ENIAC programming Was: release dates of early microcomputer operating systems, incl. Intel ISIS

Noel Chiappa jnc at mercury.lcs.mit.edu
Wed Sep 16 16:06:29 CDT 2015

    > From: Al Kossow

    >> the machine had to be configured (via connecting up computing units
    >> with cables)

    > In 1947 ENIAC was modifed at BRL to be a stored program computer.

Well, I did say "in the original ENIAC usage" it had to be configured by
plugging! I was aware of the later conversion.

    > http://dl.acm.org/citation.cfm?id=1339839

    Crispin Rope, "ENIAC as a Stored-Program Computer: A New Look at the Old
	Records", IEEE Annals of the History of Computing, Vol. 29 No. 4,
	October 2007

Thanks for that pointer. I couldn't get access to that paper (it's behind a
paypal I don't have the ability to pierce - I would be grateful if someone
could send me a copy), but in looking for it online, I did find the very
    Thomas Haigh, Mark Priestley, Crispin Rope, "Engineering 'The Miracle of
	the ENIAC'", IEEE Annals of the History of Computing, Vol. 36, No. 2,
	April-June 2014

which includes the same author, and is later, so hopefully more definitive.

It's quite interesting: according to that, the conversion of ENIAC to a
'stored program' configuration, after a period of about a year of discussion
and planning, took place starting around March, 1948, and the first problem
was run using it in April, 1948 - and it cites a lot of contemporary
documents to that effect.

(As the article points out, this contradicts the long-and-widely-held
impression, from a statement in Goldstine's book - and if anyone knew, it
should have been him! - that gave the date of that as September, 1948.)

Anyway, the new, earlier date is of course is very shortly before the Baby
ran _its_ first program, in June, 1948. So there is a rather interesting
question as to which 'computer' ran first. I'd always gathered it was the
Baby, but this new data may overturn that.

It is true that the 'program ENIAC' (to invent a term to differentiate that
stage of the machine from the earliest configurations, which used the cabling
method) did not store its program in the same read-write memory as data, as
the Baby did, instead storing it in 'EPROM' (switches). However, I don't
consider that very important; nobody says that a machine running out of PROM
isn't a computer!

The important thing is that it's a program, with things like subroutine calls
from different locations, address modification for data access, etc, and the
'program ENIAC' apparently had all that (see the list at the bottom of page 51
in the article). So it's likely indeed be the 'first computer'.


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