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1. PURPOSE To establish the number of previous bytes to be shown on the screen in the SEARCH or VERIFY commands HOW TO INITIATE from a main prompt 1 Press Shift P You will see on the screen the current value of previous bytes 2 To change the value type in a new value can be 0 to 15 A double digit number is expected if you type a single digit number without a leading zero you must press lt ENTERP gt to signal to MON that you are done To leave the value unchanged press lt Esc gt SIGNIFICANCE OF PREVIOUS BYTES A value greater than 0 means that many byte values before the matching byte SEARCH or the differing byte VERIFY will be displayed on the screen MON User s Manual page 38 COMMAND Shift R Set RANGE PURPOSE To display or change the value of RANGE HOW TO INITIATE from a main prompt 1 Press Shift R HOW TO OPERATE 1 To change the value type in a new hexadecimal value can be 0000 to FFFF SIGNIFICANCE OF RANGE 1 RANGE is used to identify the end offset address of a section of memory to be acted upon in some way by a subsequent MON operation 2 Initially the value of RANGE is zero and this effectively disables the range limit in the DUMP SEARCH and UNASSEMBLE commands However making RANGE nonzero limits the memory extent of these operations to the specified address value 3 The value of RANGE is optional in the MODIFY command overwrite mode 4 A nonzero value of RANGE is
2. You can record most screen output from MON including memory dumps unassembles assembly listings and trace executions You cannot record screen output that is produced by your program when it is executing from MON s GoTo G command or Trace T command You cannot record editor screens with the Recorder but you can achieve the same effects with the edit and save capabilities built into the editor You cannot record Help screens with the Recorder but you can access the file MON HLP using the editor and then save or print it using the capababilities built into the editor When you initiate recording MON preclears the 64K segment it will use for the recorder memory with blanks 20 hex MON User s Manual page 25 COMMAND S Search PURPOSE To search memory for a specified byte character or string HOW TO INITIATE from a main prompt 1 Change the current address to the address you want to begin searching from Use the command to change the current offset OR the command to change the current segment OR the lt PgDn gt or lt PgUp gt command to change the current segment OR the N command to access the memory region you want to search 2 Determine how when you want the display to stop Use the Shift N command to set the autopause value OR the Shift R command to set the RANGE if you are not in a known region OR Be ready to press lt Esc gt or other key to interrupt the output 3 Press S
3. MON User s Manual page 17 2 The file should be organized as pages each of which begins with the Control P character and a unique two digit number or a single non digit character which will be the identifier by which the help user can access that page 3 No line should exceed 79 characters in length and each page should contain exactly 24 lines MON supplies the 25th line automatically at the bottom of each HELP page 4 The last page should have the identifier XX and need not have any additional lines MON uses this as the end of file indicator and wraps around again to the top of the file without displaying this page XX MON User s Manual page 18 COMMAND J Jump High PURPOSE This command changes MON s current address to a location higher in memory than the highest location used so far This is a usually a good step for you to take before you create a new named region e g an edit file or before you load in a new file from disk so that the new region does not collide with any existing one HOW TO INITIATE from a main prompt 1 OPTIONAL Press plus then lt Home gt This sets the current address to RELO 0000 and guarantees Effect 1 below 2 Press J EFFECTS The effect of this command depends on three values the current address CA when the command is initiated the highest used memory location HUML as defined by MON s list of known memory regions and MON s current segment adder value
4. The wildcard byte is significant only in the FILL and SEARCH commands AVAILABLE OPTIONS 1 You can enter the wildcard byte as an ASCII printable character if you prefer by pressing ALT A and then the character instead of the hexadecimal value MON User s Manual page 41 COMMAND Shift X Set Exclusion Byte PURPOSE To examine or change the value of the EXCLUSION byte HOW TO INITIATE from a main prompt 1 Press Shift X HOW TO OPERATE 1 To change the value type in a new hexadecimal value can be from 00 to FF hex Note 2 keystrokes are required 2 To disable the exclusion byte press lt Esc gt instead of typing in a value SIGNIFICANCE OF THE EXCLUSION BYTE 1 The exclusion byte is significant only in the SEARCH command AVAILABLE OPTIONS 1 You can enter the exclusion byte as an ASCII printable character if you prefer by pressing ALT A and then the character instead of the hexadecimal value OTHER COMMANDS All of the following commands must be initiated from a MON main prompt COMMAND Set Offset Address PURPOSE To change the OFFSET part of MON s current address HOW TO USE from a main prompt 1 Press the equals key 2 Type in the new hexadecimal address 4 keystrokes needed AVAILABLE OPTIONS 1 If you press lt Home gt instead of a hexadecimal number the value 0000 will be entered 2 If you press V then a digit 0 to 9 instead of a hexadecimal number the
5. page 45 lt spacebar gt Resume After Pause page 45 lt Fn gt User Defined Macro page 46 Shift lt Fn gt Define a Macro page 46 Keycodes Syntax page 47 Custom Macros Files page 48 U Format Syntax page 49 Communication with Other Programs des aaa paa satidaet dea aati a undead Sader E rite ates page 50 Appendix Assembler Syntax page A 1 MON User s Manual page 2 Preliminary Ideas 1 MON is a real mode keyboard command driven program 2 At the completion of any command MON signals that it is awaiting your next command by writing its main prompt on a new line at the left side of the screen 3 The main prompt always includes the prompt symbol or whenthe Recorder is off when the Recorder is on 4 The main prompt usually includes MON s current address the exceptions are when the message Autopause or Interrupt appears instead of the address if the command has not yet terminated Six examples of main prompts are 1E 51 0200 I O 0250 Autopause 1E710 If the current address does not appear but you want to know its value press lt Enter gt The current address will then appear in a new prompt on the next line RELO 0200 Interrupt 5 The four possible formats for MON s current address or any system address are Absolute Absolute MON Relativ
6. to complete the field Often the lt Home gt key selects a default or standard value if one exists Whenever you are not sure of what value to type in try the lt Home gt key Other ways of inputting a 16 bit value are the lt spacebar gt see 6 below Vn see Communication With Other Programs page 50 or for a segment Rn see page 42 6 The lt spacebar gt sometimes acts as an OK go ahead key a From a main prompt pressing the lt spacebar gt will resume a previously interrupted command or operation b When MON is waiting for you to input a 2 digit or 4 digit hex value it sometimes suggests an expected or last used value to you The suggested value appears at the cursor position Press the lt spacebar gt to accept the suggested value shown 7 Autopause Before beginning any MON operation that will produce a lot of screen output you can set an AUTOPAUSE parameter this is a number n from to 99 Thereafter until you change this number MON will pause after every n lines of screen output When MON pauses the message Autopause will appear in place of the current address in the main prompt To resume an autopaused operation simply press the lt spacebar gt To disable AUTOPAUSE set the AUTOPAUSE parameter to zero There are two ways to set the AUTOPAUSE parameter from a main prompt MON User s Manual page 4 The Quick Way The Regular Way Press a digit key 0 to 9 Press Shift N and then a 2 digit deci
7. 1 Make sure that the psuedo op LIST appears in the source file or in the assembler MACRO 2 Start the RECORDER by pressing R then 1 3 Press A lt Homes to initiate the assembly process 4 When assembly is finished stop the RECORDER and edit the assembly list press R then 5 save it to disk press R then 4 or print it press R then 4 then PRN as the filename See Appendix A for required Assembler Syntax COMMAND A Assemble Patch Assemble PURPOSE To assemble one or more assembly language source statments typed at the keyboard into machine language object code This is useful for patching an existing machine language program HOW TO INITIATE from a main prompt 1 Change the current address to the address you want to put the object code Use the command to change the current offset OR the command to change the current segment OR the lt PgDn gt or lt PgUp gt command to change the current segment OR the N command to access the memory region you want to assemble into 2 Press A You see the assembler prompt gt on the screen 3 Type in an assembly language statement for example lt space gt MOV AL 6 lt ENTER gt 4 Additional assembly language statements if desired can be typed in remember to leave a leading space or TAB before the mnemonic and end each line by pressing the lt ENTER gt key HOW TO INTERPRET RESULTS 1 After each lt ENTERP gt you will see the object byte s for the i
8. 75 hex ASCII u is stored at memory location RELO 0402 0420 and 042E 65 hex ASCII e is stored at RELO 0408 040F 0411 0415 0427 Note that nonprintable characters e g the OD and OA bytes at addresses 041D and 041E are shown as dots in the ASCII field AVAILABLE OPTIONS 1 If you want to display only a few bytes use the Single Line Dump command lt CrsrDn gt instead of the D command This always results in a single dump line of 16 bytes If the current address does not end with 0 the address sequence of the bytes will not begin with zero but 4 byte clusters will still begin at 0 4 8 or C 2 After the dumping stops due to autopause end of range or keyboard interrupt you can resume it by pressing the lt spacebar gt once 3 The Shift D Command allows you to see and change the following parameters which affect the screen output from the dump command LineLength Printable Range No Reqd Compact Runs 4 See the U unassemble command if you want a dump function with greatly increased customization cabability COMMAND E Edit PURPOSE To edit create or modify an ASCII file in memory HOW TO INITIATE from a main prompt 1 Change the current address to any address within the file to be edited a For a new file to be created Change the current address to the memory location where you want the file to begin Suggested location REL1 0000 or use the J command b For a file already in memory U
9. Name AX AL SI DH iii Absolute memory offset 5 17H 1234H PSM must be in square brackets iv Register indirect memory offset SI BX PSM Register name must be in square brackets v Symbolic Address or Value SUM SHOW SM The symbolic name must be defined elsewhere in the program as a label or in a OFFSET TOTAL DW DB or EQU statement The keyword OFFSET if present means the address of instead of the contents of vi A literal ASCII constant A today is Use single quotes to bracket ASCII constant Note P The letter B for byte or W for word may precede these forms in fact it may be required if the operand size 8 or 16 bits would otherwise be ambiguous Thus MOV AL SI is OK but INC SJ is illegal because it is ambiguous You must use INC B SI or INC W SI This use of B or W is a shorthand for the longer BYTE PTR or WORD PTR required by other assemblers Note M Mixed memory expressions of the form VARIABLE xx yy tcc are allowed where VARIABLE is a symbolic name xx is either SI or DI yy is either BX or BP and cc is a constant max 16 bits Note S A segment override prefix CS DS ES or SS can prefix the mnemonic or memory operand in most instructions Thus ES MOV AL SI and MOV AL ES SI have the same meaning COMMENTS if present follow a semicolon which follows the last operand on the line Every line must be terminated in a source file by a carriage r
10. SA When you execute the J command MON examines its list of known memory regions to determine HUML Then 1 If CA lt HUML then the current address is changed to HUML 10HxSA rounded down if necessary to a whole multiple of SA 2 If CA gt HUML then the current address is changed to CA 10HxSA rounded down if necessary to a whole multiple of SA 3 If the result of the above operation 1 or 2 is less than REL1 0000 MON increases the current address to REL1 0000 The net effect is that the current address becomes at least REL1 0000 and least 8xSA bytes higher than the highest byte in any of the known memory regions If you press J more than once the current address is placed even higher in memory This is useful if you anticipate that the highest existing memory region will grow EXAMPLE assuming the current address is RELO A396 when J is pressed four times RELO A396 Setting Segment above highest named region 2994 0000 Adding 0400 to Current Segment 2D94 0000 Adding 0400 to Current Segment 3194 0000 Adding 0400 to Current Segment REL2 0000 AVAILABLE OPTIONS 1 The Shift J command allows you to change the current segment adder value SA MON User s Manual page 19 COMMAND L Load PURPOSE To read a file from disk into memory HOW TO INITIATE from a main prompt 1 Change the current address to the location you want the file to begin at Use the command to change the current offs
11. address 4 keystrokes required of the beginning address of the program 4 MON remembers these typed in values and the next time you want to execute this program you can type G then lt spacebar gt then lt spacebar gt to repeat the address given in step 3 HOW TO INTERPRET RESULTS 1 If your program returns normally a message Normal Return appears on the screen along with a report of the final register values 2 If your program produces any output to the screen it will appear on the screen line below the GOTO prompt 3 If your program contains one or more INT 3 instructions also called software interrupts then MON will report each time an INT 3 is encountered in the execution and will show a register dump 4 Execution can be paused after n INT 3 executions by means of MON s autopause or by a keyboard interrupt press any character key Pressing the lt spacebar gt will then resume the execution of your program from the INT 3 location 5 If your program hangs up in an infinite loop you can interrupt it and allow MON to regain control by pressing lt Esc gt MON will show a register dump and give you a main prompt You can then resume execution if you wish by pressing the lt spacebar gt AVAILABLE OPTIONS 1 After executing part of your program and interrupting it with an INT 3 instruction or by an lt Esc gt keypress you can switch over to tracing the rest of the program by pressing T then lt EN
12. gt It is part of the Custom Macros file F2 optional comments Note that the function key name here F2 must appear lt Home gt 0100 he lefi in MON i h f this line L PGM COM lt Enter gt at the left margin ignores the rest of this line you can use it for a title or for comments The body of the definition begins on the next line and continues until the next line in the file that is not indented In other words body lines must be indented This file section specifies the two keystrokes plus and lt Home gt followed by the 5 keystrokes 0100 followed by the 8 keystrokes LPGM COM followed by lt Enter gt Spaces endlines blank lines and tabs in an lt Fn gt definiton are ignored so that you can format the file into lines and groups of keystrokes that make sense to you Besides the printable letter number and puncuation characters you can specify certain other keys in an lt Fn gt definition by using the angle bracket notations shown here lt TAB gt lt ESC gt lt ENTER gt lt BKSP gt lt INS gt lt HOME gt lt DEL gt lt END gt lt PGUP gt lt PGDN gt lt SPACE gt Key combinations using the Shift or Control keys can be specified e g lt SHIFT gt A lt CONTROL gt D specify Shift A and Control D respectively Alt key combinations are limited to lt ALTA gt and lt ALTHsS signifying Alt A and Alt H respectively lt Fn gt definitions are not case sensitive you can
13. in Assembler with the END Not usually MON uses only the MACRO column one directives directive first one Function Key with Fn in column Indented before the next Yes each with a different value Definition one n 0to9 Keycodes NBC1 line of n Unassemble with Ux in column Indented Before the next Yes each with a different ID Format one x any U Format NBC1 line orat character x Definition printable character Codes the character Tf the file contains more than one ASM section or more than one definition for the same function key or more than one definition for the same Ux i e having the same ID character x MON uses the first one in the file Keycodes Syntax is described under the Shift lt Fn gt command U Format Codes are described immediately following MON User s Manual page 49 U FORMAT CODES U Format Codes are the building blocks of U Format definitions The code forms and their meanings are Code _ Significance or Effect when using the U command B output a hex byte followed by a space W output a hex word followed by a space D output a hex doubleword followed by a space Tnn TAB to screen column nn nn 1 to 79 Ann output exactly nn nn 1 to 60 ASCII characters then a space A output ASCII characters max 60 up to the first non printable character begin a new line in the screen output text copy the TEXT onto the screen output begin a new screen line and return t
14. list will be produced starting from the program address of label and going thereafter for nlines program lines For example LIST LOOP 10 will cause a 10 line listing beginning with the line having the label LOOP MON User s Manual page 8 SOURCE segment offset or SOURCE RegionName SOURCE MODE ONLY Examples SOURCE 1 0 SOURCE 1 0800H SOURCE TEST SRC This psuedo op directs the assembler to look for a source file at the indicated location in memory In the first form if no segment is specified then RELO is assumed In the second form RegionName must be in MON s list of known regions More than one SOURCE psuedo op can be included in the defaults file AMACRO Like INCLUDE statements in other languages SOURCE statements allow multiple source files to be effectively chained together to form larger files Source psuedo ops can be nested one source file can contain another SOURCE statement to a maximum of 4 levels deep In this way you can invoke a Library source file in your program ALIGN value This psuedo op causes MON s current address where the following program instruction will be assembled to to increase if necessary to make the address an integral multiple of value For example if a developing program occupies memory locations RELO 0100 to RELO 0173 so far and the assembler then encounters the instruction ALIGN 100H then the assembler will assemble the next instruction into locat
15. lt Esc gt press D This brings you back into the editor Now move the cursor to the end of the block you want to delete and press D again The block will be deleted from the file However it is copied into a paste buffer so that it can be put somewhere else in your file see the PASTE command below b COPY BLOCK After lt Esc gt press C This brings you back into the editor Now move the cursor to the end of the block you want to copy and press C again The block will remain unchanged in the file you are editing but a copy will be put in the paste buffer c PASTE FROM BUFFER After lt Esc gt press P This copies the contents of the paste buffer into your file at the current cursor position and returns you to the editor and your modified file NOTE The paste buffer can hold only one block at a time Each new DELETE or COPY block operation erases the previous contents of the paste buffer PASTE operations leave the paste buffer contents unchanged d WRITE to disk or printer After lt Esc gt press W This brings you back into the editor Now move the cursor to the end of the block you want to write and press W again The selected block is highlighted and you are prompted for a destination Type the pathname and press lt Enter gt The highlighted block is written to disk or to the printer if the name PRN is used OPTIONS i If you do not move the cursor between the first and second W then the entire file is written ii I
16. required in the MODIFY insert mode EDIT and WRITE commands IMPLICIT SETTINGS OF RANGE 1 RANGE is automatically set after a file is loaded from disk L command 2 RANGE is automatically set by the N command when a new memory region is accessed MON User s Manual page 39 COMMAND Shift T Set Trace Mode PURPOSE To examine or change the value of the trace mode for use with the TRACE T command HOW TO INITIATE from a main prompt 1 Press Shift T You see RELO 0000 Trace Outputs Registers NO Instructions NO Bottom Window NO with the blinking cursor at the first NO HOW TO OPERATE 1 You can type Y yes or N to each of the three items displayed and the cursor moves to the next one After the third item you are returned to a main prompt 2 Alternatively you can choose any combination of the three Yes No options by selecting a numeric value called the trace mode Each of the three Yes No items corresponds to one bit in trace mode To change the value of trace mode type in a new number 0 to 7 SIGNIFICANCE OF TRACE MODE 1 The trace mode determines how much detail you see on the screen when you trace execute a program 0 gives no trace output 7 gives maximum trace output Trace Mode value 0 1 2 3 4 5 6 7 Use Bottom Window No Yes No Yes No Yes No Yes Unassemble Instructions No No Yes Yes No No Yes Yes Show Register Values No No No No Yes Yes Yes Yes SIDE EFFECTS 1 Choosin
17. segment address by 1000 hex i e to increase the current MON relative segment by 1 HOW TO INITIATE from a main prompt 1 Press the lt PgDn gt key OTHER EFFECTS COMMAND lt spacebar gt Resume After Pause PURPOSE To resume a paused ASSEMBLE DUMP GOTO SEARCH TRACE UNASSEMBLE VERIFY or lt CrsrLft gt repetitive one line dump command HOW TO INITIATE from a main prompt 1 Press the lt spacebar gt COMMENT 1 Each of the commands named above in PURPOSE causes the lt spacebar gt to be armed to resume the command after a keyboard interrupt or autopause 2 If pressing the lt spacebar gt has no effect then the previous command has run to completion and cannot be resumed MON User s Manual page 46 COMMAND lt Fn gt User Defined Macro function key F1 to F9 PURPOSE To execute a user defined macro sequence of commands HOW TO INITIATE from a main prompt 1 Press the lt Fn gt key n 1 to 9 COMMENTS 1 The meaning of the function key lt Fn gt must be defined in a section of the Custom Macros file The section begins with the two characters Fn where n is a digit 1 to 9 See the Shift Fn command below for syntax details of this definition 2 Execution of a lengthy function key macro can be interrupted by pressing the lt Esc gt key the lt spacebar gt or any letter key Once it is interrupted however the function key macro cannot be resumed it must be restarted fr
18. than 16 bytes This happens if you begin dumping from a current address which does not end with 0 4 byte clusters will still begin at 0 4 8 and C 4 The ASCII field shows the ASCII characters corresponding to the 16 bytes on the display line If a byte is not a standard printing character i e if its value is outside the range 20 hex to 7E hex then a dot is shown 5 Constant Fields If one or more consecutive display lines will all show the same content value they will be shown on the screen as a single line as 1805 0000 to016F Constant Field of All 00 s EXAMPLE OUTPUT The following 5 lines show a sample dump output The current address was set to RELO 0400 initially AUTOPAUSE was set to 3 and the default dump options were used RELO 0400 DUMP RELO 0400 46 6F 75 72 73 63 6F 72 65 20 61 6E 64 20 73 65 Fourscore and se RELO 0410 76 65 6E 20 79 65 61 72 73 20 61 67 6F OD OA 6F ven years ago o RELO 0420 75 72 20 66 61 74 68 65 72 73 20 62 72 6F 75 67 ur fathers broug Autopause Hexadecimal byte field ASCII field 16 bytes per line 16 characters line Address 0 I a 3 4 5 6 7 8 9 A B C D E F From the above sample output we can glean information such as MON User s Manual page 11 46 hex ASCII F is stored at memory location RELO0 0400 6F hex ASCII o is stored at memory location RELO 0401 0406 041C 041F and 042D
19. 0100 RELO FFOO Only one SYMBOLS directive should appear in any set of files to be assembled together ORG segment offset Examples ORG ORG 0 0100H ORG 1100H ORG 2 0 This psuedo op sets MON s current address so that subsequent assembly language instructions will be assembled into memory beginning at the specified location If no address is specified RELO 0100 is assumed If no segment is specified RELO is assumed Multiple ORG directives can appear in a file ERROR option SOURCE MODE ONLY where option is one of the words EDIT HALT or RUN This psuedo op determines what action the assembler will take in the event it detects an error in your source file EDIT means it will automatically switch you to the editor so that you can correct the error immediately HALT means the assembler will pause you can press the spacebar if you want to continue assembly in spite of the error RUN means to continue assembling without pause after an error A source file can have more than one ERROR statement Each ERROR statement prevails until the next ERROR statement is encountered LIST label nlines or NOLIST SOURCE MODE ONLY This psuedo op determines whether the assembler will write an assembly list to the screen during the second pass of assembly If MON s RECORDER is running during assembly the assembly list can be saved to disk or printed If you include label and nlines then a partial assembly
20. 147 0148 014B 014C 014F 0150 0153 0154 0157 vo vil v2 V3 v4 V5 V6 V7 V8 v9 The purpose of this area is to allow MON to interact with other programs that may execute while MON is still loaded in memory For example user programs that are assembled by MON and then executed with the G GoTo command or the T Trace command can deposit values into any or all of these locations and MON can then use them as address values in its commands To implement this design goal a special variable input capability has been added to MON A special MON command has also been added to permit communication in the reverse direction i e from MON to the other program Variable Input Capability Whenever MON is awaiting your input of a hexadecimal word value 4 hex digits you can type instead one of the variable names VO V1 V9 MON will retrieve the value from its memory space and use it as if you had entered 4 digits manually This allows you to set among other things the following quantities from values deposited by another program MON s Current Address Beginning or End addresses of a named region GoTo Address Address range specification in Copy or Verify commands Set range J L and breakpoints parameters Set screen attributes Variable Output Capability The main prompt dot command page 42 allows MON to write to the variables VO V9 With it the offset part of MON s current addres
21. 4 Type in the byte or byte string you want to search for Each byte must be in hexadecimal and therefore requires two keystrokes 5 When you have finished entering your search byte or string maximum 32 bytes long press lt ENTER gt HOW TO INTERPRET RESULTS 1 Each instance of a match found results in an output of a 16 byte dump line with the address es of the found occurrence s shown at the left side of the screen 2 At the end of the search MON reports the number of finds AVAILABLE OPTIONS 1 After screen output stops due to autopause end of range or keyboard interrupt you can resume it by pressing the lt spacebar gt once 2 If you prefer to specify one or more bytes of the search string in terms of their printable ASCII representations instead of in hexadecimal notation you can switch to ASCII input mode by pressing ALT A After entering zero or more ASCII characters you can switch back again to hex mode if desired by pressing ALT H 3 If you want to see some of the bytes PRECEEDING each match you can use the Shift P command to specify the number of previous bytes 1 15 you want displayed with each match 4 You can make one or more of the search string bytes a wildcard by means of the Shift W command A wildcard byte in the string is considered to match ANY byte value in memory 5 You can make one or more of the search string bytes an exclusion byte by means of the Shift X command An excl
22. IFY commands HOW TO INITIATE from a main prompt 1 Press Shift l HOW TO INTERPRET RESULTS 1 When the segment part of the current address in MON s main prompt is I O you are accessing I O ports instead of memory addresses HOW TO TERMINATE I O ACCESS 1 Press Shift l again In other words The Shift command toggles the segment part of the current address between memory and I O spaces COMMAND Shift J Change the Segment Adder PURPOSE The Shift J command allows you to change the parameter which MON uses in executing the J command HOW TO EXECUTE 1 Press Shift J 2 Type in the new 4 hex digit value you want for the Segment Adder SIGNIFICANCE OF THE SEGMENT ADDER The segment adder is used by MON is calculating a new currrent address when the J command is used See the J command for details MON User s Manual page 35 COMMAND Shift K Clear the Screen PURPOSE To clear the screen or set screen colors HOW TO INITIATE from a main prompt 1 Press Shift K The screen is cleared and a new main prompt appears at the upper left corner 2 If you press Shift K a second time you will see on the screen 128 numbered attribute settings and a report of the current screen attribute settings for normal and inverse screens You can type in new hex values if you wish to change screen colors Inverse screen colors are used for the top and bottom screen windows when tracing a program and for highlighting in th
23. MON User s Manual page 1 MON User s Manual for MON Version 2 0 September 1995 1995 by Robert J Borrmann Preliminary Ideas The main prompt The current address Memory address display modes page 2 Some Conventions in MON Numerical values Cursor shape Entering values The lt Esc gt lt Home gt and lt spacebar gt keys Autopause Keyboard interrupt 000 page 3 MON s Memory Map 64 page 4 Letter Commands Aedes naan Assemble Source File page 5 Avie veer vbRe Assemble Patch Assemble page 6 ERTA Assembler Directives Pseudo Ops ee e ORG ERROR LIST page 7 eee eee SOURCE ALIGN page 8 CEE COPY ei ee AER See page 9 D rink Dump or Display page 10 Beacons Edit sc ges eeeaseie reds etana page 11 Becca Fill erena a EE page 14 Giry Ters GoTo ere re saree SE EAN page 15 m GRR eee Help irie nae AEREE page 16 Lil Jump High page 18 PERERA Load or aE E page 19 M esie Modify oaeaeei neatins page 20 Neva nee nesas Named Regions page 21 R arcieri Recorder e ee ee ee page 23 So descents Searches weer iciee ed teas page 25 T aieesees Trace Asya reyes hae gue ee Re Sete be page 26 U teaiseewhas Unassemble page 27 V widisawaes Verify 2 veer R ETE ii dels page 28 We eee te Write Sores Seach ge page 29 Shifted Letter Commands Shift A Set Assembler O
24. Manual Appendix page A 54
25. NAL Press N again This results in a list on the screen of all memory regions currently known to MON 3 Press any region s Access Key This changes MON s current address to the access address shown for that region and returns you to MON s main prompt SIDE EFFECTS 1 Each time a new memory region is accessed MON changes its current address to the last accessed address in that region This makes it possible for example to return to the same point in a text file when re entering the editor 2 Each time a new memory region is accessed MON changes the value of RANGE to the region s end address CHANGING REGION PARAMETERS MANUALLY If after pressing N is step 1 above MON is currently accessing a named region then you can press one of the five keys lt Home gt lt End gt lt Ins gt lt Del gt This allows you to change the region s access key beginning address end address name or to delete the region respectively HOW ARE NAMED REGIONS CREATED MON automatically creates new named regions during disk I O and as a result of executing the M modify command the E editor command and the A assemble source file command You can manually create a new named region by pressing lt Ins gt when at a main prompt Type in a name then press lt ENTER gt This creates a new region with address range beginning and ending at the current address You can then widen the address limits if you wish as described in the previo
26. NGE INL NLE INP JPO JNS NZ NO which are the conditional jump mnemonics without the leading J The instruction is any legal instruction The assembler converts this source line into two instructions the first a conditional jump around the second such that instruction is executed if and only if condition is true Thus during Example these source lines are assembled as if they were execution of the example shown BL ae BL ee sel will be incremented if and only if AL INC BL equals 5 NEXT LEGAL PROCESSOR MNEMONICS AAA AAD AAM AAS ADC ADD AND CALL CBW CLC CLD CLI CMC CMP CMPSB CMPSW CWD HLT IDIV IMUL IN INC INT INTO IRET JA JAE JB JCXZ JBE JC JE JG JGE JL JLE JMP JNA JNAE JNB JNBE JNC JNE JNG JNGE JNL JNLE JNO JNP JNS JNZ JO JP JPE JPO JS JZ LAHF LDS LEA LES LODSB LODSW_ LOOP LOOPE LOOPZ LOOPNE LOOPNZ MOV MOVSB MOVSW MUL NEG NOP NOT OR OUT PUSH POP POPF PUSHF RCL RCR RET RETF ROL ROR SAHF SAL SAR SBB SCASB SCASW_ SHL SHR STC STD STI STOSB STOSW_ SUB TEST WAIT XCHG XLAT XOR Legal prefixes are LOCK REP REPE REPNE REPNZ_ REPZ CS DS ES SS SAMPLE SYNTAX FILE See the sample syntax file SYNTAX SRC for examples of allowable assembler syntax Although this program does nothing useful you can assemble it and execute it if you wish MON User s
27. PURPOSE To change the memory address display mode used in MON s main prompt HOW TO INITIATE from a main prompt 1 Press Shift M one or more times Each time Shift M is pressed another mode is selected of the three available modes Segmented Absolute and MON Relative MEMORY DISPLAY MODES 1 In the segmented mode the address is of the form XXXX YYYY where XXXX denotes the current segment and YYYY denotes the current offset 2 In the absolute mode the address is of the form ZZZZZ In the 8086 family of microprocessors the absolute address ZZZZZ is determined from the segment XXXX and offset YYYY by the equation ZZZZZ XXXX0 OYYYY Example Segment 1234 hex and offset 5678 hex denotes absolute address 12340 5678 179B8 hex 3 In the MON Relative mode the address is of the form RELn YYYY where n denotes the current MON relative segment 0 to 9 MEMORY in MON 1 The available user memory in MON means that memory which you can use for editing assembling echoing or other operations which require storage The lowest address of this user memory area is displayed when you first invoke MON and is called MON s home address In segmented form it is XXXX 0000 where XXXX is MON s home segment In MON relative form it is RELO 0000 2 Example See MON s Memory Map on page 4 If 1EA5 is MON s home segment then the home address is 1EA5 0000 or 1EA50 or 0 0000 all equivalent Every segment is 64 Kbytes long The maxi
28. Press Shift B 2 If you do not wish to change any breakpoint values press lt ENTER gt FOR EACH OF THE FOUR BREAKPOINTS 1 If you want to set a new breakpoint or change an existing one you can overtype the old with a new hexadecimal value 4 keystrokes needed 2 If you want to zero a breakpoint this turns it off press lt Home gt 3 If you want to specify a breakpoint symbolically press the quote key and then type in a line label maximum 10 characters and then press lt ENTER gt The numerical equivalent of the label and the symbolic name will be shown on the screen NOTE Symbolic specification of breakpoints is possible only if the symbol table is resident in memory e g if you have used MON s assembler in this working session with MON to assemble the program MON User s Manual page 32 COMMAND Shift D Set Dump Options PURPOSE To set certain options to be used when dumping memory D command HOW TO INITIATE from a main prompt 1 Press Shift D Then you see on the screen DUMP OPTIONS LineLength Printable No Reqd CompactRuns 16 20 7F Hex 00 Y The cursor initially is under the 16 To accept a value shown press the lt spacebars gt to change a value type in the new value The cursor then advances to the next field After all values have been accepted and or changed you are returned to a main prompt To return prematurely press lt Esc gt SIGNIFICANCE OF THE PARAMETERS These par
29. TER gt THE FINE PRINT 1 The Goto command turns over control of the computer to your program except that MON watches for an lt Esc gt keypress keyboard interrupt If your program is ill behaved e g disabling interrupts writing to memory being used by another program etc MON may never be able to regain control 2 The Goto command sets the CS and IP registers to the goto address values you type in and sets the other segment registers DS ES SS to the same value as CS It also sets SP 0000 and then puts a return address and an INT 3 instruction on the stack to return control to MON when a RET is executed MON User s Manual page 16 COMMAND H Help PURPOSE To summarize some important operating instructions for MON HOW TO INITIATE from a main prompt 1 Press H A menu of available help topics appears 2 Press a letter key or a 2 digit number code identifying the topic you want help on Information on that topic instantly appears on the screen 3 Many help screens have cross references to other help screens Repeat step 2 as often as you like 4 Screen H reproduced below summarizes other keys you can use 5 Exit from HELP by pressing the lt Esc gt key H How To Use HELP ON s Help System consists of a number of screens of information Each screen has an identifying letter or 2 digit number at the top left preceded by the symbol For example the screen you are looking at now is
30. To save the current offset address into a location accessible to other programs HOW TO USE Set the current offset to the value you want to save Press the dot period and then press V then n where n is a digit 0 to 9 This saves the offset value into the indicated save variable see page 50 MON User s Manual page 43 COMMAND lt Home gt Move to Beginning PURPOSE To change the current address to the beginning of the currently accessed known region HOW TO EXECUTE from a main prompt 1 Press the lt Home gt key COMMAND lt Ins gt Define New Region PURPOSE To define a new known region to MON HOW TO EXECUTE from a main prompt 1 If the recorder memory see R command is not empty purge it by pressing R 3 R 4 or R5 2 Change the current address to the address you want the region to begin at Use the command to change the current offset OR the command to change the current segment OR the lt PgDn gt or lt PgUp gt command to change the current segment 3 Press the lt Ins gt key 4 Type in the RegionName you want to give to this new region 30 characters max Suggestion You can name it with the pathname it will finally occupy later when you save it to disk 5 Press the lt ENTER gt key EFFECTS OF THIS COMMAND 1 A new region is added to MON s list of known regions The maximum capacity of the list is 15 regions If you try to add a 16th region the last one will be deleted an
31. ameters affect principally the dump D command but Printable also affects what is regarded as a printable byte value in the formatted unassemble command and in the editor LineLength Initially 16 can range from 01 to 20 If LineLength is greater than 16 the ASCII field presentation at the right side of the screen will not be shown If LineLength is a multiple of 4 then an extra space is inserted before any byte that has an address that is a multiple of 4 making 4 byte clusters on the screen Printable Initially 20 7E these two values define for MON what you consider to be the range of printable byte values If you make the range include ODH and OAH then screen printouts of those values may become irregular because these codes are used by MON to denote a carriage return and linefeed CRLF No Reqd Initially 00 this denotes the number of printable bytes on a dump line that there must be in order for MON to show the dump line on the screen Maximum value 20 which will result in no dump lines only runs see below being reported CompactRuns Initially Y meaning Yes This means that if one or more dump lines would consist of the same repeated byte value then a single line report of this fact will be made instead of the multiple repeated dump lines Can be Y Yes or N No MON User s Manual page 33 COMMAND Shift G Set GOTO Parameters PURPOSE This command allows you to set up some command line parameters bef
32. are see also 3 below a In the editor bytes are entered and displayed as characters b In the assembler numbers you enter are decimal by default c In disk I O and region names you enter names as characters 2 Cursor Shape The shape of the blinking cursor denotes the expected input form Single Underline Cursor Hexadecimal input is expected Large Block Cursor Character input is expected insert mode Small Overblock Cursor Character input is expected overstrike mode In the editor pressing the lt Ins gt keys toggles between the last two modes 3 Hex or Character Input You can usually enter byte values in either form Press Alt A to get the Large Block Cursor Press Alt H to get the Single Underline and then enter bytes as characters e g Cursor and then enter bytes as hex values press A to enter 41 hex e g press 4 then to enter 41 hex 4 The lt Esc gt key in general allows you to abort any command in progress or to back out of any command that you got into by mistake Pressing lt Esc gt once or twice should always get you back to MON s main prompt 5 Entering 16 Bit Values When MON expects you to enter a 4 digit hexadecimal address it shows its single underline cursor at the beginning of a field of 4 dots Simply key in the 4 digits e g O2AC do not press lt Enter gt However if you omit the initial zero and type 2AC then you must press lt Enter gt
33. at is MON s Recorder It is a facility which lets you make a log in memory of most main screen output from MON It is really useful because it provides you with an audit trail of what you did and saw with MON When MON assembles a file the record file constitutes an ASSEMBLY LIST When MON dumps memory the record file is the memory dump When MON traces execution of a program you are trying to debug the record file captures every action of the program so that you can study its history in detail to find the bug or document its operation in a report To use the recorder you must first turn it on then perform some action in MON that results in screen output you want to record and finally write the log file to disk or edit it action 4 or 5 which also turn the recorder off HOW TO INITIATE from a main prompt 1 Press R then a number 1 to 5 depending on which action you want to take EXPLANATION OF THE SCREEN DISPLAY RI BLOe0L00 RECORDER as OFF Memory in USGS se cece cae eid var dhe eile wes wo wane we detente fee Sorter es 1 On 2 Off 3 Clear 4 Disk Print 5 Edit PRESS 1 2 3 4 5 or Esc The recorder memory is 64K bytes long Each dot in the Memory in Use display represents 2K of unused memory Each X represents a fully or partially used 2K block You should not let the recorder memory overflow Execute the R 1 command periodically as you are recording to see the progress
34. d the new one will take its place in the list 2 The beginning and end addresses of the new region will be set to the value of the current address You can change these as described under the N command 3 The modification count of the region will be set to zero COMMAND lt End gt Move To End PURPOSE To change the current address to the end address of the currently accessed memory region HOW TO INITIATE from a main prompt 1 Press the lt End gt key MON User s Manual page 44 COMMAND lt CrsrDn gt One Line Dump PURPOSE To display a single line of memory bytes or input port bytes HOW TO INITIATE from a main prompt 1 Change the current address to the memory location whose contents you want to display Use the command to change the current offset OR the command to change the current segment OR the lt PgDn gt or lt PgUp gt command to change the current segment OR the Shift l command to access input ports instead of memory locations OR the N command to access the memory region you want to display 2 Press the lt CrsrDn gt cursor down key COMMENTS 1 This is a quick DUMP D command which always results in only a single line of output on the screen 16 bytes 4 byte clusters of bytes begin with addresses ending with 0 4 8 and C 2 The current offset address is incremented by 0010 hex COMMAND lt CrsrUp gt Decrease Offset PURPOSE To decrease the current offset addres
35. e Address in the I O Segmented Non Segmented Segmented Space Input amp Memory Address Memory Address Memory Address Output Ports Example 1E51 0200 1E710 RELO 0200 T O 0250 Segment 1E51 Segment RELO Port Number Offset 0200 Offset 0200 0250 6 You can switch among the three memory address display modes with the Shift M command You can switch between memory and I O spaces with the Shift I or the plus command 7 The principal ways of changing the value of the current address are the following commands Command Command Change Offset Change Segment N Change to a Known Region J Change to a Higher Location lt Home gt _ Change Offset to Beginning lt End gt _ Change Offset to End lt PgUp gt Change Segment lt PgDn gt Change Segment lt Decrease Offset by 1 gt Increase Offset by 1 T Decrease Offset by 10H 4 Increase Offset by 10H MON s Current Address is important because many commands depend on the current address to determine what memory area they will work on or work from This is especially true for the edit command E and the various memory display commands D and U Therefore you may have to change the current address before you initiate the command you want MON User s Manual page 3 Some Conventions in MON 1 Numerical Values Generally you should enter numerical values and MON will display them in hexadecimal The exceptions
36. e editor NOTE The initial Shift K clears only the main screen window it does not affect the top or bottom windows used in the trace function To undo the 3 window split screen press Shift T then lt Esc gt COMMAND Shift L Set Load Parameter PURPOSE To set the value of the Load Parameter used in MON s Load L command HOW TO EXECUTE 1 Press Shift L 2 Type in the new 4 hex digit value you want for the Load Parameter SIGNIFICANCE OF THE LOAD PARAMETER This parameter controls the maximum size of the parts a large file is broken into when it is loaded from disk into memory Its default value is 0000 hex which means 64K bytes With this value any file less than 64K bytes in length will be loaded as is into memory Any file longer than 64K bytes will be broken into 64k byte parts and loaded into memory part by part The names of these memory regions will include the designations Part 1 Part 2 etc However these regions cannot be added to by editor operations because the editor buffer is limited to 64K bytes The solution to this is to set the Load Parameter to say E000 hex before loading the file into memory Then the large file will be loaded in 56K byte E000 hex chunks each of which can be edited as usual a maximum of 2000 10000 E000 hex additional bytes can be added to it In this way large text files can be handled by MON s editor MON User s Manual page 36 COMMAND Shift M Set Memory Display Mode
37. e in the hexadecimal segment address of the beginning of the second memory block 4 keystrokes needed Alternatives V S or R 5 Type in the hexadecimal offset address of the beginning of the second memory block 4 keystrokes needed Alternative V HOW TO INTERPRET RESULTS 1 Any discrepancies between the two blocks are reported on the screen as a double line dump The first of the 2 lines is complete i e it shows 16 bytes The second of the 2 lines shows only those bytes that differ from the corresponding bytes in the first line 2 When screen output stops and a main prompt reappears the number of differences found is reported on the screen AVAILABLE OPTIONS 1 If you want to see some of the bytes preceeding each reported discrepancy you can use the Shift P command to specify the number of previous bytes 1 15 you want displayed with each 2 line discrepancy report 2 After the screen output stops due to autopause or keyboard interrupt you can resume it by pressing the lt spacebar gt once When the end of the specified range is reached pressing the spacebar will result in no change in the current address ALTERNATIVES E The lt End gt key can be pressed to indicate the end of the current region V The key V followed by a digit key 0 to 9 to enter a saved value S The lt spacebar gt can be pressed to accept the default segment value shown at the cursor position R The key R followed by a digi
38. ed 09 hex TAB Use the ALT key plus the numeric keypad decimal digits 0 9 to enter special characters e g ALT 206 gives For a complete definition of all codes in the range 00 FF run the BIOSCHAR program Some useful numeric codes to use with Alt and the resulting characters are 16 204 172 171 Box Drawing Characters 179 196 186 200 218 194 191 201 203 187 213 209 184 214 210 183 4 195 197 180 204 206 185 o 198 216 181 199 215 182 192 193 217 200 202 188 4 1 212 207 190 4 211 208 189 4 MON User s Manual page 14 COMMAND F Fill PURPOSE To fill a region of memory with a constant byte character or string of bytes or characters HOW TO INITIATE from a main prompt 1 Change the current address to the beginning of the memory block you want to fill Use the command to change the current offset OR the command to change the current segment OR the lt PgDn gt or lt PgUp gt command to change the current segment OR the N command to access the memory region you want to fill 2 Press F 3 Type in the hexadecimal address of the end of the memory block you want to fill This requires 4 keystrokes 4 Type in one or more bytes you want to use as the filler Each byte requires two keystrokes 5 Press the lt ENTER gt key When the filling is done MON will signal DONE AVAILABLE OPTIONS 1 If you pref
39. er to enter one or more of the filler bytes in terms of their printable ASCII representations instead of in hexadecimal notation you can switch to ASCII mode by pressing ALT A After entering zero or more ASCII characters you can switch back again to hex mode if desired by pressing ALT H 2 If you declare a byte value to be a wildcard byte using the Shift W command then any occurrences of that byte value in the filler string will NOT overwrite the corresponding bytes in memory In other words the memory bytes at locations that wildcard filler bytes are being sent to will remain unchanged The filler string must be at least 2 bytes long 3 In step 3 you can enter the end address as follows instead of the usual 4 keystrokes a You can press V then a digit key 0 to 9 to enter a saved value b You can press the lt End gt key if you want to enter the end address of the current region MON User s Manual page 15 COMMAND G GoTo PURPOSE To execute a machine language program in memory HOW TO INITIATE from a main prompt 1 Make sure the program you want to execute resides in memory and that its logical end is a RET return instruction 2 If you want to emulate command line parameters use the Shift G command Then press G 3 If your program begins at 0 0100 then you can press lt Home gt then lt Home gt Otherwise type in the hexadecimal segment address 4 keystrokes required and then the hexadecimal offset
40. et OR the command to change the current segment OR the lt PgDn gt or lt PgUp gt command to change the current segment OR the N command to access the memory region you want to overwrite 2 Press L 3 Type in the desired filename then press lt ENTER gt DOS pathnames can be used Wildcards are not allowed HOW TO INTERPRET RESULTS 1 If the file loads successfully you will see the end address of the file written near the left side of the screen 2 If the file cannot be found or cannot be read into memory the computer will beep and an error message will be written on the screen SIDE EFFECTS 1 The memory area into which the file is loaded will be added to MON s list of known memory regions if it is not already there the pathname up to 30 characters will be used as the RegionName the RANGE parameter will be set to the end address of the region and the region s modification count will be set to zero AVAILABLE OPTIONS 1 Low level BIOS level access to the disk instead of the high level DOS level access described above is available by pressing the cursor down down arrow key instead of the filename You then must key in 5 hexadecimal byte values 10 keystrokes needed specifying to BIOS the disk drive number the head number the cylinder track number the first sector number and the number of sectors to read 2 The Shift L command allows you to change the minimum spacing between successive par
41. eturn and linefeed OD OA hex when patch assembling from the keyboard by pressing the lt Enter gt key MON User s Manual Appendix page A 52 Blank lines or all comment lines beginning with a semicolon are allowed and advisable to improve the readability of your program Remember TABS spaces or commas are separators The semicolon begins comments If there is no label put a space or TAB before the mnemonic to indent it from column 1 Upper Lower case are not distinguished in the assembler except in literal ASCII constants Thus the lines SHOW1 MOV AH a and Showl mov ah a are equivalent Numerical Values must begin with a digit 0 to 9 cannot begin with a letter Thus use OFF not FF for hex FF Suffix H denotes hexadecimal D denotes decimal Q or letter O denotes octal B denotes binary Numbers with no suffix are assumed to be decimal unless they begin with digit 0 in which case they are assumed to be hexadecimal An X can precede the suffix letter to avoid ambiguity Example 011XB is binary 11 Without the X would 011B mean binary 11 or hex 11B ASSEMBLER DIRECTIVES PSUEDO OPS The following Assembler Directives are described following the assemble A command SYMBOLS ORG ERROR LIST SOURCE ALIGN Additional assembler directives are Directive amp Operand s Examples Comments DB value s DB 5 6 2 7 23H 0 1 rese
42. f you press lt Home gt when prompted for the destination the region name is used MON User s Manual page 13 e SEARCH After lt Esc gt press S Then type in the character or the string of characters you want to search for then press lt ENTER gt This returns you to the editor with the cursor positioned at the next occurrence of the character or string you typed in If the character or string is not found the computer beeps and the cursor is not moved AVAILABLE SEARCH OPTIONS Hex mode exclusion byte and wildcard byte as described under MON s Search S command f REPEAT SEARCH After lt Esc gt press the lt spacebar gt This repeats the SEARCH command with the same search character or string you typed in before g REPLACE After lt Esc gt press R Then type in the character or the string of characters you want to replace the search string with and then press lt ENTER gt This returns you to the editor Press the lt spacebar gt to replace the SEARCH STRING with the REPLACE STRING AVAILABLE REPLACE OPTION Hex mode press ALT H or normal ASCII mode press ALT A h REPEAT REPLACE Once you have typed in the replace string once you can use it whenever you wish by pressing the lt spacebar gt again immediately following a REPEAT SEARCH operation i TAB STOPS After lt Esc gt press lt Tab gt This lets you see the editor s current TAB settings To change any TAB use the cursor left or right key to move to
43. g any trace mode value 0 to 7 causes the screen to split up into 3 screen windows 2 Pressing lt Esc gt instead of a number 0 to 7 unsplits the screen back into a single window MON User s Manual page 40 COMMAND Shift U Edit a U Format PURPOSE To display or change the definition of a U Format which affects the operation of the unassemble U command HOW TO INITIATE from a main prompt 1 Press Shift U If there is a Custom Macros file in memory you will see Edit U Format ID U_ onthe screen If there is no Custom Macros file in memory you will see an error message to that effect 2 Press the ID character of the U Format you wish to define or edit EFFECTS 1 If the U Format you want to edit already exists in the Custom Macros file you will be put into the editor accessing that format 2 If the U Format you want to define does not already exist in the Custom Macros file you will be put into the editor at the bottom of the file U FORMAT SYNTAX Please see Custom Macro Files later in this document COMMAND Shift W Set Wildcard Byte PURPOSE To examine or change the value of the WILDCARD byte HOW TO INITIATE from a main prompt 1 Press Shift W HOW TO OPERATE 1 To change the value type in a new hexadecimal value can be from 00 to FF hex Two keystrokes are required 2 To disable the wildcard press lt Esc gt instead of typing in a value SIGNIFICANCE OF THE WILDCARD BYTE 1
44. in the file that is nonblank in column one NBC1 The Assembler Macro begins with the upper case letters ASM starting in column one The rest of this line is ignored by MON and can be used for a title and or identifying comments The body begins on the next line and consists of valid assembler directives see the Shift A command all indented at least one column The macro ends with the assembler directive END Each Function Key Definition begins with the two characters Fn starting in column one where n is a digit from 1 to 9 the rest of this line is ignored by MON and can be used for a title and or identifying comments The body consists of indented lines of keycodes The definition ends just before the next line in the file which is nonblank in column one NBC1 Each Unassemble Format Definition begins with the two characters Ux starting in column one where x is any printable character the rest of this line is ignored by MON and can be used for a title and or identifying comments The body consists of indented lines of U Format codes The definition ends just before the next line in the file which is nonblank in column one NBC1 or with a right bracket character whichever comes first To summarize The Item The Body The Item Can There Be More Than Begins Consists Of Ends One of These in the File Initiation at the top of the file Indented before the first No Section Keycodes NBC1 line Assembler with ASM
45. ion RELO 0200 This psuedo op can be useful when for reasons of execution speed you want to be sure that tables or variables are stored in memory on word page or paragraph boundaries MON User s Manual page 9 COMMAND C Copy PURPOSE Copies a block of memory or input ports into another memory area HOW TO INITIATE from a main prompt 1 Change the current address to the address you want to begin from Use the command to change the current offset OR the command to change the current segment OR the Shift l command to change to the I O segment OR the lt PgDn gt or lt PgUp gt command to change the current segment OR the N command to access the memory region you want to copy from 2 Type in the hexadecimal offset address of the end of the block you are copying from 4 keystrokes needed Alternatives E or V 3 Type in the hexadecimal segment address of the beginning of the memory area you are copying to 4 keystrokes needed Alternatives V S or R 4 Type in the hexadecimal offset address of the beginning of the memory area you are copying to 4 keystrokes needed Alternative V HOW TO INTERPRET RESULTS MON says DONE when finished ALTERNATIVES E The lt End gt key can be pressed to indicate the end of the current region V The key V followed by a digit key 0 to 9 to enter a saved value S The lt spacebar gt can be pressed to accept the default segment value shown at the cursor p
46. mal number 8 Keyboard Interrupt Another way of pausing screen output is by pressing any regular keyboard key To resume an interrupted operation simply press the lt spacebar gt MON s Memory Map The example shown here assumes that RELO 1EAS and that an assembly source file in User Segment has just been assembled into RELO 0100 using the default AMACRO System Area User Areas System Area Non Segmented 00000 1EA50 2EA50 3EA50 9FFFF FFFFF Segmented 0000 0000 1EA5 0000 2EA5 0000 3EA5 0000 9000 FFFF F000 FFFF MON Relative RELO 0000 REL1 0000 REL2 0000 BIOS DOS MON UserSegm0 UserSegm 1 User Segm 2 Video ROM Notes q t I Size 272K 64K 64K 64K 227K 384 K Notes e Interprogram Communication Area begins at O0EA5 0130 see page 50 q User s COM program begins at RELO 0100 Assembler s symbol table grows down from RELO FEFOO User program s stack grows down from RELO FFFF User s source program assembly language begins at REL1 0000 Additional regions not shown above typically include the MON HLP file and the Custom Macros File loaded from disk and the Recorder memory region These are somewhere in the User Area The remainder of this manual is a summary of MON s commands Commands are single keystrokes pressed when the program is waiting for user input and is displaying MON s main prompt MON User s Manual
47. mum address in the home segment is 1EA5 FFFF or 2EA4F or O FFFF 3 Each additional 1000 hex increase in segment XXXX corresponds to an increase by one in MON relative segment n and an increase of 10000 hex 64 Kbytes in absolute memory Continuing with the above example the first address beyond the home segment has address 2EA5 0000 or 2EA50 or 1 0000 MON User s Manual page 37 COMMAND Shift N Set Autopause PURPOSE To establish the Autopause parameter i e the maximum number of screen lines MON will output before pausing in some of its commands HOW TO INITIATE from a main prompt 1 Press Shift N You will see the current value of the autopause parameter 2 To change the value type in a new value can be 0 to 99 A double digit number is expected if you type a single digit number without a leading zero you must press lt ENTER3 gt to signal MON that you are done To leave the value unchanged press lt Esc gt INTERPRETATION 1 An autopause value of zero means that autopause is off i e MON will output an unlimited number of lines In other words something other than autopause will have to stop the screen output AVAILABLE OPTIONS 1 A quick equivalent to the Shift N command is obtained simply by pressing any number key 0 to 9 ata main prompt This sets the autopause value with a single keystroke but of course can set values only in the range 0 to 9 COMMAND Shift P Set Previous Bytes
48. n regions it is added to the list with the RegionName of NoName Modify Region with an initial mod count of 80 hex HOW TO TERMINATE THE M COMMAND Press lt Esc gt or lt ENTER gt or any illegal hex or ASCII key AVAILABLE OPTIONS 1 In step 3 above if you prefer to enter new values in terms of their printable ASCII representations instead of in hexadecimal notation you can switch to ASCII mode by pressing ALT A After entering zero or more ASCII characters you can switch back again to hex mode if desired by pressing ALT H 2 Within the MODIFY command you can use the cursor up down left and right keys to move around in memory 3 Ordinarily the MODIFY function operates in the overwrite mode If you want to use the insert mode press the lt Ins gt key For this to work you must have a RANGE value greater than the current address RANGE defines how far into memory the file extends and will increase automatically for every byte you insert type in and will decrease automatically for every byte you delete by means of the lt Del gt key The insert mode cannot be used when accessing output ports Pressing lt Ins gt again returns you to overwrite mode MON User s Manual page 21 COMMAND N Named Regions PURPOSE To display or change the memory region currently being accessed by MON HOW TO INITIATE from a main prompt 1 Press N This shows the memory region currently being accessed if any 2 OPTIO
49. nstruction appear at the left of the screen This means that they now reside in memory The current address is advanced to the location beyond the instruction 2 If the machine beeps an error was found The current address is not advanced and so you can immediately re type the correct instruction HOW TO TERMINATE ASSEMBLY Use the pseudo op END or press the lt Esc gt key MON User s Manual page 7 Assembler Directives Psuedo Ops Each assembler directive must be indented at least one space or TAB from the left column and can appear in source files or in assembler macro files Brackets enclose optional items Directives apply to the A command both in the source file and patch modes except those marked SOURCE MODE ONLY Single digit segment addresses are interpreted as MON relative segment numbers e g 0 means RELO 1 means RELI etc SYMBOLS segment offset1 offset2 This psuedo op clears the assembler s symbol table If no addresses are specified the new table will begin at RELO FFO0O and grow downward from there If one address offset2 is specified the new symbol table will begin at that address and grow downward from there If two addresses are specified the symbol table will limited to the range from the offset1 to offset2 The default memory organization in segment RELO for assembling source files is as depicted here Object Program grows gt lt lt grows Symbol Table RELO
50. o the most recent End of definition marks the point in a U Format definition to return to when a is reached P forces a pause in the screen output MON s main prompt abcd_ changes the current offset address to abcd must be 4 hexadecimal digits Vn changes the current offset address to saved value Vn n 0 to 9 SVn stores the current offset address into save variable Vn n 0 to 9 SBVn _ stores the current byte into save variable Vn n 0 to 9 SWVzn stores the current word into save variable Vn n 0 to 9 SDVn stores the current doubleword into save variable Vn n 0 to 9 Rnn repeat the U codes within parentheses nn times nn 2 to 99 RVn repeat the U codes within parentheses Vn times n 0 to 9 Note The variables Vn used above are the same as described in the section Communication With Other Programs Sample U Format UK Disk Directory A8 A3 B T35 Attributes WWWWW T35 Reserved W W W T35 Time Date 1st cluster D T35 File Size MON User s Manual page 50 Communication With Other Programs A special memory area is defined beginning at hex location 0130 in MON s segment i e in REL 1 The area is 40 bytes long and stores the values of 10 save variables denoted by VO V1 V9 This area is the same area used for variables VO V9 in U Formats Each variable is allotted 4 bytes 0130 0133 0134 0137 0138 013B 013C 013F 0140 0143 0144 0
51. of memory use and execute R 3 R4 or R5 to purge the memory before it reaches its 64K byte limit RECORDER OPERATIONS Key Action Name Description Comments OFF RWD 1 Record Turns the recorder on MON s prompt character no no becomes instead of Stop Pauses or stops the recorder yes no Discard Rewinds the recorder without saving anything yes yes Write to Disk Writes the recorder memory to disk or to the yes yes printer if you use the destination name PRN 5 Edit Creates a memory region of the recorder yes yes memory and puts you into the editor so that you can examine annotate and save the log file The column OFF indicates whether the action turns the recorder off RWD indicates whether the action causes a rewind of the recorder ADDITIONAL RECORDER DETAILS MON User s Manual page 24 MON chooses a section of memory to use for the 64K recorder memory segment but does not register this section in the list of known regions Therefore you do not know its location For this reason it is recommended that you purge the recorder memory by executing recorder action R3 R4 or R5 before you create any new memory regions with the lt Ins gt L M or E commands For the same reason the J command may not put you into a clear memory area It is recommended that you purge the recorder memory by executing recorder action R 3 R 4 or R5 before you use the J command
52. om the beginning by pressing lt Fn gt again ERROR CONDITION 1 If there is no Custom Macros file or no definition in it for the function key you press an error message to that effect will appear on the screen Create the file or definition using the E edit command COMMAND Shift lt Fn gt Define a Macro lt Fn gt is function key lt F1 gt to lt F9 gt PURPOSE To define a function key macro HOW TO EXECUTE from a main prompt 1 Make sure that a Custom Macros file exists in the list of known memory regions If there is none you can a create a new file with the E edit command b load an existing macro file from disk with the L load command or c redefine one of the existing regions as the custom macro region by redefining its Access Key as the asterisk 2 Press Shift lt Fn gt where lt Fn gt is a function key lt F1 gt to lt F9 gt If a definition for the selected function key already exists in the Custom Macros file it will appear on the screen now If no definition for the selected function key currently exists you will be put into the editor at the bottom of the Custom Macros file 3 Use editor commands to create or change the definition as desired The required Keycodes Syntax is detailed below 4 Exit from the editor and the Custom Macros file by pressing the lt Esc gt key twice MON User s Manual page 47 KEYCODES SYNTAX Here is a sample lt Fn gt definition for lt F2
53. or position c lt Backspace gt key deletes the character before the cursor position d lt Tab gt key inserts or overwrites a TAB character hex 09 The editor displays a TAB by expanding it into 1 or more spaces tab stops initially are 8 columns apart e Pressing a character key causes that character to be added to the file at the original cursor position and the cursor to be advanced by one position 3 User definable macros a Function keys lt F1 gt to lt F9 gt can be used for whatever custom sequences of keystrokes you want to program These macros can be used either inside or outside of the editor See the Shift lt Fn gt command for information on how to define a function key macro 4 Editor Command Level In the editor pressing lt Esc gt once brings you to the editor command level The file s name modification count and memory range and the cursor s line and column numbers are displayed along with the editor prompt Editor Command At this point you can do any of the following a Press lt Esc gt again This brings you out of the editor entirely and to a main MON prompt b Press E This returns you the editor and the file you were working on c Press C D P R W S lt Tab gt or lt spacebar gt which initiates one of the escape commands d Press H or any other key to show an editor Help screen 5 Escape Commands are initiated from the Editor Command Level see 4 above a DELETE BLOCK After
54. ore you use the G GOTO command to test run a COM program What are Command Line Parameters Suppose you have a program XYZ COM To run it from a DOS prompt you could type XYZ 1 P2 where 1 and P2 are command line parameters or switches that XYZ has been programmed to act on in some way DOS places anything on the command line that follows the program name here the string 1 P2 into memory starting at offset address 0081 hex It then loads the program XYZ COM into memory starting at offset address 0100 hex and turns over control to goes to program XYZ at offset location 0100 hex To emulate this DOS behavior in MON the Shift G command provides an easy way for you to put command line parameters into the same memory area below the COM program that DOS would use HOW TO USE 1 Press Shift G 2 Type the command string you want the COM program to see 3 Press lt Enter gt 4 GoTo G command your COM program at RELO 0100 EFFECTS The string you type is placed into memory begining at RELO 0081 and its byte count is placed in RELO 0080 Step 4 then executes the COM program and your COM program sees the command line parameters in memory at the same location it would see them if the program had been run from DOS MON User s Manual page 34 COMMAND Shift I T O Memory Toggle PURPOSE To access I O ports instead of memory addresses in certain MON commands i e the COPY DUMP and MOD
55. osition R The key R followed by a digit 0 to 9 to enter a MON relative segment value MON User s Manual page 10 COMMAND D Dump or Display PURPOSE Display Dump contents of memory or input ports HOW TO INITIATE from a main prompt 1 Change the current address to the address you want to begin from Use the command to change the current offset OR the command to change the current segment OR the lt PgDn gt or lt PgUp gt command to change the current segment OR the Shift l command to change to the I O segment OR the N command to access the memory region you want to display 2 Determine how when you want the display to stop Use the Shift N command to set the autopause value OR the Shift R command to set the RANGE OR be ready to press lt Esc gt or other key to interrupt the output 3 Press D HOW TO INTERPRET RESULTS 1 A typical dump line consists of an address at the left of the screen 16 bytes showing memory or input port contents and 16 ASCII characters at the right of the screen 2 The leftmost byte if 16 are shown always has a hex address ending in 0 Intel calls this a paragraph boundary The final address digits of the 16 bytes are always 0123 4567 89AB CDEF Bytes are clustered into groups of 4 as suggested here this is designed to help you identify byte addresses easily clusters always begin at addresses ending with 0 4 8 or 3 The first line of a dump may contain fewer
56. page 5 COMMAND A Assemble Assemble a Source File PURPOSE To assemble an assembly language source program into an executable machine language object program a COM file HOW TO INITIATE 1 Make sure your source program is in memory beginning at REL1 0000 Use the L command to load in the file from disk to memory OR the E command to create the file in memory 2 The source program should end with an END statement followed by a blank line 3 Turn off AUTOPAUSE press zero from a main prompt 4 Press A then lt Home gt HOW TO INTERPRET RESULTS 1 Zf the computer beeps an error has been found You will be returned to the editor with the cursor positioned at the line where the error was found The error message will appear at the bottom of the screen Make the required change s escape from the editor and re initiate the A command as described above in step 4 2 If no error is found a listing will scroll by on the screen during pass 2 of the assembly At the end you will see a message that you are Now Accessing the newly created object program in memory Unless you changed the default see below the object program will begin at 0 0100 HOW TO USE THE OBJECT PROGRAM 1 If you want to save the object program to disk as a COM program press W write command then type in the filename you want to give the program Suggested filename extension COM 2 If you want to execute your object program
57. press G goto command then lt Home gt then lt Home gt again 3 If you want to trace execute your object program use the T trace command AVAILABLE ASSEMBLER OPTIONS 1 Most assembler options are determined by pseudo ops in a macro file called AMACRO You can examine or change MON s built in AMACRO file by means of the Shift A command Initially the default file contains the lines SYMBOLS inz symbol table LWA 0 FF00 FWA means ORG 0 0100H FWA object program ni E RODIT beginning address LIST LWA means end SOURCE 1 0 FWA source file address END The first line reinitializes the symbol table makes MON forget any symbolic names used in a previous assembly and establishes the memory address where the symbol table will begin The ORG line establishes the memory address where the object program will begin The ERROR line tells MON what to do if it encounters an assembly error The LIST line causes the assembly listing to be scrolled by on the screen during pass 2 of the assembly The SOURCE pseudo op tells MON where in memory to find the source file MON User s Manual page 6 Details on these and other psuedo ops are given in the section below on Assembler Directives 2 If you load into memory a Custom Macros file which contains an ASM section then MON will use the information it finds there instead of in its built in default AMACRO How to get an ASSEMBLY LIST of your program
58. ptions page 30 Shift B Set Breakpoints page 31 Shift D Set Dump Options page 32 Shift G Set GoTo Parameters page 33 Shift I I O Memory Toggle page 34 Shift J Change the Segment Adder page 34 Shift K Clear the Screen page 35 Shift L Set Load Parameter page 35 Shift M Set Memory Display Mode page 36 Shift N Set Autopause page 37 Shift P Set Previous Bytes page 37 Shift R Set RANGE page 38 Shift T Set Trace Mode page 39 Shift U Define U Format page40 Shift W Set Wildcard Byte page 40 Shift X Set Exclusion Byte page 41 Other Commands EEE Set Offset Address page 41 Falaka Set Current Segment page 42 TM tales desl eai Set Autopause Value page 42 period Save Offset 004 page 42 lt Home gt Move to Beginning page 43 lt Ins gt Define New Region page 43 lt End gt Move to End 4 page 43 lt CrsrDn gt One Line Dump page 44 lt CrsrUp gt Decrease Offset page 44 lt CrsrLeft gt Repetitive One Line Dump page 44 lt PgUp gt Decrease Segment page 45 lt PgDn gt Increase Segment
59. r key for the format you want If there is no Custom Macros file in memory the only legal choices are 0 which results in source code in the screen output and 1 or U which results in object and source code in the screen output 5 If you have a Custom Macros file in memory you can use in step 4 any ID key for which you have a U format definition in that file If you define format UO or U1 or UU inthe Custom Macros file then that definition will override the default meaning described above AVAILABLE OPTIONS 1 The Shift U command allows you to define custom U formats which gives you tremendous flexibility in displaying contents of memory or I O ports MON User s Manual page 28 COMMAND V Verify PURPOSE Verifies compares a block of memory with another memory area HOW TO INITIATE from a main prompt 1 Determine how when you want the display to stop Use the Shift N command to set the autopause value OR Be ready to press lt Esc gt or other key to interrupt the output 2 Change the current address to the beginning address of the first block you want to compare Use the command to change the current offset OR the command to change the current segment OR the Shift l command to change to the I O segment OR the N command to access the memory region you want to compare 3 Type in the hexadecimal offset address of the end of the first block you are comparing 4 keystrokes needed Alternatives E or V 4 Typ
60. rom a main prompt press Shift T then lt Esc gt Alternatively invoking HELP or doing any editor operation also restores the screen to a single window THE FINE PRINT The trace command works by setting the processor s TF bit trace flag to 1 This causes the processor to be interrupted after every instruction Tracing is suspended during hardware or software interrupts Trace execution of a program is slower by several orders of magnitude than GOTO execution of the same program COMMAND U Unassemble PURPOSE To unassemble disassemble a machine language object program into an assembly language source program This command also allows dumping of memory or I O ports with greater custom formatting capability than the D dump command HOW TO INITIATE from a main prompt 1 Change the current address to the object program address you want to begin unassembling from Use the command to change the current offset OR the command to change the current segment OR the lt PgDn gt or lt PgUp gt command to change the current segment OR the N command to access the memory region you want to unassemble 2 Determine how when you want the display to stop Use the Shift N command to set the autopause value OR the Shift R command to set the RANGE OR Be ready to press lt Esc gt or other key to interrupt the output 3 Press U You will see on the screen the header UN ASSEMBLE using format U_ 4 Press the ID characte
61. rs which can affect several different MON commands COMMAND Shift A Set Assembler Options PURPOSE To examine or modify options for MON s assembler HOW TO INITIATE from a main prompt 1 Press Shift A 2 Use standard editor keys to move around in the file delete or add characters etc HOW TO EXIT FROM THE SHIFT A COMMAND 1 Press the lt Esc gt key twice to return to MON s main prompt See the A assemble command for explanations of the various options that can be used in this AMACRO file WHERE IS THE ASSEMBLER OPTIONS FILE 1 MON has a built in edit file which has the initial defaults described under the A command Executing the Shift A command accesses this built in file and allows you to edit it using editor commands just as you would edit any other ASCII file 2 To allow you to customize the assembler defaults to your own preferences MON will always search the Custom Macros file if one exists in its list of known regions If the file is found and if the file contains an ASM section MON will use that section as the assembler options file instead of the built in file The same command Shift A accesses both files the ASM section of the Custom Macros file if found otherwise the built in file MON User s Manual page 31 COMMAND Shift B Set Breakpoints PURPOSE To examine or modify the BREAKPOINTS to be used when trace executing a program T command HOW TO INITIATE from a main prompt 1
62. rves memory for and initializes byte variables DB denotes the value is unknown at assembly time STRING DB Hello A DB string can be any number of characters long DW value s DW 3400H 7 23H reserves memory for and initializes word variables DW denotes the value is unknown at assembly time CODE DW AB A DW string must be exactly two characters long In either of these assembler directives value may be replaced by n DUP value where n is a numeric constant Examples Meaning DB 5 DUP 7 same as DB7 7 7 7 7 Reserves amp initializes 5 bytes DB 1000 DUP a same as 1000 lines of DB a Reserves and initializes 1000 bytes DW 16H DUP 5 same as 22 lines of DW 5 Reserves amp initializes 44 bytes MON initializes these locations to zeroes but other assemblers may initialize them differently Additional assembler directives are Directive amp Operand s Examples Comments LABEL EQU value FIVE EQU 5 Useful for defining symbolic constants MOV AL FIVE Equivalent to MOV AL 5 END END Takes no label or operands END must be followed by a carriage return and linefeed MON User s Manual Appendix page A 53 THE IF CONSTRUCT MON s assembler allows a conditional construct of the form IF condition instruction where the keyword IF occupies the position in the line of the usual mnemonic The condition is one of A AE B BE C E G L LE P PE S Z O NA NAE INB INBE INC INE ING
63. s by 0010 hex This undoes the address change caused by the lt CrsrDn gt command HOW TO INITIATE from a main prompt 1 Press the lt CrsrUp gt cursor up key COMMAND lt CrsrLeft gt Repetitive One Line Dump PURPOSE To repetitively display a one line dump HOW TO INITIATE from a main prompt 1 Change the current address to the memory location whose contents you want to display Use the command to change the current offset OR the command to change the current segment OR the lt PgDn gt or lt PgUp gt command to change the current segment OR the Shift l command to access input ports not memory locations OR the N command to access the memory region you want to display 2 Press the lt CrsrLft gt cursor left arrow key COMMENTS 1 This command allows you to examine a memory location or input port in real time so that you can watch how it changes in response to external stimuli Press the lt Esc gt key to exit 2 The command is also useful for monitoring the values of timer bytes which are maintained by interrupts and BIOS or DOS routines MON User s Manual page 45 COMMAND lt PgUp gt Decrease Segment PURPOSE To decrease the current segment address by 1000 hex i e to decrease the current MON relative segment by 1 HOW TO INITIATE from a main prompt 1 Press the lt PgUp gt key OTHER EFFECTS COMMAND lt PgDn gt Increase Segment PURPOSE To increase the current
64. s is written to the designated location MON User s Manual Appendix page A 51 Appendix A Assembler Syntax The assembler the A command allows you to translate assembly language source statements into executable machine language object code Whether assembling a source file or patch assembling the required syntax for source statements is the same LINE FORMAT Each source statement is a line of ASCII text arranged as follows LABEL MNEMONIC OPERAND S COMMENTS example SHOW MOV AL SI get limit value The LABEL if present must begin in the very first column of the line not preceeded by a space or TAB It must begin with a letter consist of no more than 10 characters and include only letters and or digits The colon is optional The MNEMONIC if present must not begin in column 1 That is it must be preceeded by at least one space or TAB character Legal mnemonics are either 8088 8086 instructions listed on page A 3 or assembler directives also called psuedo ops listed on page A 2 The number and types of OPERANDS required depends on the mnemonic Two or more operands must be separated by at least one space or TAB or other operand separator but no space or TAB should appear within an operand The permissible forms of operands are Operand Form Examples Notes Comments i Numerical constant 5 17H 29635 see Numerical Values on the next page ii Register
65. saved value VO to V9 will be entered MON User s Manual page 42 COMMAND Set Current Segment PURPOSE To change the SEGMENT part of MON s current address HOW TO USE from a main prompt 1 Press the plus key 2 Type in the new hexadecimal address 4 keystrokes needed AVAILABLE OPTIONS 1 If you press lt Home gt instead of a hexadecimal number MON s home segment will be entered 2 If you press V then a digit 0 to 9 instead of a hexadecimal number the saved value VO to V9 will be entered 3 If you press R then a digit 0 to 9 instead of a hexadecimal number the MON Relative Segment RELO to REL9 will be entered 4 lf you press the letter I instead of a hexadecimal number the segment changes to I O i e the I O ports are accessed instead of memory locations COMMAND n Set Autopause Value where n is any digit 0 to 9 PURPOSE To establish the Autopause parameter i e the maximum number of screen lines MON will output before pausing in some of its commands HOW TO INITIATE from a main prompt 1 Press a digit key 0 to 9 INTERPRETATION 1 An autopause value of zero means that autopause is off i e MON will output an unlimited number of lines In other words something other than autopause will have to stop the screen output AVAILABLE OPTIONS 1 The Shift N command is available to allow you to set AUTOPAUSE to a value greater than 9 COMMAND period Save Offset PURPOSE
66. se the N command to access the file you want c For a file on disk but not yet in memory Change the current address to the memory location where you want the file to begin suggested REL1 0000 and use the L command to load the file from disk If there are other files in memory use the J command to position the current address away from them before using the L command 2 Press E SIDE EFFECTS 1 Each editor action which alters the file increments the memory region s modification count If the memory region is not initially in MON s list of Known regions it is added to the list with the Region Name NoName Edit File HOW TO EXIT FROM THE EDITOR Press lt Esc gt twice to exit from the editor and return to a MON main prompt MON User s Manual page 12 EDITOR OPERATIONS 1 Cursor and Screen Positioning a Cursor keys move the cursor one position left right up down b lt Home gt and lt End gt move the cursor to the beginning or end of the line c Control Left and Control Right move the cursor 16 positions horizontally d lt PgUp gt and lt PgDn gt move the cursor up or down 24 lines e Control lt PgUp gt or lt PgDn gt move cursor to the beginning or end of the file 2 Inserting Deleting and Overwriting Characters a lt Ins gt changes from INSERT to OVERSTRIKE mode or vice versa The cursor appearance changes to indicate the mode b lt Del gt key deletes a single character at the current curs
67. t 0 to 9 to enter a MON relative segment value MON User s Manual page 29 COMMAND W Write PURPOSE To write a block of memory to disk or to the printer HOW TO INITIATE from a main prompt 1 Change the current address to the beginning of the block you want to write Use the command to change the current offset OR the command to change the current segment OR the lt PgDn gt or lt PgUp gt command to change the current segment OR the N command to access the memory region you want to write 2 Use the Shift R command if necessary to set RANGE to the end address of the block you want to write Not necessary if you used the N command in step 1 3 If you did use the N command in step 1 you may have to press the lt Home gt key to bring the current address to the beginning of the region 4 Press W 5 Type in the desired filename then press lt ENTER gt DOS pathnames can be used The reserved name PRN means the printer instead of a disk file HOW TO INTERPRET RESULTS 1 If the file transfers successfully MON writes DONE on the screen after the filename 2 If the specified disk or pathname cannot be found or if the file cannot be written e g a file of the same name already exists on disk and it is write protected the computer will beep and an error message will appear on the screen 3 If the memory span you attempt to write is within a known memory region but it is smaller than the kno
68. the H screen When you are viewing any screen in HELP you can press fin order to do this Home or 00 See the Help Index Screen i e screen 00 Any Letter X See Help Screen X if screen X exists Two Digits ab See Help Screen ab if screen ab exists Lor PgDn or space See the logically next Help Screen T or PgUp See the logically previous Help Screen pi See the Help Screen you viewed before in time S gt See the Help Screen you viewed next in time S Esc Exit from HELP These keys allow you to browse through the entire HELP file or to go back and forth through pages of a multi screen topic S The amp and keys allow you to retrace your sequence of steps through the Help system during this visit except it skips over screen 00 POSSIBLE DIFFICULTIES MON s Help function uses a separate file MON HLP If the file has not already been loaded into memory or if it has an access key other than H MON asks your permission to load MON HLP at this time Press Y to allow this action If it cannot find the file or if there is no more room in memory for the file MON writes a message to this effect on the screen Suggestion Use the DOS command APPEND to let DOS know where to find the file MODIFYING MON HLP You can annotate or otherwise modify the help file if you wish 1 Make a backup copy of the original MON HLP file using another name such as MONORIG HLP
69. the desired position and press the lt spacebar gt The lt spacebar gt toggles the position s TAB status making it a TAB stop if it was not before or removing the TAB from that position if one was there before At this point you can also press L or W to load or write the TAB settings to or from disk To return to the Editor Command Level press lt Esc gt once MON s editor is a simple non wrapping line editor suitable for preparing assembly langage source files or for editing ASCII text files such as AUTOEXEC BAT CONFIG SYS WIN INI etc The maximum file size is 64K bytes But you can have multiple files in memory at the same time and easily switch between them by exiting to MON s main prompt and using the N command The maximum offset address for any character in the edit file is FFFF hex Therefore to realize the maximum possible file size 64 Kbytes you should start the file at offset address OOOOH The maximum line length is 254 characters Only 80 characters are visible on the screen at any time Special Characters You can include any character hex 00 to FF in the file though only the standard printable characters hex 20 to 7E may be immediately recognizable Codes outside the printable range are usually regarded as control codes or special characters and should not be used in general purpose ASCII text files The common exceptions and the exceptions in MON s editor are OD hex carriage return OA hex line fe
70. ts of a multisegment file MON User s Manual page 20 COMMAND M Modify PURPOSE To modify the contents of memory or write into output ports HOW TO INITIATE from a main prompt 1 1 Change the current address to the first location you want to modify Use the command to change the current offset OR the command to change the current segment OR the lt PgDn gt or lt PgUp gt command to change the current segment OR the Shift l command to change to the I O segment OR the N command to access the memory region you want to overwrite 2 Press M 3 Type in the new hexadecimal byte value you want at that location This requires two keystrokes for each byte value 4 After you type each byte the cursor advances to the next memory location so you can enter a series of values into consecutive memory locations by simply repeating step 3 for as many bytes as you want HOW TO INTERPRET RESULTS 1 When modifying memory but not when writing to output ports MON does a read check after each write If the value s you type in remain s on the screen then they have been successfully stored into memory If storage is unsuccessful e g the memory location is ROM or unimplemented the computer will beep and the screen will show the actual contents of memory SIDE EFFECTS 1 Each byte modified with this command increments the memory region s modification count If the memory region is not initially in MON s list of know
71. us paragraph Named regions can be in the I O space I O segment or in the memory space Note Before creating a new memory region see caution 4 below THE MOD COUNT After a disk I O operation the loaded or written file is made a region with mod count 00 When a region is created in a non disk operation the mod count is initialized to 80 hex Any edit modify operations then increase the region s mod count until the maximum value of FF is reached The bottom line is this If the MOD count is nonzero the region is not yet saved to disk Thus before exiting MON you may want to execute the N N command to see whether there are any unsaved files or regions that you want to write to disk before exiting LIMITS AND CAUTIONS 1 The maximum number of known regions is 15 If any MON operation attempts to add a 16th region the last entry on the list will be overwritten with the new one MON User s Manual page 22 2 The region name is limited to 30 characters maximum 3 The modification count can go as high as FF hex If additional modifications are made the count remains at FF 4 It is recommended that you empty the recorder memory Press R then 3 from a main prompt before you create a new memory region This precaution is necessary because you do not know what part of memory MON has decided to use for the recorder memory MON User s Manual page 23 COMMAND R Recorder PURPOSE To control MON s recorder facility Wh
72. usion byte is considered to match any byte value in memory EXCEPT the value of the exclusion byte MON User s Manual page 26 COMMAND T Trace PURPOSE To trace execute a machine language object program in memory for study or debugging purposes HOW TO INITIATE from a main prompt 1 Press T 2 Hold down the lt Home gt key or press lt Home gt 13 times until the cursor goes all the way across the screen and reappars at the left side This initializes all the registers to zero except CS DS ES SS MON s home segment RELO and IP 0100 Skip this step if you want to resume tracing without restarting the program from the beginning 3 Press lt ENTER gt This arms the lt spacebar gt for tracing splits the screen into three windows and returns you to a main MON prompt 4 You now also see on the screen a summary of 3 important options for tracing the autopause value the trace mode and the breakpoints You can change any or all of these the commands are respectively Shift N Shift T and Shift B or proceed directly to step 5 5 Press the lt spacebar gt This initiates trace execution of the program HOW TO INTERPRET RESULTS The upper screen window is for any screen output that the traced program may produce The center window is the main window for MON output as usual During tracing this window also shows 1 if enabled the log of register and flag values 2 if enabled the log of instructions e
73. wn region the computer will beep and a warning message will appear reminding you that you are about to write only PART of the file If this is what you want you can proceed with step 5 above the original file on disk will be overwritten with the shorter part file If this is not what you want you can abort the operation by pressing the lt Esc gt key SIDE EFFECTS 1 Once written the pathname up to 30 characters will be added to MON s list of known memory regions and the modification count will be set to zero AVAILABLE OPTIONS 1 Low level BIOS level access to the disk instead of the high level DOS level access described above is available by pressing the cursor down down arrow key instead of the filename You then must key in 5 hexadecimal byte values 10 keystrokes needed specifying to BIOS the disk drive number the head number the cylinder track number the first sector number and the number of sectors to read WARNING Because it is easy to trash a DOS disk with this BIOS level write command MON asks you Are you sure Press Y to confirm Unless you are absolutely sure of what you are doing do not use this BIOS level write option MON User s Manual page 30 Shift Commands Many Shift commands allow you to set parameters for the corresponding unshifted command For example the Shift A command sets options for the Assembler the A command Other Shift commands allow you to set paramete
74. write lt TAB gt or lt tab gt LIMITATIONS 1 A function key macro cannot invoke another macro 2 Do not press any lt Fn gt when editing the Custom Macros file This could confuse MON if the characters in the definition of lt Fn gt moved around in memory as it was trying to interpret those characters 3 If a MON error is encountered when an lt Fn gt macro is being run the macro is turned off and the computer beeps To see which keystroke in the macro produced the error press E editor MON will have set its current address to the position in the Custom Macro file where the error occurred so that you can see where it is and take appropriate remedial action MON User s Manual page 48 Custom Macros File You can customize MON s operations in a number of ways through a Custom Macros File This is an ASCII text file organized as follows Initiation Section Assembler MACRO Function Key Definitions and lt the first section in the file lt Definitions in these sections lt can appear in any order Unassemble Format Definitions lt and sections can be split The Initiation Section defines the MON commands to be executed when MON is first invoked from DOS This macro filename is specified as a slash option on the DOS command line The initiation section begins on the very first nonblank line in the file and consists of indented lines of keycodes It ends just before the first line
75. xecuted 3 An End of Trace message when the terminating RET instruction is encountered The lower screen window if enabled shows the current register values and stack contents of the traced program The IP register shows the address of the next instruction that is about to be executed During a pause the next instruction is previewed in this window Items marked if enabled can be enabled or disabled with the Shift T command AVAILABLE OPTIONS 1 The trace mode trace options can be set with the Shift T command 2 After screen output stops due to autopause breakpoint or keyboard interrupt you can resume it by pressing the lt spacebar gt once 3 Before resuming the trace you can do other MON commands e g examine memory If any of these other commands redirects the spacebar so that pressing the lt spacebar gt no longer causes tracing you can press T then lt ENTERs to re arm the spacebar for tracing OPERATING NOTES 1 To trace a only subroutine within a larger program simply type in the subroutine s starting address for the IP register value in initiation step 2 above instead of setting IP equal to 0100 with the lt Home gt key MON User s Manual page 27 2 If the subroutine needs certain register inputs these values can similarly be keyed in in initiation step 2 above instead of accepting the default lt Home gt key value of zero 3 To undo the split screen caused by the T command you can f

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