ATRAM 512KB ST(M) upgrade to 2MB

[troed]

[work in progress]

Bought a 520 STM yesterday, which the seller had said had been upgraded "to a 1040". I expected to see the regular piggyback when opening it up, but instead found a Marpet style upgrade courtesy of AT (of AT-Speed, I presume) - an ATRAM.

It has 4 chips of 256x4 - and just as I've upgraded a 520STFM with that configuration to 2MB I plan on exchanging these for 4 chips of 1Mx4. These are rare as DIP, so I'll use SOJ to DIP adapters as I've done previously and steal the chips off some SIMMs.

Is this smart, considering the known issues with pushing pins down MMU sockets? No, not really. But I'm doing it for the fun of it, not practicalities ;)

(Also, for those wondering about my mostly-absence the last year - that's called work and kids. However, moving to a [very] large house in 2 months where I will have a proper dedicated retro workshop/room so hopefully I'll be able to play around more then again)

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