Re: OT : on the trail of the original "Real Programmer"

["Michael J. Mahon" <mjmahon@aol.com>]

Jonno Downes wrote:
> On Sunday, March 27, 2011 4:21:05 AM UTC+11, Michael J. Mahon wrote:
>
> > The IBM 650 was perhaps the best known of these computers.  SOAP
> > (Symbolic Optimizing Assembly Programmer) was its corresponding
> > assembler.
>
> I found a video of a 650 in action. I hadn't realised how noisy they where, what with the whirring of the motor and the clacking of the card reader.

With most "mainframe" (room-sized) computers, the noise was pretty
much a toss-up between the card equipment, the cooling fans, and
the air conditioning equipment.

Drums and disk drives added their own distinctive whines.

Don Knuth tells a wonderful story about how, when he was tending a
night run of Carnegie Mellon's 650 while studying, he became slowly
aware of something changing...  The pitch of the computer's drum
motor was slowly decreasing, and he watched as, after a few minutes,
the console lights began to flicker perceptibly slower.  Eventually,
the computer halted with a check (the decimal data was coded with a
2-out-of-5 code, and when any digit failed to have 2 bits set, a
machine check stop occurred).

It turned out that the drum motor had failed, and the drum gradually
slowed to a stop.  Since the 650 was clocked from a clock track recorded
on the drum, the whole machine slowed down with it, and its excellent
margins allowed it to continue to operate correctly until the drum
was turning significantly below its normal speed.

-michael

NadaNet 3.1 for Apple II parallel computing!
Home page:  http://home.comcast.net/~mjmahon/

"The wastebasket is our most important design
tool--and it's seriously underused."