All the chips are the same: SC.
I have the same problem with the 32 chips fitted. After system boot, 0 other ram 
EDIT: chips are 70ns
Dude, I've been there. If you have money, then don't waste your time and invest in ZorRAM (or ZIP to SIMM adapter if you will stumble upon one). Of course ZorRAM is a bit slower than on-board RAM, but it will save you a lot of headaches related to ZIP RAM chips...
My A3000 came with 4MB of Fast. I've tried to install more by adding ZIPs. Theoretically chips I've acquired were compatible with those installed in my A3000 - same type, same speed, installed in correct banks, etc. But it would never not work. In my opinion A3000 onboard RAM is extremely difficult do expand. Some people did this and had no trouble at all, but I've wasted many hours and got nothing! Finally I gave up and bought ZorRAM, which is an excellent RAM expansion.
