Drum vs. Core

Initially most were printing terminals with lights inside, not Teletypes, can't remember the maker's name. <<< Probably Trend There was also just two CRT terminals, on which you typed a load of lines and told the computer to read it. <<< Could well have been "genuine" ICL block-mode terminals Do you think the drum got kicked out when we went over to the 4S? <<< Probably when they went to a dual '4S configuration - they really tried to have a resilient system - each 4S had its own motor-generator set and _all_ the peripherals were "Y"-switched. The flaw in the configuration only appeared when the power-supply to the Y switches failed :-( [actually, they could have kept running even then, but the Engineers naturally refused to work on that without turning the power off] Was it really that slow! We really put up with a lot back then. <<< I've still got the timings from the acceptance benchmarks and have run the same benchmarks on many machines since. ** the most important of these benchmarks was the original "Whetstone" benchmark - Fortran carefully crafted to not be optimisable*1 - in fact in ran slower on the optimising compiler than on the standard one. *1 eventually (20 years later) compiler technology did manage to optimise away much of the code. Interesting. Maybe it was like my school maths teachers who forced us to use fountain pens instead of ball points because it slowed us down so we thought more about what we were doing and so made less mistakes. <<< No - it was that the engineers _knew_ the ciruit diagram of the processor and "000 3 100" was more meaningful to them than "LDX 3 base", say. Very difficult. I had always assumed the executive lived at a fixed position in memory. Maybe it used relativisers, 1300 style, where every instruction could specify what block start address should be added to it, but maybe that would slow down loading the overlays too much. <<< The fixed part of Exec loaded at 0 - but the overlays could be on any 64-word boundary.(actually, probably 128 word - but the code would have worked on a 54 word boundary) I wonder if any of the concepts in the 1302 executive got re- used on 1900. <<< I don't know, but I doubt it - wasn't the 1300 series a Stevenage design, while the earliest 1900s came from West Gorton (well, actually the earliest 1900 was the Canadian FP6000). Different parts of ICL had very much a "not invented here" attitude and the previous West Gorton product was Atlas. Maybe ICL had been bumping up the maintenance charges for old kit they really did not want to support any more. <<< That wouldn't have affected us - we had our own engineers and did our own maintenance. I suspect we were the only none-MOD site in that position. I wish I had saved more of the engineering documentation - I probably have enough to make a very close approximation on a FPGA, but there doesn't seem to be a survivng operators Exec for a 1900, only George 3 stuff. Andy No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.476 / Virus Database: 269.9.14/883 - Release Date: 01/07/2007 12:19