Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!ncar!ico!ism780c!news
From: news@ism780c.isc.com (News system)
Newsgroups: comp.arch
Subject: Re: What they did to the 370 (was: Hidden Secrets of POWER Architecture)
Message-ID: <42451@ism780c.isc.com>
Date: 4 May 90 19:01:40 GMT
References: <318@necssd.NEC.COM> <1990May1.163254.476@mentor.com> <616@opus.NMSU.EDU>
Reply-To: marv@ism780.UUCP (Marvin Rubenstein)
Organization: Interactive Systems Corp., Santa Monica CA
Lines: 36

In article <616@opus.NMSU.EDU> jthomas@nmsu.edu (James Thomas) writes:
>In article <1990May1.163254.476@mentor.com> mbutts@mentor.com (Mike Butts) writes:
>
>The IBM 407 "printer" came in two speeds, 100 and 150 lines per minute.
>The upgrade consisted of removing one relay.  (We stuck a folded card {80
>column of course :-} in except when we called the CE :-)

The 407 was more than a printer.  It was called an accounting machine.  It
had an adder and it could do some rather complex operations.  After the
introduction of the 1401 (a stored program computer) IBM 'introduced' the
series 50 line of unit record equipment.  This line was simply a slowed down
version of their previous line.  It did extend the economic life of the
equipment.

>The IBM 1622 card reader came in 600 and 1000 (maybe?  that's getting a bit
>foggy :-) card per minute versions.  The pulley did not have both sizes, it
>had to be changed for the upgrade.

The 1620 reader/punch came in two speeds 250/125 and 500/250 (reader/punch
speeds).  The machine we bought had the lower speed reader/punch.   We
discovered that the pulleys had a variable diameter that could be changed by
adjusting screws.  We changed the pulleys to the higher speed.  But the
machine was not reliable at the higher speed.  The reason was that the
machine had cam actuated circuit breakers used for timing.  At the higher
speed the breakers developed "valve float".  In order to make the machine
work, we had to replace the circuit breakers with ones that had stiffer
springs.  Still, the cost of our do it yourself upgrade was much less than
IBM's price.

Another bit of historical trivia.  The first IBM machine we installed was
an 080 card sorter.  It was supposed to move cards at the rate of 600/min.
We were having frequent jams.  I put a stroboscope on the machine and found
that is actual rate was more like 800/min.  The cure: adjust the pully
diameter.

    Marv Rubinstein -- Historian?