The Strange case of a Victor HC-95(a) 512KB!

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Par retrocanada76

Hero (538)

Portrait de retrocanada76

07-06-2022, 16:40

looks like a small change on the bios is needed though: http://www.zilog.com/docs/z180/appnotes/hd64180-migration.pdf

Par retrocanada76

Hero (538)

Portrait de retrocanada76

07-06-2022, 17:40

hmm i am confuse, says the default operation is hd64180 so I don't need to change the OCMR at all:

"To operate like the HD64180, write the Operation Mode Control Register (OMCR)
with either a 111XXXXX binary or FF hexadecimal value (the default value at
reset). To satisfy the Z80 peripheral (PIO, SIO, or CTC) requirements, however,
the user must modify this programming of the Operation Mode Control Register
(OMCR) to reflect either a 000XXXXX binary or 0F hexadecimal."

Par sdsnatcher73

Prophet (3677)

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07-06-2022, 20:33

It is interchangeable. No modification needed to the BIOS. But what would be the benefit to do this?

Par sdsnatcher73

Prophet (3677)

Portrait de sdsnatcher73

07-06-2022, 20:43

sdsnatcher73 wrote:
lintweaker wrote:

If I remeber correctly, Nextor uses some undocumented instructions like IXh IYl etc. The Z180 does not support these.
Thats way Nextor does not work.

That is too bad, software like Nextor should try to be compatible imho. Maybe a patch could be made?

I checked and the Nextor code itself uses all macros for the instructions that use ixl, ixh, iyl, iyh. The flashjacks and sunrise drivers don’t. If these would be changed to use the macros and the macros could check a compile time derivative to use Z180 compatible code (not sure if the assembler used has a cpu flag) it should be possible to create special builds.

Par retrocanada76

Hero (538)

Portrait de retrocanada76

07-06-2022, 21:01

Dunno, I need to check the user manual if there is any benefit. Btw my turbo roms are different than the ones widely shared in openMSX/blueMSX. I dumped them by pulling the ICs and reading them on the programmer. I will try using the official dump tool. But I have two 32k eprom chips named JVC024D with RS232/SETUP and DISK ROM on it and the other is named JVC024E which is the 32KB main BIOS modified. The extrom/kanji seems the same for both turbo non/turbo in the maskrom chips.

It is strange that this eprom chip carries the diskrom as it seems to be on the disk interface as well. Doesn't seem to be different.

Both my RS232/SETUP and the main bios are different from the ones posted. Maybe they are from another model ?

Par sdsnatcher73

Prophet (3677)

Portrait de sdsnatcher73

07-06-2022, 21:11

Send the dumps to tfh. Which model do you have? openMSX emulates the HC-95(A) so most likely the existing dumps come from that machine.

Par Manuel

Ascended (19059)

Portrait de Manuel

07-06-2022, 21:17

The EPROM dumps are the most valuable. I'd be very interested to receive them for studying purposes.

Par retrocanada76

Hero (538)

Portrait de retrocanada76

07-06-2022, 21:53

which email to send to ?

Par retrocanada76

Hero (538)

Portrait de retrocanada76

07-06-2022, 22:03

I could not read the masked roms. Either my eprom programmer wasn't enable to read them or I was using the wrong layout. I could only dump the two 27C256 eproms on it. The other ones seemed stock mask roms a TMM23128p and a TMM2356p:

Anyone knows which battery can I replace there ?

Par retrocanada76

Hero (538)

Portrait de retrocanada76

07-06-2022, 22:08

Also the openMSX roms have a kanjifont but I can't see any kanji rom in my board...

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