07308: trs80m4: The TRS-80 Model IV will not boot any Model IV disks, only Model III disks.

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
07308	Known Issues/To-Do's	Minor	Always	Apr 29, 2019, 01:58	Sep 2, 2021, 03:55

Tester	star2root	View Status	Public	Platform	MAME (Self-compiled)
Assigned To	Robbbert	Resolution	Fixed	OS
Status [?]	Resolved			Driver	trs/trs80m3.cpp
Version	0.209	Fixed in Version	0.231	Build
		Fixed in Git Commit	c6c0f2f	Github Pull Request #

Summary	07308: trs80m4: The TRS-80 Model IV will not boot any Model IV disks, only Model III disks.
Description	The TRS-80 Model III is actually working pretty well and is booting most DOS's in IMD format and seems to support double density disks. The TRS-80 Model IV boots the same disks as the model III, but I can't get it to load any model IV OS in any format, only Model III disks. This is apparently a known problem, as it is documented in the source code, but there is not bug open for it here that I could find.
Steps To Reproduce	Attempt to boot a TRS-80 Model IV OS disk in any format on the TRS-80 Model IV emulation.
Additional Information
Github Commit

Flags
Regression Version
Affected Sets / Systems	trs80m4

Attached Files

No.16394 Robbbert Moderator Apr 30, 2019, 10:56	When there's a note in the source you don't need a bug report here too. That's just wasteful duplication.
No.16396 Tafoid Administrator Apr 30, 2019, 14:54	At one time, Fujix and I (mostly Fujix) got a good 30-40% of source bugs placed on MT. But, after dozens of versions of releases and multiple times where a bug was fixed and the MT bug was not even handled/acknolwedged here by the developer fixing the bug or noted by anyone else - we decided to discontinue wholesale use of the KNOWN issues category. I don't mind it being used occassionally, esp on machines which have active developers.. Just don't make a habit of reporting known things plainly listed in source files. As Robbbert said, it can be wasteful for the time of everyone involved.
No.16425 star2root Viewer May 4, 2019, 21:13	Reporting it allows: Me and other people to be notified of progress, discussion, and when the issue is fixed. Gives us a place to discuss what might be causing the problem, and the feasibility of potential fixes. A mere note in the code does not accomplish that. I tend to track anything I post as well, and if I see it's been fixed I update my posting here on the issue. Any idea what the root cause of this issue is? Is it a disk format handling issue, or other missing functionality of the model 4 that causes it to fail to boot? Did it ever work or is this a regression?
No.18637 Robbbert Moderator Apr 3, 2021, 18:19	Please note that booting of TRSDOS 6 will work, but it will only accept years 80 to 87.
No.19199 star2root Viewer Sep 2, 2021, 00:03	I have tried TRSDOS6, LDOS, and a few other. None boot. Rapid DOS displays some text and hangs. Have there been any updates on this?
No.19207 Robbbert Moderator Sep 2, 2021, 03:55 edited on: Sep 2, 2021, 08:40	They all work since April 3.