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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: Ianoakley on July 23, 2008, 10:06:15 PM

Title: Amiga 4000 Chip Ram
Post by: Ianoakley on July 23, 2008, 10:06:15 PM
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 ?
Title: Re: Amiga 4000 Chip Ram
Post by: LoadWB on July 23, 2008, 10:47:43 PM
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.
Title: Re: Amiga 4000 Chip Ram
Post by: boing4000 on July 24, 2008, 12:02:54 PM
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.
Title: Re: Amiga 4000 Chip Ram
Post by: Zac67 on July 24, 2008, 06:36:30 PM
- misposted -