On Mar 24, 2013, at 3:38 AM, Lawrence Wilkinson <lawrence at ljw.me.uk> wrote:
I've been working on an IBM Selectric typewriter
which I bought earlier in the year. It is the I/O Selectric type 735 which differs from a
normal Selectric in having the solenoids and switches on it to allow it to be used as a
printer and keyboard.
When I got it the motor wouldn't run, and the mechanism was jammed. The motor problem
was its thermal trip, which is meant to be the resettable type, so I replaced that. I
gave the whole thing a clean with degreaser, which freed up the mechanicals, then oiled
and greased it. It then worked happily as a typewriter.
I have made a small interface, based on an Arduino Mega 2560, which provides a serial
port. Currently this only supports printing, but will be extended to include the
keyboard. It uses almost all the digital I/O on the Mega (15 solenoids, 27 contacts.)
There are still some adjustments to be done, and I am awaiting a set of Bristol Wrenches
(Keys) so I can safely do these. I have tried using Torx and Allen keys, and while they
can be made to 'fit', it doesn't seem like a good idea.
There are some pictures and videos of the typewriter here:
You can get the Arduino interface code here: https://github.com/ibm2030/IOSelectric
I haven't yet documented the hardware I used for the solenoid drivers, but if anyone
is interested I can put some notes together (basically: Arduino output to 2N7000 FET
buffer to ITS4140N +48V high-side driver on the output side, and a simple 250R pullup to
+5V on the input side.)
Manuals here: http://bitsavers.informatik.uni-stuttgart.de/pdf/ibm/typewriter/selectric/
(or other Bitsavers mirrors)
Info on the Mega2560 here: http://arduino.cc/en/Main/arduinoBoardMega2560
When I was in school (35 years ago) I had an IBM 1052 terminal that I interfaced to an
8080. The issue with the 1052 was that the relays were all 48v so finding drivers was
It took me a bit of fiddling with the timing to get it to print properly (at 134.5 baud).
It sure beat the ASR/KSR-33s that most other folks were using for their terminals just for
the "cool" factor!
TTFN - Guy