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ID Category [?] Severity [?] Reproducibility Date Submitted Last Update
08100 Media Support Major Always Oct 5, 2021, 15:35 Apr 30, 2022, 02:21
Tester cuavas View Status Public Platform MAME (Official Binary)
Assigned To Resolution Fixed OS
Status [?] Resolved Driver
Version 0.236 Fixed in Version 0.243 Build 64-bit
Fixed in Git Commit a7e49b6 Github Pull Request # #9625
Summary MESS-specific 08100: osborne1 and clones: IMD disk image support is broken
Description IMD disk images don’t work properly, giving read errors from CP/M BDOS. The osborne1 driver is just an example, this seems to affect lots of systems with floppy drives. This is possibly related to the code that’s supposed to support reading alternate tracks when a high-density floppy image is mounted in a drive with coarser head steps.
Steps To Reproduce Start osborne1 driver with a CP/M boot disk in the first drive and an IMD disk image in the second drive, using the default 5.25" SS DD drive option. The CP/M boot disk from the software list works.

mame osborne1 -flop1 cpm22 -flop2 amcalla

Hit return at the bootloader prompt, wait for the menu to appear

Hit escape and wait for the CP/M “A>” prompt to appear

Type B: and hit return

Watch the “Bdos Err On B: Bad Sector” error messages
Additional Information
Github Commit
Regression Version 0.228
Affected Sets / Systems osborne1 and clones
Attached Files
zip file icon (28,460 bytes) Oct 5, 2021, 15:35 Uploaded by cuavas
There are no relationship linked to this issue.
User avatar
Oct 5, 2021, 17:11
edited on: Oct 5, 2021, 17:12
Specific regression appears to be happening not on the initial IMD changes on January 9th, 2021, but sometime during January 10th, 2021 where a couple of follow up patches were made. Possible suspects:
User avatar
Apr 30, 2022, 02:20
This particular symptom seems to have been caused by using the image in a quad density drive.