fdisk.exe fails to run on 8086

• Reporter: bttr
• Owner: mateuszviste
• Type: Bugs
• Status: Closed
• Component: packages
• MileStone: (None)
• Priority: 5 - Medium
• Severity: 5 - Medium
• Resolution: Fixed
• File: None

Details Reply

pce-ibmpc logs "undefined operation [C1 e1]", when FDISK is executed like "fdisk /?".

It runs fine, when I change emulated CPU to 80186.

After running "upx -d fdisk.exe", "fdisk /?" gives me "Abnormal program termination" and "Null point}r assignment" on the (emulated) 8086. (Yes, with } instead of an "e".)

At the same time pce-ibmpc logs:

3317:0D0A: undefined operation [C8 02]
3317:0D10: undefined operation [6A 05]
3317:0CE8: undefined operation [6A 24]
3317:0CF6: undefined operation [68 c7]
3317:0D01: undefined operation [68 d0]
...

I guess, we need to rebuild FDISK.EXE before using UPX --8086 and updating the package, but maybe I can find a working binary elsewhere.

Ticket History (3/11 Histories)

2022-01-31 02:17 Updated by: bttr

• New Ticket "fdisk.exe fails to run on 8086" created

2022-01-31 02:30 Updated by: bttr

Comment Reply

"undefined operation" will go away on the de-UPXed fdisk.exe, when using a 80186 CPU. -> Wrong compile-time options were used.

2022-01-31 03:25 Updated by: bttr

Comment Reply

I created an 8086-compatible FDISK.EXE based on Tom Ehlert's http://www.drivesnapshot.de/freedos/fdisk134.zip (also mirrored at https://www.ibiblio.org/pub/micro/pc-stuff/freedos/files/dos/fdisk/1.3.4/).

I removed the "-1" from CFLAGS at SOURCE\FDISK\MAKEFILE. Then I ran "upx --best --8086 FDISK.EXE -oFDISKUPX.EXE".

Both EXE file started fine on the emulated 8086. I also tried "--lzma", but (as expected) it starts quite slow on such a low-end CPU.

You can grab just FDISK.EXE and FDISKUPX.EXE from http://www.bttr-software.de/tmp/fdisk134_8086.zip

2022-01-31 03:27 Updated by: bttr

• Owner Update from (None) to mateuszviste

2022-01-31 04:09 Updated by: bttr

Comment Reply

I also reported this at https://github.com/FDOS/fdisk/issues/13 and https://gitlab.com/FreeDOS/base/fdisk/-/issues/5

(Edited, 2022-01-31 04:14 Updated by: bttr)

2022-01-31 19:20 Updated by: mateuszviste

• Status Update from Open to Closed

Comment Reply

Package updated using your new upx binary. Thank you!

2022-02-01 04:42 Updated by: bttr

Comment Reply

Thanks. :-)

But doesn't seem to be part of the updated image (31 Jan 2022).

Did a fresh install, but FDISK.EXE is still dated 3-18-2021.

2022-02-01 04:42 Updated by: bttr

• Status Update from Closed to Open

2022-02-01 04:48 Updated by: mateuszviste

Comment Reply

probably hadn't pushed the new ISO to website, I don't do it every time anything changes. did it now.

2022-02-01 05:03 Updated by: bttr

• Status Update from Open to Closed
• Resolution Update from None to Fixed

Comment Reply

Works as expected now with the updated ISO. :-)

2022-02-05 08:16 Updated by: bttr

• Component Update from (None) to packages