TXG/MNX Posted November 14, 2016 Share Posted November 14, 2016 Hello 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 Quote Link to comment Share on other sites More sharing options...
Fletch Posted November 14, 2016 Share Posted November 14, 2016 I seem to recall that those boards were limited to 2.5mb Quote Link to comment Share on other sites More sharing options...
Lynxman Posted November 14, 2016 Share Posted November 14, 2016 (edited) 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 November 14, 2016 by Lynxman Quote Link to comment Share on other sites More sharing options...
TXG/MNX Posted November 15, 2016 Author Share Posted November 15, 2016 thanx I put this on my to-do list for now it stays @2,5MB are there schematics of the 520ST somewhere to download ? Quote Link to comment Share on other sites More sharing options...
rpineau Posted November 16, 2016 Share Posted November 16, 2016 You can find the schematics there : http://dev-docs.atariforge.org Quote Link to comment Share on other sites More sharing options...
vattari Posted November 24, 2016 Share Posted November 24, 2016 I have a 1040ST with the same board. It also currently shows 2.5 MB Sent from my SM-T810 using Tapatalk Quote Link to comment Share on other sites More sharing options...
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