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ID Category [?] Severity [?] Reproducibility Date Submitted Last Update
08511 Core Major Always Nov 10, 2022, 01:09 9 hours ago
Tester pnp2084 View Status Public Platform MAME (Official Binary)
Assigned To tlindner Resolution Fixed OS Windows 10/11 (64-bit)
Status [?] Resolved Driver
Version 0.249 Fixed in Version 0.254GIT Build 64-bit
Fixed in Git Commit 6ea69b0 Github Pull Request # #11041
Summary 08511: trs80l2: SuperUtility 3 boot fails because of false sync
Description The attached su3v30-perl.mfi (from the su3v30.dsk DMK file) fails to boot on the TRS-80 Model I.

The problem is the RADDR commands see false FM 0xFE sync bytes in the MFM data of Track 1.
As a result, the code retries the RADDR a few times until it fails.

The following breakpoints can be used to see the RADDR results.
bp 452d - $c0 RADDR
bp 452a - see 4a00 (HL) accumulate bogus results

The groups of 6 bytes at 0x4a00 are:
"FE FE FF F2 B1 F5" - false
"20 20 20 02 76 DE" - real
"30 30 30 02 2D 69" - real
"25 25 25 02 DE 9E" - real
"E5 EF F5 C6 DE 77" - false
"F3 F1 FE BE 5F 77" - false
Steps To Reproduce The follow command will display "DIsk Error _"
mame trs80l2 -flop1 su3v30-perl.mfi
Additional Information Possibly the WD17xx state machine should enforce some "sync zero" bits before detecting the FM IDAM.
Github Commit
Regression Version
Affected Sets / Systems trs80l2
Attached Files
zip file icon (293,565 bytes) Nov 10, 2022, 01:09 Uploaded by pnp2084
SuperUtility 3.0 for TRS-80 Model I
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30 days ago
Ok, I now know how the wd fdcs detect FM special marks, and the current code is incorrect. I'll try to work on a fix.