Yamaha CX5M, CX5M II, CX7M

Página 3/5
1 | 2 | | 4 | 5

Por zPasi

Champion (499)

Imagen del zPasi

19-12-2015, 22:43

I see the Yamaha CX5MII wiki page has been updated.

There is an error however: "It can be easily upgraded internally because RAM and VRAM are each on an individual board with a connector. Simply just to change the corresponding board."

Apparently there have been multiple versions of CX5MII. For some that is true, for others it isn't. Like I wrote, mine is XB300 board version, and in this one, the VRAM is soldered directly to the main board. The main RAM (with mapper) is on a daughter board though.

I know I too could edit that wiki page, but what should I put there? I don't know how many versions of CX5MII have been made.

Por zPasi

Champion (499)

Imagen del zPasi

31-01-2016, 21:11

I'm trying to build that MSX2 upgrade.

To make sure I don't kill my precious CX5MII in the process, I bought a YIS503IIR motherboard. It should be almost the same, but with that VRAM daughter board connector. I'm not sure if to buy this was such a great idea, though.

What I didn't notice, also the main memory connector(s) is different so I cannot easily reuse the existing 128K main RAM. And probably the Russian BIOS is encrypting the keyboard, but I'm planning to change that BIOS anyway ... Tongue

For testing, I plugged in my home-made external RAM mapper. Then I built (on breadboard, first) that VRAM circuit mentioned, with one 74HCT373 and a 128K x 8 SRAM. It almost works.

Space Manbow runs, but with glitches and then freezes. Aleste 2 runs, sometimes even the menu and backgrounds display ok, but sprites are mess. Some MSX1 games work perfectly, like Kung Fu 2 and Salamander, others don't (Nemesis 2). Interesting.

So the circuit cannot be very wrong. I guess my 373 or SRAM (70ns) is too slow, maybe both.

Here a picture of my beautiful testing setup:

Por Alexey

Guardian (3375)

Imagen del Alexey

31-01-2016, 22:18

Terve, Pasi. If your CX5MII has CX7 motherboard, then you can do an easy upgrade of VRAM and RAM with these 2 ready-made boards:

In addition, the size and the component location of the CX7 board allows to install the internal FMPAC board:

As for your YIS503II board, you can use the same memory boards as for the CX7 upgrade, but you need to change the BIOS to MSX2 compatible that works without RTC chip (I can provide it if you need). Also you need to add the missing address line to the RAM board connector, otherwise your computer will not see more than 64kb of RAM. After that you will have an (almost) MSX2 machine, but without RTC.

About timing, AFAIR you can use any RAM chips that are not slower than 200ns for RAM upgrade.

Por gdx

Enlighted (5481)

Imagen del gdx

01-02-2016, 01:04

Increase VRam is only useful if you upgrade your CX5MII to MSX2/2+.

zPasi wrote:

I see the Yamaha CX5MII wiki page has been updated.

There is an error however: "It can be easily upgraded internally because RAM and VRAM are each on an individual board with a connector. Simply just to change the corresponding board."

Your quote is incomplete.

Quote:

It can be easily upgraded internally because RAM and VRAM are each on an individual board with a connector. Simply just to change the corresponding board. Some machines don't have a separate VRAM board but you can change the VRAM on the mainboard.

Also, I'm not sure but I think there is already the location for the RTC on the Main-board.

Por Grauw

Ascended (10578)

Imagen del Grauw

01-02-2016, 01:29

gdx wrote:

Increase VRam is only useful if you upgrade your CX5MII to MSX2/2+.

Just a matter of BIOS ROM at this point… no?

gdx wrote:

Also, I'm not sure but I think there is already the location for the RTC on the Main-board.

There is, and the circuit is described in the YIS503IIIR service manual iirc.

Por maxis

Champion (512)

Imagen del maxis

01-02-2016, 01:57

@zPasi, gdx, Grauw:

XB300 version MoBo has no place for RTC. And the main RAM daughterboard doesn't have a single connector, but 2 of them.

More over, there are 4 places on the MoBo to hold either 2x4416 or 4x4464 for 128K and no connector.

I do have a cx5mII/128 like that. These are usually the computers for the German market.

Por zPasi

Champion (499)

Imagen del zPasi

01-02-2016, 09:11

gdx wrote:

Increase VRam is only useful if you upgrade your CX5MII to MSX2/2+.

zPasi wrote:

I see the Yamaha CX5MII wiki page has been updated.

There is an error however: "It can be easily upgraded internally because RAM and VRAM are each on an individual board with a connector. Simply just to change the corresponding board."

Your quote is incomplete.

No, it's not. The wiki page has been updated since then.

Grauw wrote:
gdx wrote:

Also, I'm not sure but I think there is already the location for the RTC on the Main-board.

There is, and the circuit is described in the YIS503IIIR service manual iirc.

...which I don't have. Or is yamahacx5msm.pdf from hansotten close enough? I also found YIS503IIR.zip which contains just the schematics as GIFs.

Also, when upgrading the BIOS, I'd like to know what I'm doing. The BASIC rom goes to slot 0, and the extended BIOS parts (which are what?) to expanded slot 3-x and 3-y ?

Por zPasi

Champion (499)

Imagen del zPasi

01-02-2016, 09:24

Alexey wrote:

Terve, Pasi. If your CX5MII has CX7 motherboard, then you can do an easy upgrade of VRAM and RAM with these 2 ready-made boards:

Very tempting. Well, seems my real CX5MII board is not the same as CX7, but the replacement YIS503II should be. How much RAM is in your board?

Alexey wrote:

Also you need to add the missing address line to the RAM board connector, otherwise your computer will not see more than 64kb of RAM.

What? The mapper is in the RAM board, how could there be a missing address line?

Alexey wrote:

About timing, AFAIR you can use any RAM chips that are not slower than 200ns for RAM upgrade.

Normally yes, but I was trying to build the VRAM from a single 128K SRAM chip.

Quote:

In addition, the size and the component location of the CX7 board allows to install the internal FMPAC board:

I understand the Yamaha SFG-05 synth module is much better than FMPAC, so do I still need one? The SFG-05 is not compatible with games?

Por Grauw

Ascended (10578)

Imagen del Grauw

01-02-2016, 09:51

zPasi wrote:
Grauw wrote:

There is, and the circuit is described in the YIS503IIIR service manual iirc.

...which I don't have. Or is yamahacx5msm.pdf from hansotten close enough? I also found YIS503IIR.zip which contains just the schematics as GIFs.

It might be that one, I think the service manual between the IIR and IIIR is shared, but if not I can send it to you when I get home (but mine is all images as well so I think it may be the same one)...

zPasi wrote:

I understand the Yamaha SFG-05 synth module is much better than FMPAC, so do I still need one? The SFG-05 is not compatible with games?

Exactemundo. But you can also just use a cartridge, you don’t have to build it in, just saves a slot.

Por Alexey

Guardian (3375)

Imagen del Alexey

01-02-2016, 20:57

zPasi wrote:

Very tempting. Well, seems my real CX5MII board is not the same as CX7, but the replacement YIS503II should be. How much RAM is in your board?

The RAM board can have either 512kb or 1024kb of RAM. Note that CX7 is not the machine name, it's the board type that was inside some of CX5MII (probably later versions). If you have a different motherboard with 2 connectors, then this RAM module will not fit there. On CX7 board it works out of the box. On the Russian MSX1 mainboard you will need to do some modifications (see below).

zPasi wrote:

What? The mapper is in the RAM board, how could there be a missing address line?

Sorry, wrong info. By comparing the schematics you can notice that the KYBT1 YIS503II board is missing MAPWR and MAPRD signals that come from the mainboard. You need to install 2 logic chips on the board so that you could use the RAM module with 512-1024kb with it. So solder IC315 - 74LS04 and IC319 - 74LS30 on empty places on the mainboard:

Then you need to make sure that you upgrade the ROMs. The main ROM is 32kb and SubROM is 16kb. If you are not going to install RTC circuit, you can use this patched SubROM:
http://zx-pk.ru/attachment.php?attachmentid=34167&d=1332349512

Otherwise the normal ROM and SubROM for Yamaha MSX2 can be found here:
http://zx-pk.ru/attachment.php?attachmentid=34304&d=1332851844

The VRAM expansion board should work out of the box with MSX2 ROMs, but you need to solder one wire to the drilled out VDP line on the back side of the board to get 128kb of VRAM:

Página 3/5
1 | 2 | | 4 | 5