[Coco] CoCo3 memory expansion questions
farna at att.net
Mon Feb 4 06:35:32 EST 2019
Date: Sun, 3 Feb 2019 13:03:10 -0500
From: Neil Cherry <ncherry at linuxha.com>
Actually there is a very cool 'hack' for the SWTPC which uses a pairof 74189s (64bit RAM). It allows each process to have it's own memory.
Unfortunately I'm not sure if OS9 supported DAT ram. This gave the
6809 access to 1M in 8K pages.
That's similar to what the CoCo3 GIME does. I believe it uses 8K pages of memory switched in and out... if not someone will correct me! Could be a different page size, but it's a big chunk of memory, I do recall that...I wonder if you could implement something on a separate board? The GIME functions have been worked out for the FPGA systems and emulators, so the info is out there. I don't mean the entire GIME (which also processes video), just the memory management function. With that you should be able to expand memory and modify Nitros9 Level II to work. Not sure what all would have to be modified though...
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