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

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Par retrocanada76

Hero (538)

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04-06-2022, 19:34

the RGB is a db25 i don't know why they needed so many pins... is the external floppy toghether ?

Par sdsnatcher73

Prophet (3678)

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04-06-2022, 19:41

No the DB25 has same pinout as RGB21 connector (for pin 1 until 21, the rest is not connected). Possibly gdx mistook the keyboard connector to external floppy drive connector (they look similar). Or maybe some version exist that does have external floppy connector?

Par gdx

Enlighted (5849)

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05-06-2022, 02:40

sdsnatcher73 wrote:

Mitsubishi ML-G30 (and as such so does the Hitachi MB-H70) has external floppy unit even if it already has 2 internal drives.

You are right. I confused with the keyboard connector. The Victor HC-90/95 does not have a floppy drive connector at back. Only the Mitsubishi ML-G30 have one despite there being two locations inside.

gdx wrote:

HC-90/HC-95 looks a little too dull but it's a great MSX2. The only thing I don't like much is the RAM not locating in a 3-x slot. If I had one I'd try to swap the RAM slot with the Disk-ROM slot.

It's probably complicated to do this because of the accesses to the FDD registers via the addresses 7FF8h~7FFFh.

Par retrocanada76

Hero (538)

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05-06-2022, 04:55

probably it would be easier to make a slot converter for the JVC extend slot and use can put a mapper sitting on slot 2 alone. I guess the connector is this one but I need to make some measurements:

https://www.digikey.ca/en/products/detail/molex/0850421079/2...

Par gdx

Enlighted (5849)

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05-06-2022, 10:36

It's maybe possible just to build memory boards over 256kB. That would be a pretty effective solution although, in rare cases, the Bios mismanages slots when RAM less than 8000h is in a 0-x slot.

Alternatively, BMMS or the MSX-DOS2 also bypasses the problem that causes RAM in slot 0-x to prevent a RAM extension from being automatically selected as main RAM.

Par sdsnatcher73

Prophet (3678)

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05-06-2022, 11:20

retrocanada76 wrote:

probably it would be easier to make a slot converter for the JVC extend slot and use can put a mapper sitting on slot 2 alone. I guess the connector is this one but I need to make some measurements:

https://www.digikey.ca/en/products/detail/molex/0850421079/2421592

I think an angled connector will work better with a PCB:

https://www.digikey.ca/en/products/detail/harting/0903196692...

Par retrocanada76

Hero (538)

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06-06-2022, 00:52

I agree with the right angle but I couldn't find a female version :/

Par retrocanada76

Hero (538)

Portrait de retrocanada76

06-06-2022, 00:54

Par retrocanada76

Hero (538)

Portrait de retrocanada76

06-06-2022, 01:12

unfortunately Nextor fails with kernel error 6 when switching Z180.

Sofarun also does not run it exits instantly on z180. Does it really pay using undocumented instructions on these ?

Par gdx

Enlighted (5849)

Portrait de gdx

06-06-2022, 02:14

I remember seeing an excerpt from the documentation for the HC-90/95. It said that the Z80/Z180 switching should be done when the computer is off only. Then several people say that most games that do direct accesses do not work in Z180 mode. Panasonic did much better with the Turbo R.

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