> -----Original Message----- > From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Noel > Chiappa > Sent: 16 September 2015 22:06 > To: cctalk@classiccmp.org > Cc: j...@mercury.lcs.mit.edu > Subject: Re: ENIAC programming Was: release dates of early microcomputer > operating systems, incl. Intel ISIS > > > 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 struggled to get it out of the University Library system. > I did find the very > similar: > > 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. > I believe that its generally accepted that is true. > 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! It is notable that in order to solve all problems, a computer must permit self modifying code. In the above article Crispin notes that ENIAC was succeeded by the IBM 701 and then omits the fact that the 701 used the Williams tubes from the Baby as its main store, so clearly both machines had a non-significant influence on early computing. Without Williams and ENIAC there would have been no IBM701... > > 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'. > > Noel What is and isn't a computer is always open to debate. The Manchester SSEM or Baby is I would say the simplest thing that you could call a computer. I could explain how to program the Baby to almost any one on this list. It has seven instructions, so in a 32 bit word, a 5 bit address and a 3 bit op code. Crispin Rope concentrates on the power of ENIAC and its usefulness, neither of which can be argued with, but to me a "computer" without self-modifying code is a programmable calculator even if it has index registers... If you want to rate a computer by the work it did ENIAC was far more useful, but the SSEM was never intended to be a "Useful" computer. It was a testbed for the Williams Tube. ... on the other hand whilst both added to our knowledge of computing in the longer term neither were IMHO especially influential going forward. Self-Modifying code became the norm, and Williams Tubes were rapidly superseded by core... >From what I have seen the UK was slow to move onto Core store, probably because IBM bought the patents, so whilst the IBM 704 was already using Core in 1954 the Ferranti Pegasus from 1956 went back to using Nickle Delay Lines and a Drum for "Main Store" although IMHO the Delay Lines were really main store, from what I remember all code must be in the delay lines. The LEO (Lyons Electronic Office) also used Mercury Delay Lines.... Dave Wade
