Parallel Interface for the Clone

General discussions related to the Altair 8800 Clone

Parallel Interface for the Clone

Postby MajorClements » December 31st, 2022, 12:27 pm

Could a Parallel interface be created for the clone using traditional Shift Register ICs? I understand that the serial port bit rate is software limited to 9600, but since the clone can kick up to 115,520 could the firmware be updated to support such a feat? (perhaps even higher than the 115k?) Honestly, from a Computer Engineering perspective, I don't see why it cannot be done, unless I am missing something in my way of thinking.

BTW, I began restoration work of my 8800 Clone, I have to say, Solder Flux makes a tremendous difference!
Sincerely,
Daniel
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MajorClements
 
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Re: Parallel Interface for the Clone

Postby Wayne Parham » December 31st, 2022, 2:34 pm

MajorClements wrote:I began restoration work of my 8800 Clone, I have to say, Solder Flux makes a tremendous difference!

True that!

MajorClements wrote:Could a Parallel interface be created for the clone using traditional Shift Register ICs? I understand that the serial port bit rate is software limited to 9600, but since the clone can kick up to 115,520 could the firmware be updated to support such a feat? (perhaps even higher than the 115k?) Honestly, from a Computer Engineering perspective, I don't see why it cannot be done, unless I am missing something in my way of thinking.

Sure, you can easily make a serial-to-parallel converter. I personally like using the old AY-5-1013 chip for that purpose. They're just so easy to use, and you can still get 'em.

Back in the 1970s, I made a handshaking converter based on that chip. It converted XON/XOFF handshaking to DTR/DSR (or RTS/CTS) for devices that could only support one or the other. The circuit gated the chips parallel output to "watch" for XON and XOFF, and asserted the hardware handshaking line accordingly.
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