Bank-switchable memory for the Altair 8800
Posted: October 8th, 2023, 11:43 am
What's the best memory board for a banked-memory Altair?
I'd like to create a version of CP/M 3 that supports the IDE drive and banked memory. Right now - without banked memory - TPA is 47Kb. I think that could be bumped up 8Kb or so with maybe a 48Kb swappable bank.
Seems like a Cromemco memory would be great, but I think those things are probably pretty rare. I think it would be useful to have a memory board with 112Kb and a dip-switch configurable bank-control port address. Bottom 48Kb is bank-switched, and top 16Kb is common. Maybe even give it additional provisions to swap out boot ROM up top too.
I've seen larger memory boards than this for S100 systems, but most seem to favor a flat address space for use with processors made after the 8080. I'm not really interested in that 'cause the original 8080 can't use the extra memory. But a switchable pair of banks to swap out portions of the operating system to make room for transient programs would be great.
I'd like to create a version of CP/M 3 that supports the IDE drive and banked memory. Right now - without banked memory - TPA is 47Kb. I think that could be bumped up 8Kb or so with maybe a 48Kb swappable bank.
Seems like a Cromemco memory would be great, but I think those things are probably pretty rare. I think it would be useful to have a memory board with 112Kb and a dip-switch configurable bank-control port address. Bottom 48Kb is bank-switched, and top 16Kb is common. Maybe even give it additional provisions to swap out boot ROM up top too.
I've seen larger memory boards than this for S100 systems, but most seem to favor a flat address space for use with processors made after the 8080. I'm not really interested in that 'cause the original 8080 can't use the extra memory. But a switchable pair of banks to swap out portions of the operating system to make room for transient programs would be great.