Yamaha CX5M, CX5M II, CX7M

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By Wierzbowsky

Guardian (3431)

Wierzbowsky's picture

13-02-2016, 22:41

Pasi, I assumed you read my last post on that page, so I didn't send you this info in e-mail:

https://www.msx.org/forum/msx-talk/hardware/yamaha-cx5m-cx5m...

I was describing VRAM and RAM board installation on that Russian MSX1 board. Please review my post - it should help you to get the computer working with both boards.

By zPasi

Champion (499)

zPasi's picture

14-02-2016, 08:41

Alexey wrote:

Pasi, I assumed you read my last post on that page, so I didn't send you this info in e-mail:

Actually I did, good info, thanks! I wouldn't get this far without it.

The thing is, I don't have parts for your RAM mapper board yet. So I tested this with my external DIY mapper. And I haven't changed that BIOS yet, so there is the old BIOS still there. And that one doesn't initialise the mapper, right?

By Wierzbowsky

Guardian (3431)

Wierzbowsky's picture

14-02-2016, 11:32

You need to add 2 chips on the board so it could have proper signals for your mapper. The BIOS you must change, otherwise you won't be able to access more than 16kb of VRAM.

By zPasi

Champion (499)

zPasi's picture

14-02-2016, 12:10

Alexey wrote:

You need to add 2 chips on the board so it could have proper signals for your mapper.

When using your RAM board, yes. I see those chips combine addres decoding with IORQ, RD and WR signals to just two signals, MAPWR and MAPRD. But my external mapper doesn't need them. Because it's external Smile

My plan is to implement self-initialisation in my external mapper to verify this all works, and then build the internal version, and change the BIOS.

Quote:

The BIOS you must change, otherwise you won't be able to access more than 16kb of VRAM.

Actually, the 128K VRAM is already accessible, just not thru the BIOS. Don't worry, I'll change the BIOS, when it's the time Smile

I'm sure all your instructions are correct, but I like to experiment a little Smile

BTW: the motherboard I'm working on, is from this model I think. Note the keyboard: it is not "QWERTY", even in latin mode. Is it some old Russian standard?

By Wierzbowsky

Guardian (3431)

Wierzbowsky's picture

14-02-2016, 12:56

That traditional Russian typewriters all had "ЙЦУКЕНГ" keyboard layout. So someone decided not to use "QWERTY", but a phonetic layout that corresponds to "JCUKENG". I've seen that layout only on Russian MSXs produced in Japan. With the time you can get used to typing with this layout like you do with QWERTY. Wink

By pseen

Resident (60)

pseen's picture

12-04-2016, 12:04

By Grauw

Ascended (10604)

Grauw's picture

12-04-2016, 13:05

Nice, quite a comprehensive review!

Seems the review copy came with the Japanese YRM cartridges (with two-digit YMxx codes); I wonder if some of the remarks on Japan-isms got resolved in the international versions.

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