Amiga 3000 zip ram problem

[SpeedGeek]

There is a clock speed jumper for Ramsey (J851) and a clock 90 jumper (J100) both need to be set for 16 or 25 Mhz. Most A3000's are 25 Mhz. But it's a good idea to check jumpers in any case. Your problem is most likely an open connection to any one of the ZIP chips. Could be a bent pin, poor solder joint or broken trace. If the OS can't find memory in the first bank it won't bother to check the others. It's worth the effort to fix the problem. ZorRam will only run at 2/3x speed of motherboard fast memory and supposedly only works with SuperBuster rev 11. As far as the 42 Mhz FPU mod, someone went to alot of trouble to do this. There's a simple cut and jumper mod on Aminet/hardware/hacks to run the FPU from the motherboard 50 Mhz oscillator. You won't see a big performance boost since the FPU is seldom used by the OS. Looks nice on Benchmark programs though.

[SpeedGeek]

I checked with a multi-meter, the DIP and ZIP sockets are connected on bank 0; seems ok to me and I just don't like to remove the motherboard completely... Yes, I'm trying to
The 1 meg Zips use one more multiplexed address line (ADDR 9) than the 256K Dips use. But if your sure you have continuity from the Dip to Zip sockets on all pins then the open connection could be from Ramsey to the Dip sockets. Also, J852 is long way away from Ramsey so I would check for possible open connection there. One side has +5V, the other Ground and the center to Ramsey pin 12. A3000 Schematics can be downloaded from many websites. A good small program from Aminet is Checkmem. Use the "Force" option to check areas outside of the memory list and use with Cpu Nodatacache.
Can someone post a ShowConfig output of his A3000 with FastMEM on the motherboard ? Thanks
RAM: Node type $A, Attributes $505 (FAST), at $7000000-$7FFFFFF (16.0 meg)

[SpeedGeek]

Now for the A3k mb zip sockets, I did put the chips with pin 1 toward the caps, on the left when looking at sockets from the from of the A3k. Is that ok ?

Yes, thats correct. Bank 0 is from U850-U857. Now you need to find out why they don't work in the Zip sockets. If you have a PLCC extractor tool you could try removing Ramsey and reinstalling it. Also, it would be easy to do a continuity test from the Zip sockets to the Ramsey socket after the chip was pulled.