[Coladam] Memory expanders

Ellen and Craig Lindholm eclindholm at gmail.com
Sat Dec 11 05:59:33 CET 2010


I have been looking into redesigning a memory expander (larger than 64k  
which is trivial) using modern SRAM components.

When I get it done, I will be releasing the design to the community. The  
trick has been in designing it to be compatible with all the existing  
software and that has proven to be the most frustrating part as I can't  
find ANY information on how to actually access the existing cards! If I  
can figure how the existing software accesses the extended memory, It  
should be pretty simple to design the card with modern components. I know  
that the existing cards use the second slot for addressing purposes, but I  
have yet to determine which lines are used for the address decoding.

Does anyone have information as to how the addressing is done with these  
old cards? Even some sample assembly code that accesses the memory  
expanders would help as I can determine what the hardware is doing from  
the instructions.

Best Regards and have a Merry Christmas

Craig Lindholm


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