Yamaha CX5MII/128 Upgrade to MSX2

Pagina 2/4
1 | | 3 | 4

Van grit

Resident (53)

afbeelding van grit

05-11-2007, 09:35

Yes, this is the link I mean, my mainboard s is nothing like the mainboard on my CX5M-II service manual or on this link. My board says xb300 and has all videoram on he mainboard itself. I can't see RTC space on that board either.

Van Jipe

Paragon (1504)

afbeelding van Jipe

05-11-2007, 11:25

the schematic is the same only RTC miss
how many size as your video ram and how many IC
if is 16 ko you desold all IC and sold 2 x Ram 64k x 4 but is not same pinout
you can make a little board or sold on PCB with wire

Van grit

Resident (53)

afbeelding van grit

05-11-2007, 19:09

I'm telling you I have a different mainboard... look here:
board:
http://www.rgp.nl/cx5m/DSC00014.JPG
vram section (topleft):
http://www.rgp.nl/cx5m/DSC00013.JPG (before)
http://www.rgp.nl/cx5m/DSC00015.JPG (After)

IC's have different numbers, no seperate 16kb vram stuff

Van Jipe

Paragon (1504)

afbeelding van Jipe

05-11-2007, 23:29

my CX5MII is not the same but i have a friend with a CX5MII with this vram
i conctact for saturday and take many photos with the modification
i have added a clock on additional PCB and 4Mo memory
but i have no schematic and no photo
the clock of CX5MII is the same of VG8235

Van grit

Resident (53)

afbeelding van grit

06-11-2007, 08:26

well I'm very curious what you'll find. The circuit for the rtc is indeed not very difficult, but I'll-might-get-to-that - if the rest finally works. I'll detach the mobo and take some pictures today too.

Van dicksch

Supporter (6)

afbeelding van dicksch

10-11-2007, 11:15

I have also a Yamaha CX5MI/128 and have made the changes to the VRAM which was on the main board. I have burnt the EPROMs for MSX2 and made the changes by connecting the subrom to address to 0000. I was able to obtain a SONY floppy drive (MSX is very scarce in Canada). The machine boots fine and comes up with the MSX2 Basic and MSX2 Disk Basic and indicates 00KL and 128K memory during the logo on booting, but I cannot boot to DOS. I have tried creating the diskettes but an so far unsuccessful. Do I have to make changes to the memory mapper? I suspect may have a memory problem so does anyone have a basic program that will test my memory. Was there a change to be made to the CX5MII memory mapper to make it work? I have the rom with no clock. I cannot recall where I obtained the image. I have also obtained the SUN IDE interface and am able to boot from it but alas still cannot get into DOS. It sems to hang or loop. Any help would be appreciated.

Van Jipe

Paragon (1504)

afbeelding van Jipe

11-11-2007, 19:25

the CX5MII of my friend are the same PCB

you can see the pictures of the additionnal clock on this french web site

http://www.msxcafe.com/modules/xcgal/index.php?cat=10005

Van grit

Resident (53)

afbeelding van grit

12-11-2007, 08:42

hey, that's cool, once I get the roms done I'll check that out surely, thanks!

Van Jipe

Paragon (1504)

afbeelding van Jipe

12-11-2007, 14:15

the rom are copy of 8280 in this CX5
8250 works also

Van grit

Resident (53)

afbeelding van grit

12-11-2007, 15:00

Well I got it working, the IC# for this board is IC16 for the MREQ signal. Thanks all for the help

Pagina 2/4
1 | | 3 | 4