HP9810A alive again!

Mattis Lind mattislind at gmail.com
Thu Nov 6 08:38:49 CST 2014

After replacing a lot of dead National Semiconductor TTL ICs this nice
little machine from 1972-1973 is running again. It works perfectly to do
calculations and also to create programs. I also managed to both store and
restore a program written onto a home made magnetic card. Home made since I
wasn't able to find any.
There are a few issues left: The belt in the card reader is slipping a bit
so a replacement would probably be needed to get it working 100%. One
segment in the display is dead.

Anyway: Here is the writeup of the restoration:

and here is a video-clip: https://www.youtube.com/watch?v=C9rBoWvze48



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