Tony Firshman writes: > > I once had an old mechanical calculating > >machine, given to me by my grandfather to play with when the bank he worked > >for upgraded to electro-mechanical ones. I later used it for my homework, > >the only kid at school with access to a calculator, (something I had to keep > >secret as my teacher would not have approved.) Division was quite a > >convoluted affair involving multiple subtractions and shifts. I used that > >same algorithm later in my assembler longword division routine. > > I am your grandfather it seems, as these were, other than slide rules, > the only mechanical things we had at Imperial College in the 60s.
Unlikely, but Id be happy to adopt you as mines gone missing ;) > Even transistors were new then (8-)# > > Was yours the one you had to turn a handle - one way for addition and > the other for subtraction, and shift manually? Exactly! A good athlete could squeeze between 0.1 and 0.4 flops out of one of those. A proficient abacus user would beat that hands down, though. > Using methods like that, as you say, give one a good feel for the > mechanics of programming. I believe the algorithms used today are fundamentally the same. > The same could be said for the UK101 (almost all discrete 74X TTLs) and > computer hardware. > > Sinclair ULAs don't give any good feel of what the poor old computer is > actually _doing_ at the basic level. > > Even the system clock on the UK101 was divided by 7404s! Developments have been incredible since then! I wonder if we are entering a phase of diminishing returns and consolidation or whether were going to see changes on that scale for the next 40 years. Per
