[GreenKeys] Model 29 ASR

[Paul Heller]

Jim, that is an outstanding story and I loved reading it. Thank you. 

Paul

> On Aug 17, 2016, at 11:50 AM, Jim Haynes <jhhaynes at earthlink.net> wrote:
> 
> When I was living in the Chicago area I got a couple of machines by way
> of Michigan Bell, but I don't remember how it was arranged.  Probably
> Bert Prall had something to do with it.
> 
> One of these, which I still have, was the Delta Airlines version of the
> 28ASR which I have written about several times in the past.  The other
> I don't remember if I got the whole ASR or just the cabinet, but it was
> one of the "pink" cabinets like Model 29s were made in.  I converted
> that to an 8-level machine using Model 35 parts.  I never did like the
> Model 35 cabinet anyway, and this one I just repainted dark brown and
> put the M35 stuff inside.  (As they say of certain artists, this is when
> I was in my Dark Brown phase.)
> 
> The Model 29 as we know it was not EBCDIC; it was 6-level IBM BCD code,
> a forerunner of EBCDIC to be sure, but only 6-level and upper case only.
> As you have no doubt read it was originally developed as a 6-level
> up/low case machine to replace the Model 20 in Teletypesetter service,
> but apprently nobody wanted to buy any.  (Marketing goof on Teletype's
> part, I guess.  By then hot metal typesetting and Teletypesetter were
> on the way out.)  So it was reworked a little with the IBM BCD code for
> internal Bell System use in data processing.  It was officially called
> the Model 28 Integrated Data Processing set.  Bell didn't want any of them
> to escape into the world at large.  One reason I'm told is that it would
> seem they were playing favorites with IBM and ignoring the other computer
> companies which had slightly different versions of the BCD code.  That
> reason seems bogus, because it would be trivial to modify it for some
> other BCD code.  The more substantial reason was that development of
> ASCII was under way and Bell didn't want anything that would compete with
> ASCII to get out there; they wanted to insure that ASCII would be the one
> standard.  In the meantime the military had Fieldata and I believe that
> was what got used in AUTODIN, though no Fieldata teleprinters were
> released - AUTODIN came with an electronic box that could convert Baudot
> or BCD to its own transmission code.
> 
> EBCDIC was a late-comer in the code development.  During the development
> of ASCII, IBM kept putting up objections that were unacceptable to the
> other companies participating in the standard development.  The main point
> of contention is that Hollerith punched-card code has some gaps in the
> alphabet, with other characters in the gaps.  BCD does also because it
> is really just a simple translation from Hollerith.  And IBM considered
> this so important that they wanted to require any new standard code to
> retain the property.  In this they were wrong, since 512 bytes of memory
> would provide conversion tables between any two 8-level codes and there
> is no real need for a conversion that can be done by trivially simple
> logic.  But IBM has always had a penchant for solving the problems of
> the previous generation of equipment, like they say the generals are
> always fighting the previous war.  The good guys insisted there should be
> no breaks in the alphabet, so that sorting would not be upset by the
> funny characters in the middle.  So ASCII had to have an unbroken series
> of binary numbers representing A through Z.
> 
> IBM surprised everyone by suddenly withdrawing their objections to ASCII,
> and the standard was adopted.  Then IBM announced their new System/360
> computer line and EBCDIC.  EBCDIC has the breaks in the alphabet that
> they wanted.  I assume IBM thought they could use their dominant marketing
> position to establish EBCDIC as a de facto standard and that ASCII would
> then wither away, with only some legacy services such as TWX using it.
> Since the U.S. government required ASCII in all its computer systems
> thenceforth, IBM put an ASCII mode bit into System/360, which made some
> very minor change to the way the system operated, and which was so
> unimportant that it was dropped from System/370.
> 
> I believe what turned the tide in favor of ASCII was the Model 33.  Not
> in its intended role as a TWX terminal, but in the totally new role of
> a computer remote terminal and minicomputer console device.  The
> minicomputer and time-sharing businesses had no need for punched card
> input; and there was nothing to compete with the Model 33 in DataPhone
> service as a remote terminal, nor hardwired to the computer as a local
> console.  What we now call the mainframe computer companies really had
> no means of attaching cheap start-stop terminals to their systems; they
> preferred schemes in which a single terminal adapter polled multiple
> terminals on the same line for messages.
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