A3000 Fast RAM query

[alektronic]

Hi all (first post!)

I've recently rescued an A3000 which has 1Mb of Chip RAM and 1Mb of Fast RAM.

I've been keen to get a bit more Fast RAM into it and managed to find four 1Mx4 ZIPs, which should be 2Mb.

I've moved the DIPs over from the Fast RAM to the Chip RAM sockets and changed the jumper, as stated in the manual (J852). The four ZIPs are correctly seated in the first four sockets of bank 0 (U850, U851, U852, U853) so theoretically I should have 2Mb Chip and 2Mb Fast RAM.

However, on booting, Workbench shows zero Fast RAM... Have I gone wrong?

Can anyone confirm if this is a workable configuration? Or do I need another 4 chips of the same type, in order to completely fill bank 0?

Is there any way to test the ZIPs I have, before I go and try to find similar compatible ones?

Thanks!

[zipper]

Not an owner - http://amiga.resource.cx/mod/a3000.html
>> The ZIP DRAM sockets accept either 1M×4 or 256k×4 80 ns ZIPs in groups of eight (one bank) but all the banks have to have the same sized chips

[idrougge]

With four bits per ZIP and four ZIPs, you get 16 bits. The A3000 is a 32-bit machine and needs 32 bits per bank.

[alektronic]

Ah, that all makes perfect sense, thanks both!