VRAM board for Yamaha CX5MII

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By o.geerdink

Hero (543)

o.geerdink's picture

30-06-2015, 08:20

I have a willem eprom burner and can code machinelanguage, maybe we can meet someday to expand our cxm5m/ii's with the memory and vram and scrum a working BIOS together.

By Jipe

Paragon (1366)

Jipe's picture

30-06-2015, 11:14

in my CX5MII mod MSX2 i have 8250 roms , Bios and Expand and work fine

By Grauw

Ascended (8513)

Grauw's picture

30-06-2015, 13:03

Jipe, did you have to change any of the wiring or could you just socket the new ROMs? And does the BIOS still work if you don’t add the RTC circuitry?

By Jipe

Paragon (1366)

Jipe's picture

30-06-2015, 13:43

see this PDF for instruction : http://msx.hansotten.com/uploads/msxdocs/yamahacx5m2msx2.pdf
title is false is for CX5MII (bug of HansO Wink )
i have add the RTC with spare of 8235 HS
-
but i see after some wires is cutting under the board and just resold it make the good signal for rom

By Grauw

Ascended (8513)

Grauw's picture

02-07-2015, 21:17

Alexey wrote:

Ok, here's the board with 4 4464 chips (128kb) and a pad to solder the airwire to CAS 0/1 of the VDP. If the board's CAS connector is routed to VDP's CAS0, then the airwire must be connected to CAS1 and vice versa.

I am not going to produce these boards myself unless I have at least 5 orders. Otherwise I can't even cover the expenses of making those boards. I am going to order my other boards soon, so if you need this VRAM board for your CX5MII MSX, please contact me ASAP.

If you want to produce these boards yourself, I can share the schematics and Gerber files. The only thing I will ask in return is 1 of these boards. I think it's fair enough.

Got enough orders yet?

By Alexey

Guardian (2446)

Alexey's picture

03-07-2015, 00:00

Only one. So no go for production...

By sd_snatcher

Prophet (3092)

sd_snatcher's picture

03-07-2015, 00:33

I don't have this machine, but I'll try to help. I'll ask if anyone wants one in the Brazilian mailing list, ok?

Just to confirm: If I got it right, this board can be used to upgrade VRAM on the following machines:
- Yamaha CX5M II
- Yamaha CX5M II/128
- Yamaha YIS-503II
- Yamaha YIS-503IIR

CX5M related machines where it's not needed (already MSX2)
- Yamaha CX7M

CX5M related machines where it won't fit:
- Yamaha CX5M
- Yamaha YIS-503
- Victor HC-5
- Victor HC-6

Uncertain:
- Victor HC-60

Any other models for each category?

By Alexey

Guardian (2446)

Alexey's picture

03-07-2015, 09:22

Thanks for your help. But please keep in mind that this board has not been tested yet. So there's no guarantee that it will work. Besides, it requires soldering if 4 chips are installed. So some people won't be able to install it themselves...

By Grauw

Ascended (8513)

Grauw's picture

03-07-2015, 13:29

Even without soldering that wire, it’ll still work as 64K VRAM though (screens 5 & 6).

By Alexey

Guardian (2446)

Alexey's picture

03-07-2015, 15:15

For those who want to make these boards, the production + shipment will cost 24 euros for 10 boards at www.pcbway.com. Just ask them for airmail shipment as this option is not available yet in their webshop. The quality of boards is quite decent.

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