IBM Selectric-based Terminals

Paul Berger phb.hfx at
Tue Dec 15 09:37:07 CST 2015

On 2015-12-15 1:54 AM, Paul Birkel wrote:
> Looks very nice! Is there documentation for it somewhere? I also have 
> a Selectric (unfortunately it's located distant from me at the moment 
> so I can't provide particulars) that I worked on interfacing to a 
> micro in the mid-70's. I was using a MC6800 in my recollection, but I 
> don't believe that I ever achieved operational status. Presumably I 
> was working from an article in one of the hobbyist magazines of the 
> era. I would have guessed Byte, but that doesn't seem to be the case 
> based on recent search. Any hints from folks on what magazine/article 
> that might have been? The Selectric wasn't one of the curvy(ier) 
> office models; I recall it being a rather boxy affair with plenty of 
> right-angles on the housing and a medium shade of blue -- presumably 
> "IBM Blue". Rather utilitarian in design. Even *more* utilitarian than 
> this one: 
> It included a full keyboard. I'm not sure anymore whether it operated 
> in local-mode or was set up as two separate devices and therefore 
> needed to be connected up to a remote controller to get local copy. It 
> might have been a rehoused Selectric mechanism in a third-party 
> enclosure and the IBM-like color a red herring. My recollection is 
> that it was longer front-to-back; presumably the rearward extension 
> housed the additional electronics. I have absolutely no idea how I 
> acquired it. No luck finding a matching photo online as yet. I believe 
> that the Selectric came configured for remote operation, but 
> presumably using an EBCDIC-based data stream. I vaguely recall a DB-50 
> connector, but it's been an awfully long time ... Does this 
> description sound familiar to anyone? ----- paul 
The selectric pictured in your link above is a standard Office Products 
(OP) Selectric II.  Some of the selectric terminals where in a enclosure 
that was very similar.  The 2741, 2741 and 1980 I/O units where in a 
similar case but where sunk into a cutout in the desk they where mounted 
in.  The 2970 mod 8 and mod 11 banking terminals where in larger boxy 
enclosures to accommodate extra hardware that was hung on them for 
banking applications.  The 3735 programmable terminal had a Selectric 
I/O II attached that looked just like an OP Selectric except for some 
indicator lights and the big cable exiting out the back.  None of the 
Selectric terminals I worked on had any electronics inside, except arc 
suppression diodes, all of the electronics where housed in an attached 
control unit.

The selectric terminals I worked on where mostly used for banking teller 
station and finance company terminals.  The coding of the data was more 
geared towards the position of the characters on the type ball with 4 
bits for rotate (+1, +1, +2, and -5) and two bits for tilt (+1 and +2) 
and there where also code points allocated to function such as tab, CR + 
LF, space, shift up and shift down.  The relation of the code point to 
the graphic printed depended on the layout of the type ball being used, 
and they where not always the same as the OP selectric.  The type ball 
used by the banks for instance, was laid out so that no two  numbers 
where adjacent to each other on the type ball to lessen the risk of 
printing an incorrect number.


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