Michael Karas wrote:
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You are absolutely correct Mikkel. The _*_Original_*_ IBM PC parallel adapter board as it was called used a small handful of TTL and LSTTL chips. For those interested I made a scan of its schematic so you can see how the ports connect to the DB-25 parallel connector.

I have the same schematic in a book. I used it for inspiration when i designed an 8-port printer interface a couple of years ago.

That schematic should also answer all the printer port questions for people needing printer ports on 8051 projects...

Best regards,

Mikkel C. Simonsen