[GreenKeys] Xerox used teletype model 35 but not ASCII

[Jim Haynes]

On Tue, 31 Mar 2015, Tom Watson wrote:

> The question remains, why a Teletype?  I suspect that it was the easiest
> device.  They couldn't use (arguably better) Selectric mechanism as it
> was produced by their competitor which would be bad karma.  The only
> thing that might be close was a Friden Flexowriter which was being
> phased out as I remember.  So, Teletype it was, modified but it worked.
>
Flexowriter was a lot more costly than a Teletype.  (and normally included 
paper tape that you probably didn't need in a computer console)  It was 
based mechanically on the older IBM electric typewriter.  And the 
Selectric was less rugged (but would do upper/lower case) and considerably 
more complicated to interface with.

UNIVAC also used Teletype printers as console devices, but with an
electronic keyboard.  I don't know if they used ASCII models or modified
for some other code.

A forerunner of the Model 35 was sometimes called Model 29, and was
designed for 6-bit code.  These were, I'm told, originally intended
to replace the Model 20 printers in Teletypesetter service, but
apparently nobody ordered any.  So they were recast to use IBM BCD
code (6-bit) and supposedly for use only internal to the Bell System.
AT&T didn't want to support an IBM code and be accused of favoritism
to IBM, although all the other computer companies used variatings of
BCD and probably could have been accomodated just by slight changes
to the type box.

And then Burroughs used a modified Model 33 as the console device on
their mainframe B5500 model.  And most of the minicomputer companies
used Teletype console devices.  Hard to beat a Model 33 ASR for the
price, compared with a Flexowriter.