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- 2/20/86
-
- IBM PROVIDES THE FOLLOWING PATCH FOR DOS 3.0 AND DOS 3.1
- -------------------------------------------------------------------
-
- DESCRIPTION: This patch corrects a condition where DOS is doing a
- test on bit 8 to determine if an error code returned from INT 13h
- should fall into the DMA boundary violation handler. This test is
- causing error codes other than DMA (09h) to fall into this handler.
- The patch changes this test to a direct compare.
-
- The patch corrects the same problem with each version of DOS 3.
- ____________________________________________________________________
-
-
- The patch is made to the System file IBMBIO.COM.
-
- NOTE: The safest method of doing this is given in the last paragraph
- of this document. However, for those who feel sufficiently competant,
- and who don't wish to follow that course, the following method is
- presented.
-
- It will first be necessary to remove the Hidden/System/Read-only
- attribute, thus making the file a 'normal' file. AFTER you have
- completed the patch process, you MUST RESET this attribute to
- Hidden/System/Read-only.
-
- To work with the attibute, you can use the PD program CHMOD, or the
- Norton Utility Ver 3.1's FA.COM, Morgan Computing's DISKTOOL, or IBM's
- DISK REPAIR, a part of the PROFESSIONAL DEBUG package. You cannot use
- the DOS utility ATTRIB.COM.
-
- (Just for information, a 'normal' file attibute is either 00h or 20h,
- while a Hidden/System/Read-only attribute is either 07h or 27h. The
- attribute is one byte and is located in the Directory entry for the
- file, immediately following the last character in the filename
- extension. In this case, after the 'M' in COM.)
-
- See the documentation for whichever program above you've chosen to
- determine the procedure to be used.
-
- * * * * * * *
-
-
- NOTE: YOU ARE PATCHING THE HEART OF THE OPERATING SYSTEM... BE VERY
- CAREFUL!!! IF YOU THINK YOU MAY HAVE MADE A MISTAKE, EXIT
- BEFORE WRITING THE CHANGES AND START OVER AGAIN.
-
- Format a floppy using the command, FORMAT /S. Set the attribute for
- IBMBIO.COM to 'normal' as given above.
-
- Use the DOS utility DEBUG.COM, (or MicroSoft's SYMDEB), to make this
- patch. It is assumed that you are familiar with its use.
-
- Curiously, the patch changes only 4 bytes, though IBM indicates a
- 5-byte patch.
-
- -------------------------------------------------------------------
-
- PATCH NUMBER: PATCH31.001
-
- Use this patch if you have DOS 3.1:
-
- DOS LEVEL: 3.10
-
- FILE PATCHED: IBMBIO.COM
-
- OFFSET OF PATCH: 09BB (Note: DEBUG address = 0ABB)
-
- NUMBER OF BYTES: 5
-
- OLD CODE: F6 C4 08 75 0F
-
- NEW CODE: 80 FC 09 74 0F
-
-
- In what follows, Do not type the hyphens. The 'xxxx' mean 'don't care'.
- At the DOS prompt type:
-
- DEBUG d:\IBMBIO.COM <cr> where d: = drive containing IBMBIO.COM
- -D 0ABB L5 <cr>
- xxxx:0AB0 You should see OLD CODE given above starting at 0ABB.
-
- -E 0ABB 80 FC 09 74 0F <cr>
- -D 0ABB L5 <cr>
- xxxx:0AB0 You should see NEW CODE given above starting at 0ABB.
-
- -W <cr>
- Writing xxxx bytes
- -Q <cr>
-
- Patching complete. Reset the attribute to Hidden/System/Read-only.
- (At this point, you should consider bringing up the file again and
- and doing -D 0ABB L5, just as a final check).
-
- ----------------------------------------------------------------------
-
- PATCH NUMBER: PATCH30.001
-
- Use this patch if you have DOS 3.0
-
- DOS LEVEL: 3.00
-
- FILE PATCHED: IBMBIO.COM
-
- OFFSET OF PATCH: 0964 (Note: DEBUG address = 0A64)
-
- NUMBER OF BYTES: 5
-
- OLD CODE: F6 C4 08 75 04
-
- NEW CODE: 80 FC 09 74 04
-
- In what follows, Do not type the hyphens. The 'xxxx' mean 'don't care'.
- At the DOS prompt type:
-
- DEBUG d:\IBMBIO.COM <cr> where d: = drive containing IBMBIO.COM
- -D 0A64 L5 <cr>
- xxxx:0A60 You should see OLD CODE given above starting at 0A64.
-
- -E 0A64 80 FC 09 74 04 <cr>
- -D 0A64 L5 <cr>
- xxxx:0A60 You should see NEW CODE given above starting at 0A64.
-
- -W <cr>
- Writing xxxx bytes
- -Q <cr>
-
- Patching complete. Reset the attribute to Hidden/System/Read-only.
- (At this point, you should consider bringing up the file again and
- and doing -D 0A64 L5, just as a final check.)
-
- --------------------------------------------------------------------------
-
-
- TO UPDATE IBMBIO.COM ON YOUR HARD DISK:
-
- IMPORTANT!!! DO NOT USE DEBUG TO PATCH IBMBIO.COM ON A HARD DISK.
-
- 1. Complete the above, creating a floppy with the patched
- IBMBIO.COM, with attibute reset to Hid/Sys/Read-only. Then: Copy
- the DOS utility SYS.COM onto the floppy. Set the default drive to A:
- and put the floppy in it. Then type SYS C:<cr> (assuming your HD is
- Drive C:). You should then see the message 'system transferred'.
-
- YOU CANNOT SIMPLY USE DEBUG TO PATCH AN IBMBIO.COM THAT RESIDES ON A
- HARD DISK, BECAUSE DEBUG WILL NOT WRITE THE FILE BACK TO THE SAME
- SPACE ON A HARD DISK. IBMBIO.COM MUST RESIDE IN A SPECIFIC PLACE ON
- A DISK, and while DEBUG will write it back to the same place it came
- from on a floppy, it will not do so on a hard disk.
-
- * * * *
-
- If you're patching a hard disk and have a problem, you can always put
- your DOS System disk in Drive A:, boot it, and type SYS C:<cr>, which
- will replace the system files on the HD, provided of course that you
- haven't written anything to the hard disk before doing this.
-
- If you are not familiar with DEBUG, or simply don't want to monkey with
- it, then you may obtain the DOS 3 Patch Disk No. 1, from your dealer at
- no charge, (ask them to get it from Dealer Support if they don't have it).
- That disk contains an IBM program PATCH.COM, which will make the patch
- automatically. Since that program is not PD, we cannot post it.
-