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Path: utzoo!linus!philabs!seismo!rlgvax!cvl!umcp-cs!fred
From: fred@umcp-cs.UUCP
Newsgroups: net.social
Subject: Re: My first time (working with a computer)
Message-ID: <2566@umcp-cs.UUCP>
Date: Tue, 13-Sep-83 20:09:35 EDT
Article-I.D.: umcp-cs.2566
Posted: Tue Sep 13 20:09:35 1983
Date-Received: Wed, 14-Sep-83 04:50:08 EDT
References: <521@ritcv.UUCP>
Organization: Univ. of Maryland, Computer Science Dept.
Lines: 49

Ok, I'll put in my two cents worth.

The first computer I worked with (back in 1969 or so) was a Burroughs
model something-or-other which was built into a large desk. It was
a vacuum tube machine with two registers and 120 words of main
(i.e.: drum) memory. It was programmed by sticking little metal
pins into plugboards, each of which contained 15 instructions. Each
instruction consisted of three pins: one for the opcode and two to
specify the operand. The boards looked sort of like this:

      (operation)     (1st two digits)       (last digit)
    ____________________________________________________
    |   ASMDPKLH  0 1 2 3 4 5 6 7 8 9 10 11  0123456789|
    | 1 .....O..  . O . . . . . . . .  .  .  .O........|
    | 2 .O......  . . O . . . . . . .  .  .  O.........|
    | 3 .....O..  . O . . . . . . . .  .  .  .O........|
    | 4 O.......  . . O . . . . . . .  .  .  O.........|
    | 5 ....O...  . O . . . . . . . .  .  .  .O........|
    | 6 .......O  O . . . . . . . . .  .  .  O.........|
    | 7 ........  . . . . . . . . . .  .  .  ..........|
    |			.                              |
			.
			.

The machine could be loaded with ten of these boards at a time.
There was a series of neon bulbs which lit to indicate which board,
and which instruction on that board, was being executed. The
program-counter was mechanical, and slow enough that you could hear
each instruction being executed, accompanied by the moving neon
sequence lights. I'm convinced that that's where the term ``number
crunching'' comes from, 'cause that's EXACTLY what it sounded like
when a loop was being executed. You can get the same effect by
running your fingernail down the teeth of a comb. One of the weird
quirks of the machine was that the instruction ``M n'' would multiply
the contents of register B with memory location n, leaving the
result in register A, but ``D n'' would divide the contents of
register A by the contents of register B and store the result in
memory word n. There was no such asymmetry between the add and
subtract instructions.

					Fred Blonder
					harpo!seismo!umcp-cs!fred

P.S.: In case you're wondering: The program on the plugboard is:
	(1) read a number from the keyboard, (2) store it in word 20,
	(3) read another number, (4) add word 20 to it, (5) print result,
	(6) halt

P.P.S.: How many of you ever owned an Edmund Scientific Digi-Comp I?