Seymour, (Hope that's ok) Many early machines were serial. The Manchester SSEM and it successors the Manchester MK1 and Ferrante MK1* were all serial, as was the Ferranti Pegasus. The machine at Cambridge(UK), EDSAC was also serial. Not sure about ENIAC but wasn't that a decimal machine as well?. EDVAC was also serial.
For example, the Manchester Baby was a 32 bit machine with three Williams tubes, Main Store (32 x 32) Accumulator (1 x 32) Control Store (2 x 32) To build that as a parallel machine would have needed 96 Williams tubes, I believe that even the IBM 701 only had 72..... .. so I think if you are building a machine with storage that is inherently serial at some level, so Williams Tubes, Delay Lines or even a drum it makes sense to build a serial machine. Once you start using core storage and transistors the mathematics change and parallel becomes much more attractive... Dave > -----Original Message----- > From: IBM Mainframe Assembler List <[email protected]> > On Behalf Of Seymour J Metz > Sent: 17 June 2022 09:05 > To: [email protected] > Subject: Re: When did logical instructions appear? > > FSVO serial. The early electronic machines that I'm aware of were parallel. > > FWIW, there were papers claiming that 1s' complement was simpler. I believe > that the tradeoffs vary depending on the technology used. > > > -- > Shmuel (Seymour J.) Metz > http://mason.gmu.edu/~smetz3 > > ________________________________________ > From: IBM Mainframe Assembler List [[email protected]] > on behalf of Robin Vowels [[email protected]] > Sent: Friday, June 17, 2022 2:40 AM > To: [email protected] > Subject: Re: When did logical instructions appear? > > ----- Original Message ----- > From: "Paul Gilmartin" <00000014e0e4a59b-dmarc- > [email protected]> > To: <[email protected]> > Sent: Friday, June 17, 2022 7:20 AM > Subject: Re: When did logical instructions appear? > > > > On Jun 16, 2022, at 10:43:36, Robin Vowels wrote: > >> > >> Computers have had instructions for signed and unsigned binary since > >> at least 1951. When negative values are expressed using twos > >> complement notation, ordinary addition will give the same result > >> whether the operation is signed or unsigned. > >> > > It puzzles me that some of the oldest computers employed sign- > > magnitude notation when 2's (1's, 10's) complement would have needed > > fewer gates and fewer clock cycles. > > For a serial machine (and most of them were in the early days), twos > complement was the simplest. It needed only one cycle for add and subtract. > Even subtract (complement and add one) was done in a single cycle, "on the fly". > It was unnecessary to add the one; complement commencing after the first non- > zero bit. > > Ones complement was a PITA, because a carry out of the high end required a 1 > to be added in the next cycle. This was no good at all for array machines such as > Pilot ACE, DEUCE, and ACE, because the word just summed would not have been > around to add the final "1" produced by the carry out -- the arithmetic unit > already working on summing (or subtracting) the next pair of words. > > > Perhaps an accommodation to the engineers' habits. > > --- > This email has been checked for viruses by Avast antivirus software. > https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.av > ast.com%2Fantivirus&data=05%7C01%7Csmetz3%40gmu.edu%7Cf84bb17 > cd7eb400175a608da502c27ae%7C9e857255df574c47a0c00546460380cb%7C0 > %7C0%7C637910447840045536%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4 > wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C > %7C%7C&sdata=o2r1kMl7%2F4ORpMDX%2Br1beF%2F271qN32kc3tBcqz6 > H7l0%3D&reserved=0
