[Coco] 512K/1M/2M512M CoCo 3 Upgrades - Some Work Towards That Goal

[Little John (GIMEchip.com)]

I have posted some of this here:

http://www.coco3.com/community/2010/07/more-on-coco-3-memory-upgrades-512k1m2m-from-gimechip-com

I am hoping fellow list members may be able to spot potential problems with this design. I hope to get a functional 2-Meg upgrade ready soon, but I've got to test these equations first. - Thanks All - John

This is my proposed method of allowing the use of DRAM requiring a 512-Cycle refresh in a CoCo 3 512K/1M/2M RAM Upgrade. If I have gotten this correct, then it should be possible to make a 5-chip 512K RAM Upgrade (four 256Kx4 DRAMs plus the GAL 16V8), or to use Any 30-Pin or 72-Pin SIMMs in a CoCo 3 SIMM Upgrade. The Equations below should tell the story if you examine them, or preferably, download the WinCUPL file for better formatted text. Simply unzip the download and load the ".pld" file into WinCUPL or a text editor. Let me know if you spot anything that seems as if it will not work. Getting these equations working properly (I have yet to test them) is the key to my proposed 2-Meg and 512-Meg Upgrades. Once the memory board has been worked out, the DAT Board is child's play - you could simply Copy DISTO's DAT Board, but my design uses a SRAM and Multiplexers, etc. and also allows the added DAT bits to be read back (they are write only in DISTO's 2-Megger). I have generated PCB Layouts for both a 5-chip 512K and a 30-Pin SIMM 512K Upgrade intended to use the PAL generated from these equations, however all of this needs to be tested before I decide to order any boards - I'm hoping you guys can let me know if this looks feasioble and correct.

Thanks All - John
512KAnySIMM_PLUS_512K-44256_PLD-Equations(GIMEchip.com)





http://www.coco3.com/community/2010/07/more-on-coco-3-memory-upgrades-512k1m2m-from-gimechip-com