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Memoryboard Atari 520st

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I just opened a 520st to clean. It has an memory expesionboard at bootup it tells me that it has 2,5MB.

Can I add more memory to this board will it then 4mb or 4,5mb?


Don't have a manual or name of this upgrade.




Sent from UMI hammer with Tapatalk

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You can add additional 16 pcs 1Mx1 chips (120ns or faster). But you have to deactivate the 512Kb on Board.

Connect RAS0 and CAS0x lines at Memory chip side of the internal 512Kb to +5V. Or remove the internal 512Kb.

Check if RAS0 and CAS0x from MMU side is connected to the unpopulated sockets.


Maximum memory for 520ST is 4MB. (without additional logic)

Edited by Lynxman

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