The first PC circa 1965 1298

CBFalconer

Very interesting. I'm somewhat familiar with the Monroe-Litton calculators of around that time (I have a couple that I occasionally fire up) and I've got a HP-9100A too, the DAC-512 appears to have substantially more programmability in a much smaller package than anything that came out for several years afterward.

The Monroe-Litton units I have are all printing units, and they have a separate "electronics box" that drives the desktop printer-keyboard.

The DAC-512 seems to be aimed at scientific-engineering use, kind-of like the early HP desktop calculators (9100, 9100A, 9100B), but the DAC-512 seems to lack any trig-exponent-scientific functions built-in. Did the user have to key in the subroutines for these functions whenever they wanted to use them? How big were they? (i.e. could you have exponent, cos, and sqrt all resident at the same time without using up all the memory?)

Obviously the Monroe-Litton calculators I have were aimed at the business market (fixed-point, no scientific functions). The DAC-512 seems to be conceptually halfway between what became the "standard" HP scientific interface and the business programmables. The DAC-512 seems to have better indirect addressing features than HP's of that era, making them probably better suited for small matrix operations of variable size. (As a practical matter, for a fixed matrix size the HP's were usable if maybe a little awkward.)

It's a little bit like the DAC-512 was really designed to be a configurable toolkit. It doesn't have the swiss army knife array of scientific functions that the later HP's had built-in, but it could be programmed to do them if they were necessary.

Tim.