> -----Original Message----- > From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Noel > Chiappa > Sent: 17 September 2015 13:39 > 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: Dave Wade > > > Crispin Rope concentrates on the power of ENIAC and its usefulness > > Which is why you should look at the longer, later article: > > http://eniacinaction.com/wp- > content/uploads/2014/02/EngineeringTheMiracleoftheENIAC-scanned.pdf > Thanks Noel, I will have a browse of that...
> in particular the part I pointed out (bottom right corner of pg. 51), which talks > about all the things that can be found in that early ENIAC code, e.g. > subroutine calls with storage of return point, etc. > > I am far less interested in the comparison with other machines (in that > article) than I am with the enumeration of what the 'program ENIAC' _itself_ > could do - which seems to have been quite a lot. > > > to me a "computer" without self-modifying code is a programmable > > calculator even if it has index registers... > > So a modern Harvard-architecture machine (e.g. AMD29K) with only ROM on > the instruction bus is a programmable calculator? AMD29K isn't "Modern", but when used like that it's a programmable calculator, a very sophisticated one yes...... ... If you have to use another external mechanism to arbitrarily change the program, then it's a calculator..... .. So a PIC chip for example..... Where It gets grey is that a Turing machine gets round this by assuming the tape has infinite length. I think (but am not sure) is that in effect whilst you can't have self modifying code you have enough storage for all possible programs... > > It's precisely that hypothetical which leads me to conclude that the fact that > the 'program ENIAC' only had ROM for its code (actually, technically, that's > quite not true - it could execute programs stored on cards, too) is not that > important; I think the thing to look at is what its programs could contain I think the important things end up being hypothetical, Its more WHY was it designed so its programs COULD contain what they could contain.. > > Noel Dave
