[GreenKeys] Re: GreenKeys Digest, Vol 16, Issue 21

[Randy and Sherry Guttery]

Tim McNerney
> Subject:  "electrifying" Selectrics

> I have poked around the Web looking for sites that talk about converting 
> an IBM Selectric to a printing terminal.  I guess that's just not 
> popular anymore.  Have any GreenKeyers tried it.  I can't imagine it is 
> exceptionally difficult, presumably just a small number of solenoids, 
> carefully mounted in the right place...

Yes - I've both worked on commercially produced IBMs converted for 
computer I/O use by the military - and I converted quite a few in the 
early 80's for use on micros as word quality printers.

Yes - there it takes several solenoids (usually the type that look like 
a relay but without contacts on the armature)- to "pull" the selector 
bails - and switches mounted in tandem to "read" the selector bails - 
plus one switch on the operational shaft to tell the electronics when to 
"read" the switches (some of the less reliable ones used a switch on the 
cycle bail). The selector bails run under the keyboard and "read" the 
"encoding" of each keylever. There are six selector bails (these select 
which character is typed) the cycle bail (which initiates a type 
cycles); then you need solenoids for: Space, shift and return at a 
minimum; most also have solenoids to operate tab, backspace and line 
feed (independent of return which also does a line feed) and I've seen 
some with express back (return without line feed), bell and half-space.

The early ones I worked with were truly heavy duty - designed to 
interface with several navigational systems aboard Boomers (SSBNs - 
Fleet Ballistic Nuclear Submarines).  My particular specialty was SINS 
(Ships Inertial Navigation System) and the IBM selectrics were "our" 
domain (I.E. we had to maintain the things). These were converted by/for 
Autonetics - and in typical military overkill style - were way 
overbuilt. Of course the up-side is that they were indeed very reliable. 
The down-side was that they were almost twice the size of a "normal" 
unit - with all the "stuff" underneath - they had an "extended" base. 
You can see a couple of them here:

http://www.mississippi.net/~comcents/selectrics.jpg

There is one either side of the guy sitting there (and no, that's not 
me- we were at the equator on the international date line - getting 
ready for the "Polywog Revolt" part of the Golden Shellback initiation 
Ceremonies). Anyway - sorry the dust covers were in place - but the 
upper half were "standard" anyway. There were no electronic in the units 
themselves - just solenoids and switches. The massive "mounts" contained 
the logic and driver electronics. The one on the left was set up for use 
on a SINS Mk2 Mod 4 (Verdan computer) SINS; the one on the right - a 
more modern Mk2 Mod6 (Mardan computer - which you can just see part of 
in the very right of the photo). This was December 16 1972 aboard USS 
Proteus AS-19 - a submarine tender which was on it's way back to Guam 
(via Australia) to service Boomers.


Later - (early 80's) when micro computers came about - there were some 
"conversion" kits made by various manufacturers that could convert any 
standard selectric into an output (we didn't try to use the keyboard). 
The one we sold / installed / and serviced (though I only recall one 
repair - and that was caused by a pinched wire caused when the customer 
wasn't careful putting the cover back on) had a small aluminum box with 
the electronics in it (including serial and parallel inputs) a long 
ribbon cable connected it to the Selectric. It had smaller solenoids 
than the military version - but it didn't try to 'push' the thing all 
that fast either - and it worked pretty well.

The problem with such these days would be parts - tilt and rotate tapes 
stretch - and while there are built-in compenstators - running one that 
hard (under computer control) wears these pretty fast - and they have to 
be replaced - while not brain surgery - not an easy / quick task either. 
   Then there are other parts that would wear -- like the kearfot (sp?) 
clutches, for instance...  those are probably getting hard to get - and 
in a machine that's already old...  maintenance might be a real pain.

As interesting a machine as they are - I'd still much rather have - play 
with a 28 any day!

best regards...
-- 
randy guttery

A Tender Tale - a page dedicated to those Ships and Crews
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