06708: tandy2k: Does not boot from disk (regression)

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
06708	Media Support	Major	Always	Oct 12, 2017, 02:52	Oct 15, 2017, 19:07

Tester	Justin Kerk	View Status	Public	Platform	MAME (Official Binary)
Assigned To	crazyc	Resolution	Fixed	OS	Windows Vista/7/8 (64-bit)
Status [?]	Resolved			Driver	trs/tandy2k.cpp
Version	0.190	Fixed in Version	0.191	Build	64-bit
		Fixed in Git Commit		Github Pull Request #

Summary	06708: tandy2k: Does not boot from disk (regression)
Description	The tandy2k driver no longer boots from disk, it appears to wait forever at the BIOS memory = 128K screen.
Steps To Reproduce	> mame tandy2k msdos211 After waiting for a little while, it is supposed to boot to a DOS date/time prompt, but does not.
Additional Information	Works in 0.181, fails in 0.183, 0.190, and current git master.
Github Commit

Flags
Regression Version	0.182
Affected Sets / Systems	tandy2k

Attached Files

No.14268 crazyc Developer Oct 12, 2017, 20:35 edited on: Oct 12, 2017, 20:36	https://github.com/mamedev/mame/commit/e867481847a5d1659d142c9a01892cd5a695b6c8#diff-88ecf80cc7fbd274ae9cd653175ecc06 The stp_w part was commented later but the get_next_transition part causes this. The changed behavior starts at 0xfea38.
No.14279 demotester Tester Oct 15, 2017, 15:03 edited on: Oct 15, 2017, 15:04	Same apply for pcjr - refuse to run dos21 after 0.181! Warning: The problem appears to be global!
No.14282 crazyc Developer Oct 15, 2017, 19:07	Yup, commenting it out does fix the pcjr too so I've done that to solve it until it can be properly investigated.