08850: DMK Disk format detection rejects single-sided DMK files

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
08850	Media Support	Major	Always	Apr 10, 2024, 01:39	Apr 10, 2024, 11:15

Tester	pnp2084	View Status	Public	Platform	MAME (Official Binary)
Assigned To		Resolution	Duplicate	OS	Windows 10/11 (64-bit)
Status [?]	Closed			Driver	trs/trs80.cpp
Version	0.264	Fixed in Version		Build	64-bit
		Fixed in Git Commit		Github Pull Request #

Summary	08850: DMK Disk format detection rejects single-sided DMK files
Description	MAME fails to identify single-sided DMK disk image files and rejects loading them.
Steps To Reproduce	Try to load a DMK file e.g. mame -w trs80m3 -flop1 TRSDOS13.dmk Results in: Fatal error: Device 5.25" double density floppy drive load failed: Unable to identify image file format
Additional Information	At least one problem: dmk_dsk.cpp checks for byte 4 to be zero but that byte contains flags (e.g. single-sided) The "i =4" below should be "i = 5" for (int i = 4; i < 0x10; i++) { if (header[i] != 0x00) return 0; } Introduced by wilbertpol in this commit: https://github.com/mamedev/mame/commit/699b8b5345061216c29e2ebdc5bb7e38350b048e There may be other problems but this is the most likely.
Github Commit

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Regression Version
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Attached Files

No.22051 pnp2084 Tester Apr 10, 2024, 01:41	Accidental duplicate, 8851 has the proper attachment.
No.22055 Robbbert Senior Tester Apr 10, 2024, 11:15	Duplicate of 8851.