+mizapf Posted July 14, 2020 Share Posted July 14, 2020 AFAIK the CC40 has a TMS7000 CPU, i.e. an 8-bit CPU that has a completely different instruction set than our TMS99xx systems. Quote Link to comment Share on other sites More sharing options...
+acadiel Posted July 15, 2020 Author Share Posted July 15, 2020 21 hours ago, pnr2015 said: How is the variant different? Where does it come from? It’s larger than the other one you disassembled, running around 6K or so. Probably had additional functionality. It was shoehorned into the same PCB and had extra wires soldered from the 8K chip to the PCB. Atrax, can you get us some good pictures from Lee? Quote Link to comment Share on other sites More sharing options...
atrax27407 Posted July 15, 2020 Share Posted July 15, 2020 Just sent a message - hope to have pics soon. Quote Link to comment Share on other sites More sharing options...
atrax27407 Posted July 15, 2020 Share Posted July 15, 2020 According to Lee, the original came from Richard Fleetwood in 1985 1 Quote Link to comment Share on other sites More sharing options...
atrax27407 Posted July 16, 2020 Share Posted July 16, 2020 According to Lee, the original came from Richard Fleetwood in 1985. Instead of a TMS2532 as in the prototype earlier in the thread, this chip was a 28-pin TMS2564. So, Lee is trying to replace an 8K TMS2564 with a 2764 using Brain's adapter. He is still going to have to run the wires, though. Quote Link to comment Share on other sites More sharing options...
+acadiel Posted July 17, 2020 Author Share Posted July 17, 2020 I do see wires hooked up to (on the 2564): 1 - Vpp 2 - Cable Select 1 14 - Vss 27 - Cable Select 2 28 - Vcc We're just dealing with CS1 and CS1, ground and +5V here. Usually, with those two cable select pins - they are invoked to power down the EPROM or make it active. My guess is that they're just hooked with all those wires in that they conform to the truth table to keep the EPROM active. The rest of the pins support a standard 8K 2564 24 pin EPROM. Quote Link to comment Share on other sites More sharing options...
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