CX5M expansion

By Robby

Master (173)

Robby의 아바타

15-10-2014, 16:31

Hi all,

I have a question about my CX5M. It says it has a sort of memory expansion (not done by me) which can be activated at the back of the machine.
After openened the case, also the folowing tekst is written down:
"Customized slot select. Special designed for ext. slot unit. connected to exp. slot (2). In standard (32k) mode exp. slot n.c. >> (disc I.F)."
Does anybody recognize these text, or knows what has been modified. When i boot the msx i can only start up with the swith on 32kb enabled, on 64kb enabled it will not boot. Any ideas?
Thanx in advance Smile

RJ.

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By Robby

Master (173)

Robby의 아바타

16-10-2014, 13:25

Anybody?
Of course i know its an expansion from 32k to 64k, but because its not working (64k) maybe the previous owner is also here on the forum. Or somebody else know's how to get it working (?).

By rolins

Champion (418)

rolins의 아바타

17-10-2014, 05:03

You sure this mod is for 64k? The ram chips (MB81416-12) are located next to the vram. Check if they're modified.

The mod could be for slot expander or some special unit for slot 2 that the original owner made himself. It's an interesting mod.

What does the red button do? A reset switch?

By Robby

Master (173)

Robby의 아바타

17-10-2014, 14:34

Hi,
Now that i've took a second look, i also doubt it's a 64k mod. The red button is for a reset indeed. When i read the written text again on the picture above, i also think maybe it's made for a slot expander (as called a "external slot unit, connected to the expansion slot, slot2). Maybe slot 2 is splitted or something, to get a slot expander working correctly?
However, i still don't understand why the swith to "64k" wont work. All wires seems to be soldered fine ( so far my technical skills Wink )
Hereby some additional pictures. As you could see the original ram chips you mentioned are still present, unmodified.

Another view of the current mod:

RJ.