08767: ct486: Emulated system locks up when attempting to boot MS-DOS 6.22 Setup Disk

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
08767	Crash/Freeze	Critical (emulation)	Always	Sep 21, 2023, 02:18	Sep 21, 2023, 10:23

Tester	Davidian1024	View Status	Public	Platform	MAME (Self-compiled)
Assigned To		Resolution	Open	OS	Linux (64-bit)
Status [?]	Acknowledged			Driver	pc/ct486.cpp
Version	0.258	Fixed in Version		Build	64-bit
		Fixed in Git Commit		Github Pull Request #

Summary	08767: ct486: Emulated system locks up when attempting to boot MS-DOS 6.22 Setup Disk
Description	When booting into the MS-DOS 6.22 disk 1, the system hangs at the moment when the setup program would normally first appear.
Steps To Reproduce	Boot the ct486 driver and configure a single 1.44MB floppy drive. Configure flop1 with MS-DOS 6.22 Disk 1 [rom name="disk1a.img" size="1474560" crc="69d8cfdd" sha1="30b4b2e99b26b0e5e7dbe61b9892e45fe751a3e8"] Boot the system again with this configuration and don't press any keys. Observe that the Starting MS-DOS... message appears and that floppy drive activity can be heard, but once floppy drive activity stops, the initial setup program screen never appears. The cursor only continues to blink as it had been, but nothing else on screen changes.
Additional Information	When booting off of the MS-DOS 6.22 Setup Disk from floppy drive A: the emulated system will hang just a moment or two after displaying the Starting MS-DOS... boot message. The boot up involves the usual startup through BIOS, including memory test and emulated floppy drive loading sounds. Pressing ctrl+alt+delete will not cause the system to reboot once the hang has occurred. It works before the hang occurs. You can tell when the hang has occurred once the floppy drive sounds have stopped. The cursor will continue to blink onscreen and the floppy can still be heard steadily whirring. This was reported previously here: https://mametesters.org/view.php?id=5547 Clearing the NVRAM makes no difference. I have the system configured with a single 1.44MB floppy as drive A: No hard drive. Beyond the F8 workaround mentioned in the previous report, I've noticed that repeatedly pressing any key starting just before the Starting MS-DOS... boot message appears seems to prevent the hang. The system manages to load the setup program if you do this.
Github Commit

Flags
Regression Version
Affected Sets / Systems	ct486

Attached Files