Final Update: It WORKS!
Did a complete check of everything and changed some of the ICs (which I did not think are broken, need to test them on my tester)
I think I forgot the last wire of the last step ...
At least the computer now sees all 1024 Kb and running testram and maptest4.2 there are no errors present!!

He OeiOei, going to try your old board again?

Quote:

Final Update: It WORKS! Did a complete check of everything and changed some of the ICs (which I did not think are broken, need to test them on my tester) I think I forgot the last wire of the last step ... At least the computer now sees all 1024 Kb and running testram and maptest4.2 there are no errors present!! He OeiOei, going to try your old board again?

Congratulations. Good to hear the modification works and the instruction is correct.
Any suggestions to improve it?

What's the meaning of "cut the pins 1 t/m 6 and 8 t/m 13 half"?. I'm not totally sure about it...

Quote:

What's the meaning of "cut the pins 1 t/m 6 and 8 t/m 13 half"?. I'm not totally sure about it...

It means that you take the new IC and cut the thinner part of the whole pin.
Each pin is wider at the top and thin at the bottom. As you don't want to have that pin connecting to the IC where you put it on you remove some part of the pin.
So you still could need solder a wire to it if needed.

Quote:

Congratulations. Good to hear the modification works and the instruction is correct. Any suggestions to improve it?

Well the general instructions are pretty good to read. Had some trouble in the beginning with the 74LS670
as 2 wires are soldered to the version on the PCB and some on the added IC.
Also if someone has a schematic of the added logic to the original mapper it might help checking too.
I drew a (very bad) picture of the new mapper to see the new logic and so it was easier to check all the wires on the mapper logic.

Oh and one last thing, this could help a lot for people who are not that experienced:
I removed first the memory ICs and put sockets in. That way I was able to see if all the wires are still in one piece on the memory part of the PCB. So you then put the memory back in and see if the machine still works.
You only need 2 and put them in socket 133 and 134. If you have 4 it is even better.
Without the memory ICs an external memory cartridge also helps.

After that I put in all the ICs and wires and tested again with the old memory
then I connected the SIMM.
This way you can trace your fault a little better then doing everything at once as it is very easy to make a mistake.

Quote:

What's the meaning of "cut the pins 1 t/m 6 and 8 t/m 13 half"?. I'm not totally sure about it...

I think it means "cut the pins 1 TO 6 and 8 TO 13", but only the thin part (half pin).

Ok, I see; the "half" part is now clear; but the "t/m" (TO) thing is a typo then?

the 't/m' is typical Dutch. It is 'tot en met' in Dutch it means all the pins 1 2 3 4 5 6 (1 t/m 6)

Quote:

the 't/m' is typical Dutch. It is 'tot en met' in Dutch it means all the pins 1 2 3 4 5 6 (1 t/m 6)

Indeed, a translation 'leftover'. I will try to correct the english version with these remarks.

Any chance of giving me the mapper circuit digram you have drawn? even if it is not that good it is better than what we have now!

Let me redraw it and scan it in tomorrow. Where can I get your email address?
Quickly scanned your site but did not see it immediately

Quote:

Let me redraw it and scan it in tomorrow. Where can I get your email address? Quickly scanned your site but did not see it immediately

This will work: msxhans (at) yahoo (dot) com

If anyone wants to try it out them selfs i have some 1Mb Simms left and you can have them for 50 cents a piece.And shipping of course.
I didn't check all of the simms so some can be broken
Just send me a mail at sokolowski1 -at- zonnet -dot- NL

I have build the 1 Mb expansion in to my 8280 with the explanation on HansO his site
and it works perfectly.

id like the "updated" version of the thingy too

BTW, are there any RAM expanding guides for Yamaha MSX2 machines ?

Quote:

id like the "updated" version of the thingy too

Bring your msx to the next MvM meeting and we can have a look at it