Back in the late 70s early 80s one of Dad's work colleagues came up with this circuit for interfacing an IBM I/O Selectric to a microcomputer. We had one, which we planned to use with our Fairchild/Mostek F8 development board, but it never got done - my brother and I wanted a computer with a screen, not a printer! So we spent our pocket money (and Dad's too) on an S-100 kit system, but that's another story. Recently I found the only remains of our I/O writer, the platen. Sadly I think it must have been junked, the platen being kept to roll out photographic prints in Dad's darkroom.
I just finished scanning, cleaning up the degradation and turning the circuit into a PDF. These days an Arduino or RasPi would be a simpler and more flexible way to go, but I hope you find it interesting looking at how it was done with TTL and discrete components. The circuit was designed by (I believe) Neil Taylor, possibly with the help of Derek Williamson, both brilliant IBM Australia CE's. I know my dad always spoke very highly of them. It's an 8-page PDF at http://web.aanet.com.au/~malikoff/misc/IBM_IO_Selectric_interface.pdf Regards, Steve Malikoff.
