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ID Category [?] Severity [?] Reproducibility Date Submitted Last Update
08464 Core Critical (emulation) Always Oct 23, 2022, 04:47 Oct 25, 2022, 14:43
Tester pnp2084 View Status Public Platform MAME (Official Binary)
Assigned To pnp2084 Resolution Fixed OS Windows 10/11 (64-bit)
Status [?] Resolved Driver
Version 0.248 Fixed in Version 0.250 Build 64-bit
Fixed in Git Commit 99b3304 Github Pull Request # #10464
Summary 08464: trs80l2: Game boot loader fails due to overlapping FDC commands
Description The two attached graphic adventures have a custom boot loader which does not work on the TRS-80 Model I emulation. The games fail to start.
(It does work for the Model 3 emulation but that different boot code)
Steps To Reproduce Try to boot any of the two games. DISK ERROR will appear instead of a splash screen.
mame trs80l2 -flop1 spook_house.mfi
mame trs80l2 -flop1 sledge.mfi
Additional Information The ROM boot loader immediately jumps to $4200 but the read sector command is not finished.
The boot sector code issues a step command. The FDC emulation accepts the command (with a delay) and sets the busy bit. But when the previous read command finishes, BSY is cleared before the delayed step command starts.
As a result, the boot code sees the STEP command finish, putting the boot code in an inconsistent state.
Github Commit
Regression Version
Affected Sets / Systems trs80l2
Attached Files
zip file icon (112,253 bytes) Oct 23, 2022, 04:47 Uploaded by pnp2084
MFI disk images for Sledge of Rahmul and Spook House
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Oct 23, 2022, 05:27
I've created a pull request with a proposed fix: