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ID Category [?] Severity [?] Reproducibility Date Submitted Last Update
06340 DIP/Input Feature Always Aug 2, 2016, 12:26 Aug 3, 2016, 23:37
Tester demotester View Status Public Platform MESS (Unofficial Binary)
Assigned To Resolution Open OS Windows XP
Status [?] Acknowledged Driver
Version 0.176 Fixed in Version Build Normal
Summary MESS-specific 06340: mz80b, mz2000, mz2500: The Reset key is missing !
Description B-lines of Sharp MZ computers (i.e MZ-80B, MZ-2000, MZ-2500) have two type of reset keys: "Reset" and "IPL reset" !

The "IPL Reset" behave same to power off/on and there even exists a BASIC command "BOOT" that does the same.
The "Reset" is different; on MZ-80B and MZ-2000 it will return into MONITOR from the BASIC and on MZ-2500 into a BASIC prompt.

MESS/MAME emu already support two type of resets: "Hard Reset" and "Soft Reset" but on the MZ B-lines drivers both resets behave as "IPL Reset" !?
Proposal would be to change the "Soft Reset" to behave as "Reset" key ! (i.e. F3 key ="Reset", Shift+F3="IPL Reset")
Steps To Reproduce
Additional Information
Regression Version
Affected Sets / Systems mz80b, mz2000, mz2500
Attached Files
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User avatar
Aug 2, 2016, 19:06
According to the MZ-80B schematics, RESET and IPL RESET are not keys at all but switches on the back of the unit that are hooked up to the control bus. The functional difference between the two seems to be that RESET pulses the Z80 reset line but does not reset the PIO or the memory selector (IC2), both of which are triggered by BOOT RESET.

mz80b and mz2000 are marked MACHINE_NOT_WORKING anyway; the former is now wrongly configured like mz80k.
User avatar
Aug 2, 2016, 19:50
edited on: Aug 5, 2016, 11:07
Correct, but we can also call it Reset buttons. ;)

Yeah, currently the mz2000 is marked NOT_WORKING, but this does mean nothing as many of tested tapes work pretty good. (of course, that does not apply for those mentioned in the sw-list... many of these in sw-list are baddump anyway)

There is still a problem when loading a tape with several parts, you need to press F2 after each part to continue with loading, as the software tape controll seems is not emulated. But on the end, it works.
A few games have problem with keyboard; when ask in menu to press some key, it is not accepted.
And also the .mzt format seems broken in mz2000 driver, but .wav format works fine.
That would be all problems found in the driver, so only a little is missing to be a perfect.

Yeah, while the driver is capable to load tapes that starts from IPL, it is unable to LOAD / SAVE from the BASIC. So, the programs that starts from BASIC or MONITOR is currently not possible to run.
I guess the culprit for this is unemulated automatic tape control. For sure, if that were done, the driver could be declared as WORKING. But as things stand now, probably will not happen... too bad.

EDIT: Btw. there might be more drivers like spc1000/1500 affected with the same "Reset buttons" problem !

User avatar
Aug 3, 2016, 14:07
edited on: Aug 3, 2016, 14:13
I misread the specs slightly. The device that only gets reset upon a BOOT RESET is the 8255, not the PIO.

The 8255 itself can also trigger an IPL reset by setting bit 3 of its port C ($E2) to active low.