| Re: Has anyone reverse engineered SP0256A external serial speech ROM [message #10769 is a reply to message #10767] |
Fri, 17 May 2024 04:14   |
lynchaj
Messages: 1080
Registered: June 2016
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Senior Member |
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Hi Bill
Wow! That's great news! Looks good
Regarding ASRLD and PCLD commands, the SP0256B datasheet goes into detail of its implementation. I believe it needs to be a 16-bit counter for the address bus based on the text. Below is a snippet from the datasheet
Am I correct in assuming the current design will fit in a EPM7064 but not an EPM7032 due to using 60 cells?
It's not clear to me what STACKLD or RETURN are even used for so they may not be included in the SP0256 implementation. Maybe they are leftovers for some other purpose?
Awesome progress! Thank you! Andrew Lynch
PS, maybe you're already doing that. What is component inst12? It looks like a 16-bit D-flip flop maybe serial to parallel converter? The design seems amazingly simple in the schematic layout. Many fewer parts than I anticipated.
PPS, I am guessing inst27 component is a 74LS74 D-flip flop. Is inst12 two 74LS164s chained together to make a 16-bit serial to parallel converter? What is inst13? three 74LS191s chained together? 74LS161 or 74LS163s? This is very interesting.
Can't wait to see how this does in test!
[Updated on: Fri, 17 May 2024 05:05] Report message to a moderator |
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