Apple IIgs 256k -> 1MB memory upgrade problem

[+eebuckeye]

While I am looking for a 4MB card for my IIgs I have been trying to upgrade my Apple 256k memory expansion card to 1MB.

 

I ordered these:

 

http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?search_type=jamecoall&catalogId=10001&freeText=41256&langId=-1&productId=41398&storeId=10001&ddkey=http:StoreCatalogDrillDownView

 

and I received a mix of these chips:

 

NEC D41256C-12 9529B8A04

SIEMENS 8942 HYB 41256-12

SIEMENS 8936 HYB 41256-12

SIEMENS 8938 HYB 41256-12

SIEMENS 8937 HYB 41256-12

F MB81256-12 9348 M95 CD

Of course the original chips installed for 256MB are TI TMS4256-12NL IGE8901.

I installed the memory and received a few errors with the official Apple IIgs diag disks (in fact one of the errors pointed to one of the original 256k chips - UA8). I did have both jumpers installed. I performed the memory diag test with no extra chips installed and the base 256k passed.

I moved the memory to another expansion card that looks like it has never been used before. When I run the diags it says the incorrect memory amount is installed. Again I placed both jumpers on the card and made sure the pins were shorted with an ohm meter.

I also tested both cards with two different IIgs systems and received the same errors. The chips were installed correctly with pin 1 in the right location and I actually had another engineer look over the install and card.

This is starting to drive me nuts. :-) At this point I just want to get 1MB working.

Any suggestions? Thank you!

 

[jamesk]

I know when I ordered DRAM from Jameco to fix a IIc, several of the chips didn't work. I had diagnostic failures and some of the chips got real hot. Jameco sent out replacements without any hassle. So it may just be that they sent you some bad chips.

 

I don't know if mixing manufactures would pose an issue.

[Muzz73]

I seem to think that some IIgs RAM cards (but not all) used odd RAM, too. I heard somewhere that they need RAS/CAS addressing instead of CAS/RAS or some silly thing. I don't even know what all of that means, but I was told that back in the early 90s.

Edited January 7, 2015 by Muzz73

[+eebuckeye]

I finally was able to get it work by trying multiple sets of chips (trial and error). It did not seem to like any of the Siemens chips.