DAC from SN76489 chip. BJT based.

183

01:39:15

4-bit DAC from SN76489 sound generator chip from the 80ies. It was popular with 8-bit machines: BBC Micro, Tandy 1000, Sega Master System, etc.

I am doing this reverse-engeneering effort to create a replica ASIC for SN76489:
https://github.com/rejunity/tt05-psg-sn76489

published 2 years ago

roops1967

2 years ago

rej I've surfed through some of your stuff following your Twitter link and I've become a fan 😀 ! I'm looking at your circuits here in your history and they're clever unique designs! I'll admit tho these last 2 circuits have me baffled, is it norm to use semiconductors as the resistive components in ASICS? I've got a few FPGAs but they're probably different beasts, I ain't got around to learning verilog/vhdl yet. I cut my teeth on the BBC model B , I guess you would be a UK resident too 😉

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