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ID Category [?] Severity [?] Reproducibility Date Submitted Last Update
08435 Core Critical (emulation) Always Oct 15, 2022, 17:10 Oct 23, 2022, 09:20
Tester pnp2084 View Status Public Platform MAME (Official Binary)
Assigned To galibert Resolution Fixed OS Windows 10/11 (64-bit)
Status [?] Resolved Driver
Version 0.248 Fixed in Version 0.249 Build 64-bit
Fixed in Git Commit 48eee89 Github Pull Request #
Summary 08435: trs80l2: WD1771 does not support a1 DAM status bit
Description The attached zork25.mfi will not boot on trs80l2 because the WD1771 emulation doesn't support the "a1" DAM marker bit.
Steps To Reproduce Run the trs80l2 driver with the floppy enabled:
mame -w trs80l2 -flop1 zork25.mfi
The disk will spin but no boot screen will appear.
The DMK file source for the MFI will boot in trs80gp.
Additional Information The problem is in wd_fdc.cpp. It is also a problem on write sector but this file won't test that.
For the WD1771 chip the status check needs to look at fb,fa,f9,fa and set an additional status flag.
Current code:

if((cur_live.data_reg & 0xfe) == 0xf8)
status |= S_DDM;

The WD1771 data sheets describe the proper behaviour fairly clearly:

a1a0 mark
 0 0 FB
 0 1 FA
 1 0 F9
 1 1 F8
Github Commit
Regression Version
Affected Sets / Systems trs80l2
Attached Files
zip file icon (256,105 bytes) Oct 15, 2022, 17:10 Uploaded by pnp2084
Zork aventure game in MFI forwmat
There are no relationship linked to this issue.
User avatar
Oct 17, 2022, 17:31
galibert has fixed the problem with these two commits:
User avatar
Senior Tester
Oct 17, 2022, 23:04
Thanks for the feedback.