Amiga 4000 Chip Ram

[Ianoakley]

I've tried several sticks of memory in the chip ram slot but when I boot up and use show config it reports that I've only got 1MB of chip ram. All the modules are likely to be over 2MB. Finally I fitted an 8MB simm and got my 2Mb of chipram !

I know J213 does not have any bearing on this. Does anyone have an explaination for this strange issue ?

[LoadWB]

Without getting to in-depth, essentially "sidedness" is at work.  For instance, 1MB, 4MB, and 16MB SIMMs are single-sided, while 2MB, 8MB, and 32MB SIMMs are double-sided.  Since the ChipRAM slot expects 2MB (and addresses that much at most,) any double-sided SIMM should work, and larger capacities will be seen as only 2MB.

Even though physically some 8MB and 32MB sticks are single-sided, they are still double-sided logically.

[boing4000]

To gain 2MB Chipram with an single sided PS/2 module, set both jumpers to "8M".
This works very fine in my A4000D with a 2 Chips 4MB module for years.

[Zac67]

- misposted -