Viewing Issue Advanced Details
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
Version 0.209 Fixed in Version 0.231 Build
Fixed in Git Commit c6c0f2f Github Pull Request #
Summary MESS-specific 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
Regression Version
Affected Sets / Systems trs80m4
Attached Files
There are no relationship linked to this issue.
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Senior Tester
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.
User avatar
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.
User avatar
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?
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Senior Tester
Apr 3, 2021, 18:19
Please note that booting of TRSDOS 6 will work, but it will only accept years 80 to 87.
User avatar
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?
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Senior Tester
Sep 2, 2021, 03:55
edited on: Sep 2, 2021, 08:40
They all work since April 3.