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CP/M V2.2 Application Note 01, 2/20/82 The CCP Auto-Load Feature Copyright 1982 by Digital Reserch CP/M is a registered trademark of Digital Research. DDT is a trademark of Digital Research. Compiled November 1982 Applicable products and version numbers: CP/M V1.4, V2.0, V2.1, and V2.2 Program: CCP (Console Command Processor) Usually, you interact with the CP/M CCP following the sign-on prompt. With the CCP Auto Load feature, CP/M executes an initial program immediately after loading the operating system. Under usual operation, the CCP receives control from the BIOS upon a warm or cold boot. The beginning of the CCP module contains a two-element jump vector and a command line that takes the form: CCP: JMP CCPSTART ;START THE CONSOLE PROCESSOR JMP CCPCLEAR ;CLEAR THE INITIAL COMMAND DB 127 ;MAXIMUM COMMAND LENGTH CL: DB 0 ;COMMAND LENGTH DB ' ' ;8 BLANK CHARACTERS DB ' ' ; " DB 'COPYRIGHT...' ;COPYRIGHT NOTICE If control is transferred to location CCP (address 3400H in a 20K CP/M), the console processor examines the command length at location CL (3407H in a 20K CP/M). If the command length byte is zero, then you receive the sign-on prompt and the CCP waits for console input. If the command length byte is not zero, the CCP assumes an initial command has already been entered. The CCP executes the command on each cold or warm boot if control is transferred to location CCP. However, if control is transferred to location CCP+3 (JMP CCPCLEAR), the initial command is cleared and the program enters the CCP at the command line level, displaying the default drive prompt. Specify the length of the initial command using a nonzero CL byte. The command must be followed by a terminating zero. CP/M executes the command following that CL byte. Although only 16 blank spaces are provided, you can move the Digital Research copyright notice for more spaces. You can initialize the command line of the CCP on the operating system tracks or in the relocatable image within the MOVCPM data area. The initial command executes in distributed or reconfigured CP/M systems. Following SYSGEN and SAVE commands, save the CP/M memory image above the cold boot loader code starting at location (980H). If the system boot routines require more than 80H bytes, the CCP code begins at location 0A00H. Modifying MOVCPM.COM is similar to modifying the CCP. The difference is that the CCP always begins at location 0A00H. The following procedure uses DDT to modify the CCP, allowing execution of the initial command DIR after each warm or cold boot. A>movcpm * * CONSTRUCTING 64K CP/M Vers. 2.2 READY FOR "SYSGEN" OR "SAVE 35 CPM64.COM A>save 35 cpm64.com A>ddt cpm64.com DDT VERS 2.2 NEXT PC 2400 0100 -d980 0980 C3 5C E7 C3 58 E7 7F 00 20 20 20 20 20 20 20 20 ...X... 0990 20 20 20 20 20 20 20 20 43 4F 50 59 52 49 47 48 COPYRIGH 09A0 54 20 28 43 29 20 31 39 37 39 2C 20 44 49 47 49 T (C) 1979, DIGI 09B0 54 41 4C 20 52 45 53 45 41 52 43 48 20 20 00 00 TAL RESEARCH .. 09C0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ -s987 0987 00 3 0988 20 44 0989 20 49 098A 20 52 098B 20 0 098C 20 . -d980 0980 C3 5C E7 C3 58 E7 7F 03 44 49 52 00 20 20 20 20 ...X...DIR. 0990 20 20 20 20 20 20 20 20 43 4F 50 59 52 49 47 48 COPYRIGH 09A0 54 20 28 43 29 20 31 39 37 39 2C 20 44 49 47 49 T (C) 1979, DIGI 09B0 54 41 4C 20 52 45 53 45 41 52 43 48 20 20 00 00 TAL RESEARCH .. 09C0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ -g0 A>save 35 cpm64.com A>sysgen cpm64.com SYSGEN VER 2.0 DESTINATION DRIVE NAME (OR RETURN TO REBOOT)b DESTINATION ON B, THEN TYPE RETURN FUNCTION COMPLETE DESTINATION DRIVE NAME (OR RETURN TO REBOOT) Licensed users are granted the right to include these modifications in CP/M software. CP/M V2.2 Application Note 02, 2/20/82 Reversing the BACKSPACE and RUBOUT Key Functions and Making RUBOUT Identical to BACKSPACE Copyright 1982 by Digital Research CP/M is a registered trademark of Digital Research. DDT and SID are trademarks of Digital Research. Compiled November 1982 Applicable products and version numbers: CP/M V2.1 and V2.2 Program: BDOS In the following code segment procedures, addresses given are hexadecimal offsets from the base of the CP/M system. The CCP is usually located at 980H but can be located at A00H if a two-sector boot is used. You can assemble the patch for your size memory system. The cpmbase equals the BDOS entry point address at locations 6 and 7 in the base page of memory minus 806H. You must change this entry point address when you load DDT or SID . Under DDT or SID, follow the jump at location 5 until an address is found with a least significant digit of 6. In the following example, the cpmbase would be E506H-806H or DD00H. 0005 JMP CD00 CD00 JMP D3A4 D3A4 XTHL D3A5 SHLD E452 D3A8 XTHL D3A9 JMP E506 Procedure to reverse the BACKSPACE and RUBOUT key functions: Patch into the SYSGEN or MOVCPM image exactly as you would patch in a new version of your BIOS, using the DDT i command followed by the DDT r command. You can use the same offset as your custom BIOS and install the following code: cpmbase equ ? ;subtrack 806h from address at location 6 org cpmbase + 0A02h cpi 7fh ;was cpi 08h org cpmbase + 0A16h cpi 08h ;was cpi 7fh Or, you can install the above procedure directly into MOVCPM if you have MOVCPM.COM on your system disk. The patch is applied automatically to any size system that you build using MOVCPM. Make a back-up copy of MOVCPM.COM before using DDT to make the following changes: A>ddt movcpm.com DDT VERS 2.2 NEXT PC 2700 0100 -l1402 1402 CPI 08 1404 JNZ 0A16 1407 MOV A,B 1408 ORA A 1409 JZ 09EF 140C DCR B 140D LDA 0B0C 1410 STA 0B0A 1413 JMP 0A70 1416 CPI 7F 1418 JNZ 0A26 -s1403 1403 08 7f 1404 C2 . -s1417 1417 7f 8 1418 C2 . -g0 A>save 38 movcpm1.com Use the new program MOVCPM1.COM in place of MOVCPM.COM. The BACKSPACE and RUBOUT key functions are reversed for any CP/M system generated with MOVCPM1.COM. Procedure to make RUBOUT identical to BACKSPACE: Before you install this patch, the code at cpmbase + 0A1Bh should read: mov a,b ora a jz cpmbase + 09EFh mov a,m dcr b dcx h jmp cpmbase + 0AA9h Patch into the SYSGEN or MOVCPM image exactly as you would patch in a new version of your BIOS, using the DDT i command followed by the DDT r command. Use the same offset as your custom BIOS and install the following code: cpmbase equ ? ; ; org cpmbase + 0A1Bh ; mvi a,8h jmp cpmbase + 0A07h end Or, you can install the above procedure directly into MOVCPM if you have MOVCPM.COM on your system disk. The patch is installed automatically in any size system that you build using MOVCPM. Make a back-up copy of MOVCPM.COM before using DDT to make the following changes. A>ddt movcpm.com DDT VERS 2.2 NEXT PC 2700 0100 -l141b 141B MOV A,B 141C ORA A 141D JZ 09EF 1420 MOV A,M 1421 DCR B . . . -a141b 141B mvi a,8 141D jmp a07 1420 . -g0 A>save 38 movcpm1.com Use the new program MOVCPM1.COM in place of MOVCPM.COM. The RUBOUT and BACKSPACE key functions are identical in any CP/M system generated with MOVCPM1.COM. Licensed users are granted the right to include these modifications in CP/M V2.2 software. CP/M 2.2 Application Note 03, 06/25/81 Sample BIOS for a Serial Printer Device Copyright 1982 by Digital Research CP/M is a registered trademark of Digital Research. Compiled November 1982 Applicable products and version numbers: CP/M V1.4, V2.0, V2.1, and V2.2 Program: BIOS The following code fragment drives Diablo serial interface printers or other serial devices that use the X ON/X OFF protocol for synchronization. A device that uses this protocol receives data faster than it can print. The device transmits a CTRL-S character when its buffer becomes full, and a CTRL-Q to receive more data after the buffer is emptied. LIST$STAT EQU 00H LIST$DATA EQU 01H IN$MASK EQU 02H OUT$MASK EQU 01H LIST: CALL LISTST ! JZ LIST MOV A,C ! OUT LIST$DATA RET LISTST ;return list status (0 if not ready, FF if ready) LXI H,LST$FLAG IN LIST$STAT ! ANI INS$MASK ! JZ NO$INPUT IN LIST$DATA ! ANI 7FH ! CPI 'Q'-'@' ! JNZ S? MVI M OFFH S? CPI 'S'-'@' ! JNZ NO$INPUT MVI M,O NO$INPUT: IN LIST$STAT ! ANI OUT$MASK ! ANA M ! RZ ORI 255 RET LST$FLAG: DB 255 ;must be 255 initially Licensed users are granted the right to include these modifications in CP/M software. CP/M V2.2 Application Note 04, 2/20/82 BIOS Error Return Code Options Copyright 1982 by Digital Research CP/M is a registered trademark of Digital Trademark. DDT and SID are trademarks of Digital Research. Compiled November 1982 Applicable products and version numbers: CP/M V2.2 Program: BIOS Usually, CP/M responds only to a zero or nonzero value as the return code from the BIOS READ and WRITE entry points. If the value in register A is zero, CP/M assumes that the disk operation was completed successfully. If a nonzero value is in register A, the BDOS returns the message BDOS ERR ON x: BAD SECTOR. You then have the option of pressing the RETURN key to ignore the error, or CTRL-C to abort. This modification interjects three additional return codes for the BIOS READ and WRITE routines in register A as shown below. 0 The disk Read or Write operation was successful. 1 Bad Sector--indicates permanent disk error. 2 Select Error--indicates the drive is not ready. 3 R/O--the disk is Read-Only (used by WRITE). 4 File R/O--not normally used. In the following code segment, addresses given are hexadecimal offsets from the base of the CP/M system. The CCP is usually located at 980H, but can be located at A00H if you use a two-sector boot. After modifying your BIOS READ and WRITE routines to pass the extended error codes to the BDOS, you can assemble the BDOS patch for your size memory system. The cpmbase equals the BDOS entry point address at locations 6 and 7 in the base page of memory minus 806H. You must change this entry point address when you load DDT or SID . Under DDT or SID, follow the jump at location 5 until you find an address with a least significant digit of 6. In the following example, the cpmbase would be E506H-806H or DD00H. 0005 JMP CD00 CD00 JMP D3A4 D3A4 XTHL D3A5 SHLD E452 D3A8 XTHL D3A9 JMP E506 1 CP/M V2.2 Application Note 04 Patch into the SYSGEN or MOVCPM image exactly as you would patch in a new version of your BIOS, using the DDT i command followed by the DDT r command. Use the same offset as your custom BIOS. Before installing this patch, the code at the cpmbase + BBDh should read: lxi h,cpmbase +809H jmp cpmbase + B4AH Replace the preceding code with the following code: cpmbase equ ? ; ; org cpmbase + BBDH ; lxi h,cpmbase + 807H jmp cpmbase + 83AH end Or, you can install this change directly into MOVCPM, if MOVCPM.COM is on your system disk. The patch is installed in any size system that you build using MOVCPM. Make a back-up copy of MOVCPM.COM before using DDT to install the following procedure: A>ddt movcpm.com DDT VERS 2.2 NEXT PC 2700 0100 -l15bd 15BD LXI H,0809 15C0 JMP 0B4A 15C3 LHLD 15EA . . . -a15bd 15BD lxi h,807 15C0 jmp 83a 15C3 . -g0 A>save 38 movcpm1.com Use the new program MOVCPM1.COM in place of MOVCPM.COM. Additional error return codes for the BIOS READ and WRITE routines are supported in any CP/M system generated with MOVCPM1.COM. Licensed users are granted the right to include these modifications in CP/M V2.2 software. 2 CP/M V2.2 Application Note 05, 2/20/82 Improving the CTRL-S Function Copyright 1982 by Digital Research CP/M is a registered trademark of Digital Research. DDT and SID are trademarks of Digital Research. Compiled November 1982 Applicable products and version numbers: CP/M V2.2 Program: BDOS The CTRL-S function controls screen scrolling during CRT output. However, the system does not recognize CTRL-S if you type another character before it. In the following code segment procedures, addresses given are hexadecimal offsets from the base of the CP/M system. The CCP is usually located at 980H, but can be located at A00H if a two-sector boot is used. You can assemble the patch for your size memory system. The cpmbase equals the BDOS entry point address at locations 6 and 7 in the base page of memory minus 806H. You must change this entry point address when you load DDT or SID . Under DDT or SID, follow the jump at location 5 until you find an address with a least significant digit of 6. In the following example, the cpmbase is E506H-806H or DD00H. 0005 JMP CD00 CD00 JMP D3A4 D3A4 XTHL D3A5 SHLD E452 D3A8 XTHL D3A9 JMP E506 Patch into the SYSGEN or MOVCPM image exactly as you would patch in a new version of your BIOS, using the DDT i command followed by the DDT r command. Use the same offset as your custom BIOS. The call at cpmbase + 950H should be cpmbase + 923H before installing the following code: cpmbase equ ? ; ; org cpmbase + 950h ; call cpmbase + 92Ah end 1 CP/M V2.2 Application Note 05 Or, you can install the above procedure directly into MOVCPM, if MOVCPM.COM is on your system disk. The patch is applied automatically to any size system that you build using MOVCPM. Make a back-up copy of MOVCPM.COM before using DDT to make the following changes: A>ddt movcpm.com DDT VERS 2.2 NEXT PC 2700 0100 -l1350 1350 CALL 0923 1353 POP B 1354 PUSH B . . . -a1350 1350 call 92a 1353 . -g0 A>save 38 movcpm1.com Use the new program MOVCPM1.COM in place of MOVCPM.COM. Any CP/M system generated with MOVCPM1.COM has the improved CTRL-S function. Licensed users are granted the right to include these modifications in CP/M V2.2 software. 2 CP/M V2.2 Application Note 06, 2/20/82 Changing the Lines Per Page Copyright 1982 by Digital Research CP/M is a registered trademark of Digital Research. DDT is a trademark of Digital Research. Compiled November 1982 Applicable products and version numbers: CP/M V2.2 and V2.2 4200H Program: ED.COM This modification changes the number of lines scrolled by the P command in ED.COM from 23 to 14. Add 4200H to each address shown below for 4200H-based systems. Make a back-up copy of ED.COM before you use DDT to make the following changes: A>ddt ed.com DDT VERS 2.2 NEXT PC 1B00 0100 -l17da 17DA LXI H,0017 17DD SHLD 1D1C 17E0 RET . . . -s17db 17DB 17 e 17DC 00 . -^C A>save 26 ed.com Licensed users are granted the right to include these modifications in CP/M V2.2 and V2.2 4200H software. 1 CP/M V2.2 Application Note 07, 2/20/82 Changing the Restart Number in DDT Copyright 1982 by Digital Research CP/M is a registered trademark of Digital Research. DDT is a trademark of Digital Research. Compiled November 1982 Applicable products and version numbers: CP/M V1.4, V2.0, V2.1, and V2.2 Program: DDT.COM DDT uses RST 7 (machine instruction 0FFH) to set break points. To change the restart number, modify the three bytes indicated by ?? in the following procedure for a new restart instruction and location. The restart instruction uses the bit pattern 11XXX111, where XXX is the restart number you use. (AFH is RST 1, B7H is RST 2, and BFH is RST 3.) The restart location is usually the restart number times 8. Do not use RST 0 because it is reserved for CP/M. The following procedure applies to DDT supplied with CP/M V2.1 and V2.2. For V1.4 and V2.0, change the instructions at 19B and 19E to the following: 019B sta fe4 019E sta 10ee Make a back-up copy of DDT.COM before you use DDT to make the following changes: A>ddt ddt.com DDT VERS 2.2 NEXT PC 1400 0100 -l103 103 JMP 013D . . . -a103 0103 jmp 18b -a18b 018B lhld 1ec 018E shld 8e7 0191 inx h 0192 shld 8ed 0195 lda 1eb 0198 sta ad5 1 CP/M V2.2 Application Note 07 019B sta fea 019E sta 10f4 01A1 jmp 13d - s1ec 01EB ?? f7 01EC ?? 30 01ED ?? 00 01EE ?? . -g0 A>save 19 ddt6.com To change the restart number for DDT in the future, modify only the 3 bytes 1EBH, 1ECH and 1EDH. Licensed users are granted the right to include these modifications in CP/M software. 2 CP/M V2.2 Application Note 08, 2/20/82 Nested SUBMIT Files Copyright 1982 by Digital Research CP/M is a registered trademark of Digital Research. DDT is a trademark of Digital Research. Compiled November 1982 Applicable products and version numbers: CP/M V2.1 and V2.2 Program: SUBMIT.COM The CP/M SUBMIT program allows you to embed another SUBMIT command within a submit file. However, control does not return to the original SUBMIT file after executing the nested SUBMIT command. To return control to the original SUBMIT command, use any standard editor to type the following procedure into a file named SUBPATCH.ASM: ; ; subfcb: equ 5bbh bdos: equ 5 open: equ 211h ; org 22dh ;submit erase subroutine ; opsl: lda subfcb+15 ;file open ok if ext not full ral rnc lxi h,subfcb+12 ;try next extent inr m ops: lxi d,subfcb ;open extent jmp create ; org 25dh ;submit create subroutine create: call open inr a jnz opsl ;loop if open ok lxi d,subfcb mvi c,22 call bdos adi 1 ret ; ; the following code calls the above routines ; org 4feh ; call ops ;open the $$$.sub file jc 517h ;jump if not opened ok lda subfcb+15 ;set current record to end sta subfcb+32 jmp 51dh ;jump if open ok ; org subfcb db 1 ;force $$$.sub file to A: ; end Assemble SUBPATCH ASM to create the file SUBPATCH.HEX. Then use DDT to insert SUBPATCH.HEX into the SUBMIT.COM program, as shown below. A>ddt submit.com DDT VERS 2.2 NEXT PC 0600 0100 -isubpatch.hex -r -g0 A>save 5 submit1.com In the new program SUBMIT1.COM, control returns to the original SUBMIT file after the system executes embedded SUBMIT commands. Licensed users are granted the right to include these modifications in CP/M V2.1 and V2.2 software. CP/M V2.2 Application Note 09, 2/02/82 Configuring CP/M for Page Boundaries Copyright 1982 by Digital Research CP/M is a registered trademark of Digital Research. DDT is a trademark of Digital Research. Compiled November 1982 Applicable products and version numbers: CP/M V2.2 Program: MOVCPM.COM You can modify MOVCPM.COM to configure CP/M V2.2 for page boundaries (256 bytes) instead of kilobyte boundaries. Make a back-up copy of MOVCPM.COM before you use DDT to make the following changes. Save the changes in a new file named PGMOV.COM. The first argument designates the size of the system in pages that PGMOV is to construct. The first argument is optional, but must range between 64 and 255 (decimal) if used. A>ddt movcpm.com DDT VERS 2.2 NEXT PC 2700 0100 -l165 0165 CPI 10 0167 JC 0172 016A MVI L,00 016C MOV H,A 016D DAD H -s166 0166 10 40 0167 DA . -a16d 016D nop 016E nop 016F . -l1a2 01A2 ANI FC 01A4 MOV H,A 01A5 PUSH H 01A6 LHLD 0006 -ala2 01A2 ani fe 01A4 . -g0 A>save 38 pgmov.com Licensed users are granted the right to include these modifications in CP/M V2.2 software. CP/M V2.2 Application Note 10, BDOS, 03/12/82 Booting CP/M on Drives Other Than Drive A Copyright 1982 by Digital Research CP/M is a registered trademark of Digital Research. DDT is a trademark of Digital Research. Compiled November 1982 Applicable products and version numbers: CP/M V2.2 Module: BDOS Booting CP/M on a drive other than drive A changes the initial prompt displayed after a cold boot. Instead of A>, you must specify the drive intended to follow the cold boot in the following patch procedure. Also, your BIOS must pass the intended boot drive to register C in the CCP upon cold boots (see the CP/M Operating System Manual). The intended boot drive in this patch procedure and in your BIOS is indicated by a number relative to zero. (A=0, B=1, C=2, ..., P=15.) This procedure changes the drive selected by BDOS Function 13 (Reset Disk System). Use caution installing this patch because it requires modification to the CP/M submit processor (SUBMIT.COM). SUBMIT must write the $$$.SUB file to the boot drive you specify in this patch. The procedure to modify SUBMIT is described in CP/M V2.2, Patch 03, dated 1/21/82. Instead of setting the byte at 5BBH to 1, as described in Patch 03, set the byte to the specified boot drive plus 1. For example, if the boot drive is 1 (the B drive), then set the byte in SUBMIT.COM at 5BBH to 2. Place the following code in a file named CPMxx.COM (xx = memory size). Determine the CP/M base for your size memory and include it in the code. Assemble and insert CPMxx.COM into the SYSGEN or MOVCPM image exactly as you would patch in a new version of your BIOS. Use the DDT i command followed by the DDT r command. Use the same offset as your custom BIOS. Make a back-up copy of CPMxx.COM before you make the changes. cpmbase equ ? drive equ ? ;boot drive ;0=A, 1=B, ..., 15=P org cpmbase + 0148Ch jmp cpmbase + 15EEh ;was "xra a" org cpmbase + 15EEh mvi a,drive ;was "nop" sta cpmbase + 0B42h ;was "nop" jmp cpmbase + 1490h ;was "nop" Licensed users are granted the right to include these changes in CP/M V2.2 software. CP/M V2.2 Application Note 11 9/30/82 Chaining Programs Copyright 1982 by Digital Research CP/M and CP/NET are registered trademarks of Digital Research. MP/M II and PL/I-80 are trademarks of Digital Research. Compiled October 1982 Applicable products and version numbers: CP/M V2.2, CP/NET , and MP/M II . Program: CHAIN1.COM and CHAIN2.COM Menu-driven applications can be written to run under CP/M. If you develop applications using PL/I-80 , you can write the programs as a set of overlays. Often, the programs are written in assembly language, or require too much memory to make the overlay feature of PL/I-80 appropriate. Without using overlays, there are only two effective methods of chaining under CP/M V2.2. The first method uses the CP/M SUBMIT facility, in which the main menu program creates a SUBMIT file that lists the programs to be chained. The file must be written to drive A, and have the name $$$.SUB. The SUBMIT file consists of compatible lines, exactly like those you type at the console, following the system prompt. The commands are placed in reverse order, so the last command in the file is the first to be executed. Each command is placed in a 128- byte record with the following format: :n:C1:C2:...:cn:0:...: The first byte of the record contains the number of characters in the command (n), followed by the characters (c1-cn), and terminated with a zero. The number of characters in the command is written as a binary number and each character is represented in ASCII format. It does not matter what follows the terminating zero in the record. For example, if the command was STAT*.*, the first byte would be a binary 8, followed by the letters STAT*.* and terminated with a zero. The second method of program chaining is simpler. You include a procedure in the menu program that loads the next program and chains to it. Each program that might chain to another program must include a copy of the procedure. The procedure must first move itself out of the way so that it is not overwritten by the program it is loading. The example assembly language procedure is written to link with PL/I-80 modules as an external procedure. It can also be used in an assembly language menu program. To link to a PL/I-80 program, the following entry declaration must be included in the PL/I-80 program that does the chaining: dcl chain entry (char(12)); The character 12 variable consists of the standard CP/M File Control Block (FCB) format. The format can be created in the PL/I- 80 program as a structure. A char(12) variable can then be based at the same address as the structure for interfacing to the chain procedure. (See the following PL/I-80 program.) Note: the drive is not an ASCII character, but a binary number between 0 and 16, where 0 is the current default drive and 1 through 16 represent the CP/M drives A through P, respectively. chain 1: proc options(main); /* chain subroutine tester */ dcl 1 fcb static 2 drive fixed(7) init(0), 2 name char(8) init('CHAIN2'); 2 type char(3) init('COM'), dummy char(12) based(db), dp pointer, chain entry(char(12)); put skip list('Chain Text program 1'); dp = addr(fcb); call chain(dummy); put skip(2) list('Shouldn''t be here!!); end chain 1; This program prints the message Chain Test program 1, and chains to the program CHAIN2.COM on the default drive. CHAIN2 is a program identical to CHAIN1, except that it prints Chain Test Program 2 and chains to CHAIN1.COM. CHAIN1 and CHAIN2 then continue to chain back and forth to each other. Note: any statements following the call to the chain procedure are not executed because the chain procedure never returns. The chain procedure consists of two routines. An initialization routine initializes the FCB for the program to be loaded. Then, the initialization routine relocates the loader and FCB to the very top of the Transient Program Area (TPA), immediately below the BDOS, so it will not be overwritten by the loaded program. The loader begins at the label, code:, and ends at the end of the FCB, at the statement, codelen equ $-code. The loader routine sets the DMA address, reads a sector, checks for an end-of-file, increments the DMA addresses by 128 bytes, and repeats the process. When the end-of-file is detected, it jumps to the chained program. The code is as follows: public chain char(12) extrn ?signal ,/* loads another COM file, and executes it */ bdos equ 5 openf equ 15 readf equ 20 dmaf equ 26 cseq chain. mov e,m ! inx h ! mov d, m ! xchg ;get first arg address lxi d, fcb ! mvi c, 12 ! call move ;move string to FCB lxi d, fcb+12 ! mvi a, 0 ! mvi c, 21 call fill ;zero rest of FCB lhld bdos+1 ! lxi b, -code$len dad b ;make space at ;top of TPA shld jmpr + 1 ;jump address push h ;save code address ;for RET xchg ! lxi h, fcb-code ! dad d ;make address of FCB shld FCBR+1 ;and fix LXI push h ;save FCB ;destination address lxi h, code ! mvi c, code$len call move ;dest in DE pop d ;recover address of FCB mvi c, openf ! call BDOS ;open file inr a ! jz sig ;if any error, ;signal error pop h ! sphl ! push h ;point stack to top ;of TPA ;and save code addr lxi h, 100h ;point to start of ;TPA ret ;to loader "code" code: push h ! xchg ! mvi c, dmaf call BDOS ;set the DMA address FCBR lxi d, $-$ ! mvi c, readf ! call BDOS ;read the next record ora a ! jnz 100h ;EOF -| start TPA pop h ! lxi d, 128 ! dad D ;recover and bump DMA jmpr jmp $-$ ;jump to code FCB: ds 1 ;drive code CP/M V2.2 Application Note 11 ds 8 ;filename ds 3 ;filetype ds 4 ;control info ds 16 ;disk map ds 1 ;rrec codelen equ $-code move: ;c = # bytes, hi = source, de = desti- nation mov a,m ! stax d inx h ! inx d ! dcr c jnz move ret fill: ;a = byte to fill, c = # bytes, de = start ad- dress stax d ! inx d dcr c ! jnz fill ret sig: lxi h, siglist ! call ?signal ! jmp 0;signal error siglist: ;(fixed(6), ;bit(8),ptr,ptr) dw sigcode, sigsub, sigfil, message sigcode db 6 ;undefined file ;error sigsub db 2 ;arbitrary subcode ;for id sigfil dw fpb ;ptr to file ;parameter block message dw quack ;auxiliary ;operator message fpb ;PL/I fuke ;oaraneter bkicj fcbptr dw FCB-1 ;fcb-1 fpblst dw 0 ;(unused)ptr column dw 0 ;current column ;fixed(15) curline dw 0 ;current line ;fixed(15) curpage dw 0 ;current page ;fixed(15) currec dw 0 ;(unused)fixed(15) lookchr db 0 ;look ahead char ;char(1) ioend dw 0 ;i/o end address iostk dw 0 ;user stack upon ;sio entry spacer ds 4 ;spacer linesz dw 0 ;line size ;fixed(15) pagesz dw 0 ;page size ;fixed(15) fixedsz dw 0 ;fixed size ;fixed(15) blocksz dw 0 ;block size ;fixed(15) filedes dw 0 ;block size ;fixed(15) dtitle db 0 ;default title ;char(14)varying quack db 17,'Bad Chain Attempt',0 ;error message Licensed users are granted the right to include these modifications in CP/M, CP/NET and MP/M II software. CP/M V2.2 Application Note 12, 11/1/82 Interpreting CTRL-Z in SUBMIT Files Copyright 1982 by Digital Research CP/M is a registered trademark of Digital Research. DDT is a trademark of Digital Research. Compiled November 1982 Applicable products and version numbers: CP/M V2.2 Program: SUBMIT.COM SUBMIT does not accept control characters in SUB files. SUBMIT recognizes certain control characters when preceded by an up arrow. SUBMIT should interpret the two characters ^z as CTRL-Z. Procedure: Make a back-up copy of SUBMIT.COM before you use DDT to make the following changes. A>ddt submit.com DDT V2.2 NEXT PC 0600 0100 -l0441 0441 SUI 61 0443 STA 0E7D 0446 MOV C,A 0447 MVI A,19 0449 CMP C 044A JNC 0456 044D LXI B,019D 0450 CALL 02A7 045 JMP 045E 0456 LDA 0E7D 0459 INR A -s442 0442 61 41 0443 32 . -g0 A>save 5 submit.com Licensed users are granted the right to include these changes in CP/M V2.2 software. CP/M V2.2 Application Note 13, 01/21/82 Exiting PIP When Using SUBMIT and XSUB Copyright 1982 by Digital Research CP/M is a registered trademark of Digital Research. DDT is a trademark of Digital Research. Compiled November 1982 Applicable products and version numbers: CP/M V2.2 Program: PIP.COM When using the SUBMIT and XSUB utilities to execute multiple PIP commands from a SUBMIT file, it is not possible to exit from PIP automatically. The SUBMIT utility does not accept lines with only a carriage return. This application note patch modifies PIP so a period can be used to exit from PIP instead of a carriage return. In the submit file, place a single period (.) on a line by itself after the last PIP command to be executed. Procedure: Make a back-up copy of PIP.COM before you make any changes. The program DDT is required to make the changes. Use the following sequence of commands. 0A>ddt pip.com DDT VERS 2.2 NEXT PC 1E00 0100 -l54f 054F CPI 00 0551 JNZ 055E 0554 LHLD 1DFC . . . -a54f 054F cpi 2 0551 jnc 55e 0554 . -g0 A>save 29 pip.com Licensed users are granted the right to include these changes in CP/M 2.2 software. CP/M V2.2 Application Note 14, 8/11/82 Turning CTRL-P On and Off from within a CP/M V2.2 SUBMIT File Copyright 1982 by Digital Research CP/M is a registered trademark of Digital Research. Compiled November 1982 Applicable products and version numbers: CP/M V2.2 You can use the SUBMIT facility for batching job streams to turn the CTRL-P toggle on and off from within that SUBMIT file. Although there is a patch to SUBMIT that forces it to accept control characters when preceded by an up-arrow, ^, SUBMIT does not act on a CTRL-C nor a CTRL-P. The assembly-language program which follows turns CTRL-P on or off from within a SUBMIT file. The same assembly code can be used from within an applications program to turn CTRL-P on and off. This program must be executed before XSUB, if XSUB is to be active in the SUBMIT file. Although the CP/M V2.2 Operating System Manual states, "The XSUB command is included as the first line of your submit file...," this is not necessary. XSUB can be activated and deactivated within a SUBMIT file. An assembly-language program is listed that deactivates XSUB and also turns off CTRL-P if it is on. Use this program from within a SUBMIT file to turn the ^P toggle on and off. This program can also be invoked from the console. If the CTRL-P toggle is off, this program turns it on; if on, the program turns it off. It issues an appropriate message to the console that is also echoed on the list device. The program calculates the location of the ^P toggle in the BDOS by getting the BDOS address from the jump instruction located at 0005h in page zero and adding 307h to that address. It then does an exclusive on of the toggle byte to turn ^P on or off. Note: if XSUB is to be active in the submit file, ^P must be turned on before executing XSUB. To turn off ^P in a submit file in which XSUB is active, execute a program that deactivates XSUB, such as the DEXSUB program which is listed following this program. CntlP: org 100h ;start of TPA bdos equ 5h ;BDOS jump instruction bdosa equ bdos+1 ;BDOS entry address pstr equ 9 ;print string function testoff equ 2feh ;offset for verification listcp equ 0dh ;^P offset in page mvic equ 3eh ;MVI C,x instruction cr equ 0dh ;carriage return lf equ 0ah ;line feed lhld bdosa ;pick up address of BDOS in HL lxi d,testoff ;offset of ^P page in DE for add dad d ;HL= compare area in BDOS lxi d,string ;DE= compare string compare: ldax d ;is character a 0? ora a ; jz ok ;yes, we're done cmp m ;is BDOS same as string? inx h ;next byte inx d ; jz compare ;BDOS = string keep looping error: mvi c,pstr ;else print error message lxi d,errormsg ; jmp bdos ;return to CCP from BDOS ok: mvi l,listcp ;listcp page offset mvi a,1 ;toggle ^P byte on or off sub m ;true = 1, false = 0 mov m,a ;put results back in memory cpi 0h ;see if on or off jz othermsg ;to issue appropriate message lxi d,onmsg ;^P turned on jmp print ;go around othermsg: lxi d,offmsg ;^P turned off print mvi c,pstr ;print sign-on message jmp bdos ;return to CCP from BDOS onmsg: db cr,lf,'(^P turned on)$' offmsg db cr,lf,'(^P turned off)$' errormsg: db cr,lf,'Unable to find BDOS$' string db ret,mvic,1,jmp,0 end Dexsub: org 100h ;start of TPA bdos equ 0005h ;bdos location in base page mvi c,9 ;print string = function 9 lxi d,msg ; call bdos ; mvi c,0 ;system reset = function 0 jmp bdos ;exit bdos to ccp msg db 0dh,0ah,'(xsub deactivated; ^P turned off if on)$' end This application was developed and tested by Digital Research Technical Support using standard Digital Research products. Modifications required to assemble, compile, or execute under non- standard or non-Digital Research products are the responsibility of the user. Digital Research specifically disclaims any express or implied warranty and shall not be liable for any loss of profits, loss of business, loss of use or of data, interruption of business, nor for indirect, special, incidental, or consequential damages of any kind caused by the use or adaptation of this application note. Licensed users are granted the right to include these changes in CP/M software. CP/M V2.2 Aplication Note 15, 12/22/82 Debugging a CP/M V2.2 BIOS Copyright 1982, 1983 by Digital Research CP/M is a registered trademark of Digital Research. DDT, MAC, and SID are trademarks of Digital Research. Compiled February 1983 You can easily customize the CP/M V2.2 operating system for a particular machine if you use the following steps when it is necessary to debug a BIOS. You must have a system running under CP/M with a minimum of 48K to implement this scheme. CP/M V1.4 is all right, and the system need work only well enough to load DDT or SID . (SID is preferable and should be used if available.) 1) Carefully do a thorough code walk-through. This should take about eight hours. Pay particular attention to the Disk Parameter Blocks and Disk Parameter Headers, especially if you hand-coded these items to assemble your BIOS instead of using the DISKDEF.LIB and MAC . A slight miscalculation in a DPB or DPH can cause a BIOS to perform most functions correctly but fails under obscure circumstances; or, BIOS performs one function properly and fails to perform all others. 2) Using your old CP/M system, create your new system and configure it to 20K. Ensure that the old system does not use location 38H, which is DDT's Restart7 location. 3) Load the new 20K system underneath DDT in the old 48K system's TPA with the command DDT CPM20.COM. Figure 1-1 illustrates this scheme. 48K BIOS 48K BDOS DDT or SID 4A00 20K BIOS 3C06 20K BDOS 3400 20K CCP 980 900 BOOT SYSGEN or MOVCPM 100 BASE PAGE Figure 1-1. Loading Your New System 1 CP/M V2.2 Application Note 15 4) At location 980 (A00h in some systems), you should find the base of the CCP, recognized by two jumps followed by the copyright message. Move the 20K system into its correct W memory location using the DDT M (move) command. If DDT lists a next address of 2300, then this command is M980,2300,3400. 5) In the 20K BIOS jump vector at 4A00h, insert breakpoints with Restart7s, or, if you are using SID, insert passpoints. This should be restricted to the disk entry points unless you have a problem with console I/O. If the problem occurs only under certain conditions, place a RST7 initially only at the write entry point. When the conditions under which the problem occurs have been established, use a SAVE 1 xxx to return to the debugger you are using and to set additional breakpoints. 6) Run the 20K CP/M under the 48K CP/M's DDT. Issue the DDT command G4A00, which executes the new BIOS cold boot entry point. The cold boot initializes the base page for the 20K system and jumps to the CCP, which performs a BDOS Function 13 disk reset. The disk reset reads the directory sectors until it encounters a sector containing 0E5h in every byte. 7) If the problem you experienced fails to reappear when you begin single-cycling, it might have been a timing problem. If not timing then it is a logic or coding error, and you must continue to single-cycle the machine, examining the contents of registers and memory locations as you go. Pay particular attention to the following parameters: Track, Sector, Dmaad, Diskno, and the contents of Dirbuf. If you are using blocking/deblocking, also observe the contents of Sekdsk, Hstdsk, Sektrk, Hsttrk, Rsflag, Erflag, and the contents of the host buffer(s). Licensed users are granted the right to include these changes in CP/M software. 2