seppdroid/Digital-Research-Source-Code
1
0
Fork 0
mirror of https://github.com/SEPPDROID/Digital-Research-Source-Code.git synced 2025-10-24 17:04:19 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

Upload

Browse Source 
Digital Research
This commit is contained in:
Sepp J Morris
2020-11-06 18:50:37 +01:00
parent 621ed8ccaf
commit 31738079c4
8481 changed files with 1888323 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

109
CPM OPERATING SYSTEMS/CPM 2.X/CPM 2.2/PATCHES/CPM22APN.04 Normal file
View File

@@ -0,0 +1,109 @@
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.