Librascope General Purpose | 1956

LGP-30

 


The LGP-30, which stands for Librascope General Purpose and later Librascope General Precision, is an early off-the-shelf computer manufactured by the Librascope company in Glendale, California, a division of General Precision Inc. It was first produced in 1956, with a retail price of $47,000, equivalent to approximately $530,000 in 2023.

Commonly referred to as a desk computer, the LGP-30 measured 33 by 44 by 26 inches and weighed about 800 pounds. It was designed by Stan Frankel, a veteran of the Manhattan Project, who aimed to create a usable computer with minimal hardware. The computer featured a single address instruction set with only 16 commands and utilized magnetic drum memory for its main memory.

The LGP-30 was a binary, 31-bit word computer with a 4096-word drum memory. Standard inputs included the Flexowriter keyboard and paper tape, while the output was through a Flexowriter printer. It contained 113 electronic tubes and 1450 diodes, mounted on 34 pluggable circuit cards.

Operating at 1500 watts, the LGP-30 could plug into any standard 115-volt power line and included voltage regulation for powerline variations. It also featured a cooling fan to extend the life of its components.

The computer's design allowed for operand-location optimization by interleaving logical addresses on the drum, which improved access times. The LGP-30 had a unique built-in multiplication feature and used an oscilloscope for displaying internal registers instead of traditional lights.

Specifications include a word length of 31 bits, a clock rate of 120 kHz, and a multiplication or division time of 17 ms. The LGP-30 was one of the first desk-sized computers, achieving popularity with around 320 to 493 units sold, including one to Dartmouth College, where students implemented Dartmouth ALGOL 30 and DOPE on the machine.

The instruction set consists of 16 instructions, each occupying a 31-bit word, with the order bits in positions 12 through 15 and the address bits in positions 18 through 29. Some instructions do not use an address, typically entering 0000 in such cases.

이 블로그의 인기 게시물

콜러서스 컴퓨터 [Colossus computer | December 1943]

NTDS [Naval Tactical Data System | 1961]

에니악 [ENIAC | December 10, 1945]