Re: I have a 15MHz IIgs!

[STYNX <stynx@gmx.de>]

The tests i have done regarding SRAm were on one of the most buggy ZIP GSX i have. It would look like the speed is a lesser factor compared to the type of SRAM. The 20ns Alliance i have tested as well were about as good as the Fairchild ones.  In the end it might be needed to swap chips around to get the best results. The main reason different Sram ICs were used was the Price of fast SRAM. The Data-cache can be slower (about 2-3 times slower than the Tag-ram), but as there are more than enough SRAMs on old 386-Boards ;-) i wouldn't hesitate to install 4 identical ICs. It looks nicer anyway :-P
The "me" UMC Chips i found to be problematic had an "me" in thick swirly handwriting font slightly displaced to the actual part number. But i can't say that they will not work with other cards! Try to find the the point, where the card will get stable. Then install a osc. that is a little faster (2-4mhz) if the card gives random errors, check if the card will work better with another cache IC. Keep in mind, that even if you can't get the card stable, it might be the osc. ;-). It will help if you have some stable ZIP GSX cards to actually test osc. and sram. 
The removal of the org. socket is not that hard. I used a Dremel-drill with a cutting disc to carefully remove the plastic bridges of the socket (don't touch the board in the process!). After that i could just install the additional (cut in half) socket (sometimes i had to desolder the holes in the middle of the socket). I did not bother to completely remove the unused socket. The remaining socket residue :-) will not hinder you in the following upgrade anyway. If the socket has to be completely removed there is the possibility to damage the Board. The result of a easy socket upgrade will not look as nice as a completely new socket but will do the same job. I mainly used a unsolder-iron and unsolder-wick.

Oh, before i forget: some later ZIPs seem to have been soldered rather badly. The card might need some solder joint to be resoldered if it will not be stable.

The reason, why i could be more or less carefree with my cards was, that they were given to me as spare  parts. I took more risks because I had no problems to completely destroy them in the process. I was happy enough as i realized, that i could get 4 of 6 to work. I'm working on the 5th card right now. But this one will need some retracing to be done and thats real work. The 6th card is dead (as far as i know).

greetings
-Jonas