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From: res@ihuxn.UUCP (Rich Strebendt)
Newsgroups: net.misc
Subject: Re: Nearly Prehistoric Computers
Message-ID: <548@ihuxn.UUCP>
Date: Fri, 10-Feb-84 15:51:15 EST
Article-I.D.: ihuxn.548
Posted: Fri Feb 10 15:51:15 1984
Date-Received: Sat, 11-Feb-84 08:51:38 EST
References: <584@ihuxq.UUCP> <510@dalcs.UUCP>
Organization: AT&T Bell Labs, Naperville, IL
Lines: 69

>  	The machine I learned to program on was an "LGP-30" with 4K
>  (24 bit) words of drum memory. The only language available was machine
>  language (not assembler) though it was easy to learn as there were
>  only 16 machine language instructions. The hardest part was learning
>  the (now lost) art of optimising(sp?) drum accesses (NOT easy). I/O
>  consisted of a terminal like thing called (I think) a flexowriter, and
>  a "high speed" paper tape reader and punch (also many buttons & lights).


FANTASTIC --- someone else that worked with this fun machine!

I once found a flier by an outfit that reconditioned these machines
then sold them.  A few quotes might be interesting/entertaining to the
"younger generation" that has become jaded with computer power that
fits on a desk-top.

"Control Data [ours had a Royal-McBee nameplate] LGP-30 Low Cost, Desk
Size Computer

"The LGP-30 is compact and can be installed anywhere without special
preparation.  The computer is mounted on casters, can be freely moved
from place to place, and is simply plugged into a convenient grounded
outlet.

"The LGP-30 is a stored program binary computer with a 4,096 word
memory of 32 bits per word.  It is the size of a standard office desk.
The powerful but compact repertoire of 16 single-address instructions
includes all basic arithmetic operations and logical decisions
necessary to provide a broad capability, including alphanumeric
input-output. ...  Standard input-output equipment consists of a
typewriter [actually, a Frieden Flexowriter] with standard keyboard,
paper tape punch and paper tape reader. ... Optionally available is a
high speed, 200 character-per-second photoelectric paper tape reader
that completely loads memory in only 5 minutes.

"Operation Times
	Access: 6 milliseconds minimum, 15 milliseconds maximum
	Transfer: 1 millisecond minimum, 15 milliseconds maximum
	Addition/Subtraction: 0.26 milliseconds, excluding access
	Multiplication/Division: 15 milliseconds, excluding access
Physical Description
	Size: 26" deep by 33" high by 44" long, excluding typewriter
	and shelf
	Weight: 800 pounds
	Mounting: on sturdy casters
Power Requirements
	Full: 1500 watts from 115-volt, single phase, 60-cycle supply
	Standby: 350 watts"

This was taken from a flier or an advertisement copyrighted in 1968 by
Mutual Computer Systems of Culver City, California.  (No, I have not
attempted to obtain permission to quote this material ... Is this
company still in business?)

Not mentioned in this description is the programming language that I
used to program it.  It was called the "24.2 Floating Point
Interpretive System" and was about -><- that far above machine coding.
The instructions consisted of a single character opcode and a 4 digit
address, where the address 0000 completely changed the meaning of the
opcode.  For example:  s2420 meant subtract the contents of location
2420 from the accumulator (which was a circulating track on the drum).
The instruction s0000 meant take the sine function of the contents of
the accumulator.  It really was a fun machine to work with ... we
discovered that the Blackjack program was cheating because it took it
several seconds to search the deck for an Ace ... a perceptable delay
in playing its next card!

					Rich Strebendt
					...!ihnp4!ihuxn!res