LGP-30
It weighed about 800 pounds (360 kg),[5] and was mounted on sturdy casters which facilitated moving the unit.
The primary design consultant for the Librascope computer was Stan Frankel, a Manhattan Project veteran and one of the first programmers of ENIAC.
The number of vacuum tubes was minimized by using solid-state diode logic, a bit-serial architecture[7] and multiple use of each of the 15 flip-flops.
In addition to power regulation, the computer also contained circuitry for a warm-up stage, which minimized thermal shock to the tubes to ensure longer life.
The computer contained a cooling fan which directed filtered air through ducts to the tubes and diodes, to extend component life and ensure proper operation.
Otherwise, each instruction would wait a complete drum (or disk) revolution each time a data reference was made.
To further reduce costs, the traditional front panel lights showing internal registers were absent.
Horizontal and vertical size controls let the operator adjust the display to match a plastic overlay engraved with the bit numbers.
Unlike other computers of its day, internal data was represented in hexadecimal instead of octal, but being a very inexpensive machine it used the physical typewriter keys that correspond to positions 10 to 15 in the type basket for the six non-decimal characters (as opposed to the now normal A – F) to represent those values, resulting in 0 – 9 f g j k q w, which was remembered using the phrase "FiberGlass Javelins Kill Quite Well".
Every token had to be delimited by an apostrophe, making it hard to read and even harder to prepare tapes:[9] Dartmouth College developed two implementations of ALGOL 60 for the LGP-30.
SCALP, a Self Contained Algol Processor, was a one-pass system for a small subset of ALGOL (no blocks other than the entire program), no procedure declarations, conditional statements but no conditional expressions, no constructs other than while in a for statement, no nested switch declarations (nested calls are permitted), and no boolean variables and operators.
[10] DICTATOR is a painful acronym for DODCO Interpretive Code for Three Address with Technical Optimum Range.
A bit more than half the total LGP-30 memory is used by the interpreter; it takes about 30 minutes to load the paper tape via the Flexowriter.
This process was repeated, maybe six to eight times, and a rhythm was developed: The operator then removed the bootstrap tape, snapped in the tape containing the regular loader, carefully arranging it so it would not jam, and pressed a few more buttons to start up the bootstrap program.
Each block began with a starting address so the tape could be rewound and retried if an error occurred.
His discovery that massive differences in forecast could derive from tiny differences in initial data led to him coining the terms strange attractor and butterfly effect, core concepts in chaos theory.
[23] A software simulation of the LGP-30 and LGP-21 are supported by SIMH, a free and open source, multi-platform multi-system emulator.
