate protection status All undefined bits of this byte should remain 0 Byte 16 Reserved for future system use Bytes 17 18 Starting disk address of the file These two bytes contain the hardware track and sector numbers respectively of the first sector of the file Bytes 19 20 Ending disk address of the file These two byes contain the hardware track and sector numbers respectively of the last sector of the file Bytes 21 22 File size This is a 16 bit num
43. ged COMMAND SYNTAX ERROR RETYPE COMMAND The command line just typed has a syntax error THAT COMMAND IS NOT ALLOWED WHILE PRINTING The command just entered is not allowed to operate while the system printer spooler is activated WRONG HARDWARE CONFIGURATION This error usually implies insufficient memory installed in the computer for a particular function or trying to use the printer spooler without the hardware timer board installed 40 FLEX Advanced Programmer s Guide DISK DRIVERS The following information is for those users who wish to write their own disk drivers to interface with some other disk configuration than 15 supplied by the vendor Technical Systems Consultants is not in a position to write disk drivers for other configurations nor do they guarantee the proper functioning of FLEX with user written drivers The disk drivers are the interface routines between FLEX and the hardware driving the floppy disks themselves The drivers released with the FLEX System are designed to interface with the Western Digital 1771 or 1791 Floppy Disk Formatter Controller chip The disk drivers are located RAM at addresses 0 00 DFAO All disk functions are vectored jumps at the beginning of this area The disk drivers need not handle retries in case of errors FLEX will call them as needed If an error is detected the routines should exit with the disk hardware status in the B register and the CPU Z Condition code bit cle
44. he interleaving of the sectors allows more time for processing the data The phenomena of missing a sector because of long processin times is called missing revolutions and results in very slow running time for programs The FLEX format reduces the number of missed revolutions thus speeding up programs 43 FLEX Advanced Programmer s Guide DESCRIPTION OF A DIRECTORY SECTOR Each sector in the directory portion of a FLEX diskette contains 10 directory entries Each entry refers to one file on the diskette In each sector the first four bytes contain the sector linkage information and the next 12 bytes not used When reading information from the directory using the FMS Get Information Record function these 16 bytes are skipped automatically as each sector is read the user need not concerned with them Each entry in the directory contains the exact same information that is stored in the FCB bytes 4 27 See the description of the File Control Block FCB for more details A directory entry which has never been used has a zero in the first byte of the file name A directory entry which has benn deleted has the leftmost bit of the name set i e the first byte of the name is negative DESCRIPTION OF A DATA SECTOR Every sector on a FLEX diskette except the two BOOT sectors has the following format Bytes 0 1 Link to the next sector Bytes 2 3 File Logical Record Number Bytes 4 255 Data If a file occupies more tha
45. hile the User Command Table is known to DOS The User Command Table may be deactivated by clearing the User Command Table Address locations FLEX Advanced Programmer s Guide DISK RESIDENT COMMANDS A disk resident command is an assembled program with transfer address which has been saved on the disk with CMD extension ASMB section of the FLEX User s Guide describes the way to assign a transfer address to a program being assembled Disk commands when loaded into memory may reside anywhere in the User RAM Area the address is determined at assembly time by using an ORG statement Most commands may be assembled to run in the Utility Command Space See Memory Map Most of the commands supplied with FLEX run in the Utility Command Space For this reason the SAVE command cannot be used to save information which is in the Utility Command Space or System FCB space as this information would be destroyed when the SAVE command is loaded The SAVE LOW command 15 to be used in this case The SAVE LOW command loads into memory at location 100 and allows the saving of programs in the C100 region The System FCB area is used to load all commands from the disk Commands written to run in the Utility Command Space must not overflow into the System FCB area Once loaded the command itself may use the System FCB area for scratch or as an FCB for its own disk I O See the example in the FMS section 17 FLEX Advanced Programm
46. if writing the sector buffer This address is relative to the beginning of the sector and is advanced automatically by the Read Write Next Byte function The user program has no need to manipulate this byte Byte 35 Random Index This byte is used in conjuction with the Get Random Byte From Sector function to read specific byte from the sector buffer without having to sequentially skip over any intervening bytes The address of the desired byte relative to the beginning of the sector is stored in Random Index by the user and the Get Random Byte From Sector function is issued to FMS The specified data byte will be returned in the A register A value less than 4 will 24 FLEX Advanced Programmer s Guide access one of the linkage bytes in the sector User data starts at an index of 4 Bytes 36 46 Name Work Buffer These bytes are used internally by FMS as temporary storage for a file name These locations are not for use by a user program Bytes 47 49 Current Directory Address If the FCB is being used to process directory information with the Get Put Information Record functions these three bytes contain the track number sector number and starting data index of the directory entry whose content is in the Directory Information portion of the FCB The values in these three bytes are updated automatically by the Get Information Record function Bytes 50 52 First Deleted Directory Pointer These bytes are used internally by
47. in these locations is the proper starting point Remember that the address is that of the FCB List Pointer locations in the FCB not the first word of the FCB A value of zero in these locations indicates that there are no open files D40B D40C Current FCB Address These locations contain the address of the last FCB processed by the File Management System The address is that of the first word of the FCB D435 Verify Flag A non zero value in this location indicates that FMS will check each sector written for errors immediately after writing it A zero value indicates that no error checking on writes is to be performed The default value is non zero 27 FLEX Advanced Programmer s Guide FMS FUNCTION CODES The FLEX File Management System is utilized by the user through function codes The proper function code number is placed by the user in the Function Code byte of the File Control Block FCB before calling FMS Byte 0 FMS should be called by a JSR to the FMS call entry On entry to FMS the X register should contain the address of the FCB On exit from FMS the CPU Z condition code bit will be clear if an error was detected while processing the function This bit may be tested by the BNE and BEQ instructions Note In the following examples the line JSR FMS is referencing the FMS Call entry at D406 Function 0 Read Write Next Byte Character If the file is open for reading the next byte is fetched from the file a
48. n The FCB must not be open for use by a file This function accesses the System Information Record for the diskette whose drive number is in the FCB There are no separate functions for reading or changing this sector All references to the data contained in the System Information Record must be made by manipulating the Sector Buffer directly This function is used internally within FLEX there should be no need for a user written program to change the System Information Record Doing so may result in the destruction of data necessitating the re initialization of the diskette There is no need to close the FCB when finished Function 17 11 hex Get Random Byte From Sector On entry the file should be open for reading or update Also the desired byte number should be stored in the Random Index byte of the FCB This byte number is relative to the beginning of the sector buffer On exit the byte whose number is stored in the Random Index is returned to the calling program in the A register The Random Index should not be less than 4 since there is no user data in the first four bytes of the sector Example To read the 54th data byte of the current sector LDX FCB Point to FCB LDA 54 4 Set to item 4 STA 35 X Put it in random index LDA 17 Setup function code STA 0 Store in FCB JSR FMS Call FMS BNE ERROR Check for errors Character is now in acc A 34 FLEX Advanced Programmer s Guide Function 18 12 hex Put R
49. n a calculation to determine the record number and offset of the appropriate error string message in the file Each error message string is 63 characters in length thus allowing 4 messages per sector If the string is found it is printed on the terminal If the string is not found due to too large of error number being encountered or if the error file itself was not located on the disk the error number is reported to the monitor terminal as part of the message DISK ERROR nnn Where nnn is the error number being reported A description of the error numbers is given elsewhere in this document CD42 GETHEX Get Hexadecimal Number This routine gets a hexadecimal number from the Line Buffer On entry the Line Buffer Pointer must point to the first character of the number On exit the carry bit is cleared if a valid number was found the B register is set non zero and the X register contains the value of the number The Line Buffer Pointer is left pointing to the character immediately following the separator character unless that character is a carriage return or End of Line If the first character examined in the Line Buffer is separator character such as comma the carry bit is still cleared but the B register is set to zero indicating that no actual number was found In this case the value returned in the X register is zero If a non hexadecimal character is found while processing the number characters in the Line Buffer ar
50. n one sector the link to the next sector portion contains the track and sector numbers respectively of the next sector in the file These bytes are zero in the last sector of a file indicating that no more data follows an end of file condition user should never manually change the linkage bytes of a sector These bytes are automatically managed by FMS In fact the user need not be concerned at all with sector linkage information 44 FLEX Advanced Programmer s Guide DESCRIPTION OF A BINARY FILE A FLEX binary file may contain anything as data all ASCII characters are allowed Each binary file is composed of one or more binary records There may be more than one binary record in a single sector A binary record looks as follows byte numbers are relative to the start of the record not the beginning of a sector Byte 0 Start of record indicator 02 the ASCII STX Byte 1 Most significant byte of the load address Byte 2 Least significant byte of the load address Byte 3 Number of data bytes in the record Byte 4 n binary data in the record The load address portion of a binary record contains the address where the data resided when it was written to the file with the FLEX SAVE command When the file is loaded for execution or use it will be put in the same memory areas from which it was SAVED A binary file may also contain an optional transfer address record This record gives the address in memory of te
51. n the Scratch Bytes area of the FCB file whose specification is the FCB is renamed to the name and extension stored the FCB Scratch Bytes area Both the new name the new extension must be specified neither the name nor the extension can be defaulted Example LDX FCB Point to FCB setup both file specs in FCB LDA 13 Setup function code STA 0 Store in FCB JSR FMS Call FMS BNE ERROR Check for errors File has been renamed Function 14 0E hex Reserved for future system use 33 FLEX Advanced Programmer s Guide Function 15 0F hex Next Sequential Sector On entry the file should be open for either reading or writing not update If the file is open for reading this function code will cause all of the remaining yet unread data bytes in the current sector to be skipped and the data pointer will be positioned at the first data byte of the next sequential sector of the file If the file is open for write this operation will cause the remainder of the current sector to be zero filled and written out to the first available data location in the next sequential sector It should be noted that all calls to this function code will be ignored unless at least one byte of data has either been written or read from the current sector Function 16 10 hex Open System Information Record On entry only the drive number need be specified in the FCB there is no file name associated with this functio
52. nd returned to the calling program in the A register If the file is open for writing the content of the A register on entry is placed in the buffer as the next byte to be written to the file The Compression Mode Flag must contain the proper value for automatic space compression to take place if desired see Description of the FCB Compression Mode Flag for details On exit this function code remains unchange in the Function Code byte of the FCB thus consecutive read writes may be performed without having to repeatedly store the function code When reading an End of File error is returned when all data in the file has been read When the current sector being read is empty the next sector in the file is prepared for processing automatically without action being required of the user Similarly when writing full sectors are automatically written to the disk without user intervention Example If reading LDX FCB Point to the FCB JSR FMS Call FMS BNE ERROR Check for errors The character read is now in A If writing LDA CHAR Get the character LDX FCB Point to the FCB JSR FMS Call FMS BNE ERROR Check for errors The character in A has been written 28 FLEX Advanced Programmer s Guide Function 1 Open for Read The file specified in the FCB is opened for read only access If the file cannot be found an error is returned The only parts of the FCB which must be preset by the programmer before issuing this
53. or several times without success before reporting the error This error may also result from illegal track and sector addresses being put in the FCB 38 10 11 12 13 14 15 16 17 18 19 20 21 FLEX Advanced Programmer s Guide DISK FILE WRITE ERROR A checksum error was detected by the hardware in attempting to write sector DOS has already tried several times without success to re write the failing sector before reporting the error This error may also result from illegal track and sector numbers being put in the FCB A write error status may also be returned if read error was detected by DOS attempting to update the diskette directory THE FILE OR DISK IS WRITE PROTECTED An attempt was made to write on a diskette which has been write protected by use of the write enable cutout in the diskette or to a file which has the write protect bit set THE FILE IS PROTECTED FILE NOT DELETED The file attempted to be deleted has its delete protect bit set and can not be deleted ILLEGAL FILE CONTROL BLOCK SPECIFIED An attempt was made to access an FCB from the open FCB chain but it was not in the chain ILLEGAL DISK ADDRESS ENCOUNTERED Reserved for future system use AN ILLEGAL DRIVE NUMBER WAS SPECIFIED Reserved for future system use DRIVES NOT READY The drive does not have a diskette in it or the door is open This message cannot be issued for mini floppys since there is no means of
54. ored in the Function Code byte of the FCB the address of the FCB is put in the X register and this entry point is called by a JSR instruction The function codes are documented elsewhere in this document On exit from this entry point the CPU Z Condition code bit is set if no error was detected in processing the function This bit may be tested with a BEQ or BNE instruction If an error was detected the CPU Z Condition code bit is cleared and the Error Status byte in the FCB contains the error number Under all circumstances the address of the FCB is still in the X register on exit from this entry point Some of the functions require additional parameters in the A and or B registers See the documentation of the Function codes for details The B X Y and U registers are always preserved with a call to FMS 26 FLEX Advanced Programmer s Guide GLOBAL VARIABLES This section describes those variables within the File Management System which may be of interest to the programmer Any other locations in the FMS area should not be used for data storage by user programs D409 D40A FCB Base Pointer These locations contain the address of the FCB List Pointer bytes of the first FCB in the chain of open files The address in these locations is managed by FMS and the programmer should not store any values in these locations A user program may however want to chain through the of the open files for some reason and the address stored
55. peration Refer to the section on Random Files for more details The file will be created on the drive specified unless the drive spec is FF which case the file will be created on the first drive found to be ready Example LDX FCB Point to the FCB Set up file spec in FCB LDA 2 Setup open for write code STA 0 Store in FCB JSR FMS Call FMS BNE ERROR Check for errors The file is now open for text write For binary write follow the example in Read open 29 FLEX Advanced Programmer s Guide Function 3 Open for Update This function opens the file for both read and write The file must not be open and must exist on the specified drive If the drive spec is FF all drives will be searched Once the file has been opened for update four operations may be performed on it 1 sequential read 2 random read 3 random write and 4 close file Note that it is not possible to do sequential writes to a file open for update This implies that it is not possible to increase the size of a file which is open for update Function 4 Close File If the file was opened for reading a close merely removes the FCB from the chain of open files If the file was opened for writing any data remaining in the buffer is first written to the disk padding with zeroes if necessary to fill out the sector Ifa file was opened for writing but never written upon the name of the file is removed from the diskette directory since the fil
56. rap is in use boot program once loaded then loads FLEX from the diskette Another sector on track 0 is the System Information Record This sector contains the track and sector addresses of the beginning and ending sectors of the chain of free sectors those available for data files The rest of track 0 is used for the directory of file names After initialization the free tracks on the diskette have format The first two bytes of each sector contain the track and sector number of the next sector in the chain The next two bytes are used to store the logical record number of the sector in the file The remaining 252 bytes are zero Initially all record number bytes are zero When data is stored in a_ file the two linkage bytes at the beginning of each sector are modified to point to the next sector in the file not the next the free chain The sectors in the diskette directory on track 0 also have linkage bytes similar to those in the in the free chain and data files A FLEX diskette is not initialized in the strict IBM standard format In the standard format the sectors on the diskette should be physically in the s order as they are logically i e sector 2 should follow sector 1 3 follow 2 etc On a FLEX diskette the sectors are interleaved so that there is t after having read one sector to process the data and request the next sector bef the sectors are physically adjacent the processing time must be very short T
57. riptions for details CCF8 CCF7 System Scratch FLEX Advanced Programmer s Guide USER CALLABLE SYSTEM ROUTINES Unless specifically documented otherwise the contents of all registers should be presumed destroyed by calls to these routines All routines unless otherwise indicated should be called with a JSR instruction In the 6809 version of FLEX the Y and U registers are preserved across all the following routines The A B and X registers should be considered changed except where noted otherwise Often a value or status is returned in one of these registers CDOO COLDS Coldstart Entry Point The BOOT program loaded from the disk jumps to this address to initialize the FLEX system Both the Disk Operating System DOS portion and the File Management System portion FMS of FLEX are initialized After initialization the FLEX title line is printed and the STARTUP file if one exists is loaded and executed This entry point is only for use by the BOOT program not by user programs Indiscriminate use of the Coldstart Entry Point by user programs could result in the destruction of the diskette Documentation of this routine is included here only for completeness CDO3 WARMS Warmstart Entry Point This is the main re entry point into DOS from user programs A JMP instruction should be used to enter the Warmstart Entry Point At this point the main loop of DOS is entered main loop of DOS checks the Last Terminator loca
58. rmal procedure for opening a file for write should be used Immediately following a successful open set the File Sector Map location of the FCB to any non zero value and proceed with the file s creation It only makes sense to create text type files in the random mode As the file is built the system creates a File Sector Map This File Sector Map FSM is a map or directory which tells the system where each record sector of the file is located on the disk The FSM is always two sectors in length and is assigned record number 0 in the file This implies that a data file requiring 5 sectors for the data will actually be 7 sectors in length The user has no need for the FSM sectors and they are automatically skipped when opening a file for read The FMS uses them for the Position and Backup function code operations The directory information of a file states whether or not a file is a random file If the File Sector Map byte is non zero the file is random otherwise it is sequential only It should be noted that random files can be Copied from one disk to another without losing its random properties but it can not be appended to another file 37 FLEX Advanced Programmer s Guide FLEX ERROR NUMBERS 1 ILLEGAL FMS FUNCTION CODE ENCOUNTERED FMS was called with a function code in the Function Code byte of the FCB that was too large or illegal 2 THE REQUESTED FILE IS IN USE An Open for Read Update or Write function was issued on an F
59. s compared to the Line Count value to determine if a full page has been printed CC1B CC1C Loader Address Offset These locations contain the 16 bit bias to be added to the load address of a routine being loaded from the disk See documentation of the System Routine LOAD for details These locations are also used as scratch by some system routines CC1D Transfer Flag After program has been loaded from the disk see LOAD documentation this location is non zero if a transfer address was found during the loading proc This location is also used as scratch by some system routines FLEX Advanced Programmer s Guide CC1E CC1F Transfer Address If the Tranfer Flag was set non zero by a load from the disk see LOAD documentation these locations contain the last transfer address encountered If the Transfer Flag was set zero by the disk load the content of these locations is indeterminate CC20 Error Type This location contains the error number returned by several of the File Management System functions See the Error Numbers section of this document for an interpretation of the error numbers CC21 Special I O Flag If this byte is non zero the PUTCHR routine will ignore the TTYSET Width feature and also ignore the Escape Character routine RSTRIO clears this byte Default 0 CC22 Output Switch If zero output performed by the PUTCHR routine is through the routine OUTCH If non zero the routine OUTCH2 15 use
60. s operation This will prevent destruction of the system disk in case the program starts running wild 2 Use an empty scratch diskette as the working diskette to which your program will write data files If something goes wrong and the diskette is destroyed no valuable data will have been lost 3 Test your program repeatedly especially with special cases of data input which may not be what the progam is expecting Well written programs abort gracefully when detecting errors not dramatically A careful programmer using the information in this manual should be able to make the fullest use of his floppy disk system FLEX Advanced Programmer s Guide DISCLAIMER This product is intended for use only as described in this document and the FLEX User s Guide Technical Systems Consultants will not be responsible for the proper functionng of features or parameters The user is urged to abide by the warnings and cautions issued in this document lest valuable data or diskettes be destroyed PATCHING FLEX It is not advisable to patch FLEX Technical Systems Consultants cannot be responsible for any destructive side effects which may result from attempts to patch FLEX FLEX Advanced Programmer s Guide THE DISK OPERATING SYSTEM The Disk Operating System DOS forms the communication link between the user via a computer terminal and the File Management System All commands are accepted through DOS Functions such as file speci
61. status If it is not an 8 control is transfered to the error handling routine described above If it is an End of File we are finished listing the file so it must now be closed The FMS Function Code for closing a file is 4 This is loaded into A and stored in the FCB Calling FMS will attempt to close the file Upon return errors are checked and if none found control is transfered back to DOS by the jump to WARMS This example illustrates many of the methods used when writing utilities Many of the DOS and FMS routines were used The basic idea of file opening and closing were demonstrated as well as file I 0 The methods of dealing with various types of errors were also presented Studying this example until it is thoroughly understood will make writing your own disk commands and disk oriented programs an easy task 48 C100 C100 C102 C103 C106 C109 C10B C10D C10F C112 C115 C117 C11A 110 C11F C121 C123 C126 C128 C12B 01 CD03 CD2D CD18 CD24 CD33 CD3F D406 D403 C840 FLEX Advanced Programmer s Guide SIMPLE TEXT FILE LIST UTILITY COPYRIGHT C 1979 BY TECHNICAL SYSTEMS CONSULTANTS INC DOS EQUATES WARMS EQU CD03 GETFIL EQU CD2D PUTCHR EQU CD18 PCRLF EQU CD24 EQU CD33 RPTERR EQU CD3F FMS EQUATES FMS EQU D406 FMSCLS EQU D403 SYSTEM EQUATES FCB EQU C840 LIST UTILITY STARTS ORG C100 LIST BRA LIST2 VN FCB 1 11572 LDX FCB JSR GETFIL BCS LI
62. the drive whose number is in the FCB for a ready status after selecting that drive and delaying long enough for the drive motor to come up to speed approx 2 seconds This is not possible in the minifloppy version due to hardware limitations In this case this routine should not delay and should simply return a drive ready status if the drive number in the FCB is 0 or 1 or a drive not ready status for any other drive number DE12 Quick Check Drive Ready This routine is the same as Drive Check Ready except the 2 second delay is not done This assumes the drive motor is already up to speed For minifloppy versions there is no difference in the two and this routine can simply be a jump to the Check Drive Ready routine NS FLEX Advanced Programmer s Guide Diskette Initialization The NEWDISK command is used to initialize a diskette for use by the FLEX Operating System The initialization process writes the necessary track and sector addresses in the sectors of a soft sectored diskette such as is used by FLEX In addition the initialization process links together all of the sectors on the diskette into a chain of available sectors The first track on the diskette track 0 15 special None of the sectors on track 0 are available for data files they are reserved for use by the FLEX system The first two sectors contain a boot program which 15 loaded by the D command of the SBUG monitor or by whatever comparable ROM based bootst
63. the file Upon return if the Z condition code is set there were no errors If there was an error the BNE LIST9 will take us to the code to report the error This section of code is the desired way to handle most FMS caused disk errors The first thing to do is call the DOS routine RPTERR which will print the disk error message on the monitor terminal Next all open disk files should be closed This can be easily accomplished by a call to the FMS close entry FMSCLS Finally return control back to DOS by jumping to the WARM START entry If the file opened successfully control will be transfered to the line with the label LIST4 At this time it is desirable to fetch characters one at a time from the file printing them on the monitor terminal as they are received Since line feeds are not stored in text files carriage returns mark the end of lines but the next line will follow immediately each carriage return received from the file is not output as is but instead a call to the DOS routine PCRLF is made to print a carriage return and a line feed As each character is received from the file by a call to FMS at label 11574 the error status is checked If an error does occur control is transferred to LIST6 Since FLEX does not store an End of File character with a file the only mechanism for determining the end of a file is by the End of File error generated by FMS At LIST6 the error status is checked to see if it is 8 end of file
64. ting of the backspace echo character Default 0 CCO8 TTYSET Eject Count The Eject Count instructs DOS as to the number of blank lines to be output after each page A page is a set of lines equal in number to the Depth Count If this byte is zero no Eject lines are output Default 0 09 TTYSET Pause Control The Pause byte instructs DOS what action to take after each page is output A zero value indicates that the pause feature is enabled a non zero value pause is disabled Default FF pause disabled CCOA TTYSET Escape Character The Escape character causes DOS to pause after an output line Default 1B ASCII ESC CCOB System Drive Number This is the number of the disk drive from which commands are loaded If this byte is FF both drives 0 and 1 will be searched Default drive 0 CCOC Working Drive Number This is the number of the default disk drive referenced for non command files If this byte is FF both drives 0 and 1 will be searched Default drive 0 CCOD System Scratch CCOE CC10 System Date Registers These three bytes are used to store the system date It is stored in binary form with the month in the first byte followed by the day then the year The year byte contains only the tens and ones digits FLEX Advanced Programmer s Guide CC11 Last Terminator This location contains the most recent non alphanumeric character encountered in processing the line buffer See comm
65. tion for TTYSET end of line character If one is found it is assumed that there is another command on the line and DOS attempts to process it If no end of line is in the Last Terminator location DOS assumes that the current command line is finished and looks for a new line to input from the keyboard If however DOS was called from a user program through the DOCMND entry point control will be returned to the user program when the end of a command line is reached 006 RENTER DOS Main Loop Re entry Point This is direct entry point into the DOS main loop None of the Warmstart initialization is performed This entry point must be entered by JMP instruction Normally this entry point is used internally by DOS and user written programs should not have need to use it For an example of use see Printer Driver section for details FLEX Advanced Programmer s Guide 009 INCH Input Character CDOC INCH2 Input Character Each of these routines inputs one character from the keyboard returning it to the calling program in the A register The address portion of these entries points to a routine in the Custom 1 0 package They may be altered by changing that package The GETCHR routine normally uses INCH but may be instructed to use INCH2 by setting the Input Switch non zero see Memory Map The users s program may change the jump vector at the INCH address to refer to some other input routine such as a routine to get a
66. tion of the FCB into the directory entry to which the FCB currently points The directory sector just updated is then re written automatically on the diskette to ensure that the directory is up to date A user program should normally never have to write into a directory Careless use of this function can lead to the destruction of data files necessitating a re initialization of the diskette Function 9 Read Single Sector This function is a low level interface directly to the disk driver which permits the reading of a single sector to which the Current Position bytes of the FCB point into the Sector Bufffer area of the FCB This function is normally used internally within FLEX and a user program should never need to use it The Read Write Next Byte function should be used instead whenever possible Extreme care should be taken when using this function since it does not conform to the usual conventions to which most of the other FLEX functions adhere Example LDX FCB Point to the FCB LDA TRACK Get track number STA 30 X Set current track LDA SECTOR Get sector number STA 31 X Set current sector LDA 9 Setup function code STA 0 Store in FCB JSR FMS Call FMS BNE ERROR Check for errors The sector is now in the FCB Function 10 0A hex Write Single Sector This function like the Read Single Sector function is a low level interface directly to the disk driver which permits the writing of single sector As such it requires
67. to point to its IRQ routine When the PRINT Queue is empty the timer is shut off and interrupts are generated The SWI3 instruction is also used quite extensively in FLEX The SWI3 vector in RAM is set by FLEX to point to its SWI3 routine Because of the SWI3 and IRQ use the MON command will not permit leaving FLEX while there is a file in the PRINT Queue All FLEX utilities the Editor the Assembler the Text Processor and BASIC are interruptable programs When writing your own programs if they are to be used while printing with the PRINT command files in the print queue they should be written to be interruptable as well At no time should the IRQ or SW13 vectors be changed in a utility which is to be run while printing In general good programming practice will yield interruptable programs SYSTEM MEMORY MAP The following memory shows the location of user RAM and several major sections of the FLEX operating system All addresses hexadecimal ADDRESS DESCRIPTION 0000 BFFF User RAM Some of the lower end of this area is used by certain utilities such as NEWDISK C000 07 Stack Area SP is initialized to 07 C080 COFF Input Buffer C100 Utility Command Area C700 C83F Scheduler amp Printer Spooler C840 C97F System FCB C980 CBFF System Files Area 00 D3FF DOS D400 DDFF FMS DEOO DFFF Disk Drivers 57
68. ty with 6800 FLEX CD39 OUTDEC Output Decimal Number On entry the X register contains the address of the most significant byte of a 16 bit 2 byte unsigned binary number The B register on entry should contain a space suppression flag The number will be printed as a decimal number with leading zeroes suppressed If the B register was non zero on entry spaces will be substituted for the leading zeroes If the B register is zero on entry printing of the number will start with the first non zero digit CD3C OUTHEX Output Hexadecimal Number On entry the X register contains the address of a single binary byte The byte to which the X register points is printed as 2 hexadecimal digits The B and X registers are preserved 18 FLEX Advanced Programmer s Guide CD3F RPTERR Report Error On entry to this routine the X register contains the address of a File Control Block in which the Error Status Byte is non zero The error code in the FCB is stored by this routine in the Error Type location A call to the routine RSTRIO is made and location Error Vector is checked If this location is zero the file ERRORS SYS is opened for random read If this location is non zero it is assumed to be an address pointing to an ASCII string containing any necessary null pad characters of a legal File name plus extension string should be 11 characters long This user provided file is then opened for random read The error number is used i
69. up One Record This is also used for random file accessing This function takes the Current Record Number in the FCB and decrements it by one A Position to the new record is performed This has the effect of back spacing one full record For example if the Current Record Number is 16 and the Backup One Record function is performed the file would be positioned to read the first byte of record 15 The file must be open for read or update before this function may be used See Random Files section for details 36 FLEX Advanced Programmer s Guide RANDOM FILES FLEX version 9 0 supports random files random access technique allows access by record number of a file and can reach any specified sector in a file no matter how large it is in a maximum of two disk reads With a small calculation using the number of data bytes in a sector 252 the user may also easily reach the Nth character of a file using the same mechanism Not all files may be accessed in a random manner It 15 necessary to create the file as a random file The default creation mode is sequential and is what all of the standard FLEX Utilities work with The only random file in a standard FLEX system is the ERRORS SYS file FLEX uses a random access technique when reporting error messages A file which has been created as a random access file may read either randomly or sequentially A sequential file may only be read sequentially To create a random file the no
70. use the file ERRORS SYS as the error file If they are non zero they are assumed to be the address of an ASCII string of characters in directory format of the name of the file to be used as the error file See the description of RPTERR for more details CC2F File Input Echo Flag If this byte is non zero default and input is being done through a file the character input will be echoed to the output channel If this byte is zero the character retrieved will not be echoed CC30 CC32 System Scratch CC33 CPU Type Flag This flag indicates the type of computer system that is running Flex If the type of computer is unknown this byte contains zero CC35 CC36 Reserved Printer Area Pointer These two bytes contain the address of the reserved printer driver area If no area has been assigned via the RM command these bytes will contain zero CC37 CC38 Printer Area Length These two bytes contain the length of the reserved printer area If no area has been assigned these bytes contain zero CC3C CCBF System Constants CCCO CCD7 Printer Initialize This area is reserved for the overlay of the system printer initialization subroutine vectors CCD8 CCE7 Printer Ready Check This area is reserved for the overlay of the system check for printer ready subroutine vector CCE4 CCF7 Printer Output This area is reserved for the overlay of the system printer output character routine vector See Printer Routine desc
71. utine CLASS automatically classifying the character On exit the character is in the A register the carry is clear if the character is alphanumeric and the B register and X register are preserved 11 FLEX Advanced Programmer s Guide CD2A RSTRIO Restore 1 0 Vector This routine forces the OUTCH jump vector to point to the same routine as does the OUTCH2 vector The Output Switch location and the Input Switch location are set to zero The INCH jump vector is reset to point to the same address as the INCH2 vector Both the File Input Address and the File Output Address are set to zero The A register and B register are preserved by this routine CD2D GETFIL Get File Specification On entry to this routine the X register must contain the address of a File Control Block FCB and the Line Buffer Pointer must be pointing to the first character of a file specification in the Line Buffer This routine will parse the file specification storing the various components in the FCB to which the X register points If a drive number was not specified in the file specification the working drive number will be used On exit the carry bit will be clear if no error was detected in processing the file specification The carry bit will be set if there was a format error int the file specifiation If no extension was specified in the file specification none is stored The calling program should set the default extension desired after GETFIL has b
72. xit the Transfer Address Flag is zero if no transfer address was found This flag is non zero if transfer address record was encountered in the binary file and the Transfer Address locations contain the last transfer address encountered The disk file is closed on exit If a disk error is encountered an error message 12 FLEX Advanced Programmer s Guide is issued and control is returned to DOS at the Warmstart Entry Point CD33 SETEXT Set Extension On entry the X register should contain the address of the FCB into which the default extension is to be stored if there is not an extension already in the FCB The A register on entry should contain a numeric code indicating what the default extension is to be The numeric codes are described below If there is already an extension in the FCB possibly stored there by a call to GETFIL this routine returns to the calling program immediately If there is no extension in the FCB the extension indicated by the numeric code in the A register is placed in the FCB File Extension area The legal codes are BIN TXT CMD BAS SYS BAK ene CO O1 0 PRT 1 Any values other than those above are ignored the routine returning without storing any extensions The X register is preserved in this routine CD36 ADDBX Add B register to X register The content of the B register is added to the content of the X register This routine is here for compatibili

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