🚀 go-pugleaf

For Mike:

lwin> From: lwi...@bbs.cpcn.com (lwin)
lwin> Newsgroups: alt.folklore.computers
lwin> Subject: Re: IBM 350/1405/1301/1302 disks
lwin> Date: 26 May 2000 02:08:37 GMT

Jim > (Mike also thinks the disk was called the 305 - the same as the system
Jim > name.)

lwin> 305 and 350.

lwin> I forget which, but the disk itself had one name, and the system it was
lwin> a part of it had the other.

lwin> Note that this system, while technically a computer with a programming
lwin> language, had all of _80_ characters of core memory!  It was mostly
lwin> "programmed" by wiring plugboards for its various peripheral devices.

	I dimly recall the core memory being 100 characters (we used to
have a stack from a 305 in a plexiglass box as a "teaching aid"), but
it was not the main memory anyway. It was the "sector buffer". The main
memory of a 305 was a drum. If you think for a while about the problem
of transfering data between a spinning disk and a spinning drum, the need
for either a sector buffer or one heckuva sophisticated set of spindle-
motor controllers becomes evident :-)

	The 305 was a stored-program computer, but there were indeed
quite a few plugboards. One of the most bizarre was the one which
had hubs which emitted a pulse when a "branch" instruction with a
particular suffix was executed. That pulse could be routed through
various tests and then into a portion of the plugboard which
essentially jammed the program counter.

	 _Real_ 305 programmers, please bear with me, or better yet,
correct me. My knowledge of the 305 comes from reading a manual
that one of the older guys left around at a buddy's shop. Anyway,
you would code something like "B*", and a pulse would come whipping
out of the '*' hole on the plugboard when it executed. You ran wires
from there through whatever condition you meant to test, such as
"overflow", "printer on channel 9", "console swith A set", etc,
in pretty much any combination. Then used a splitter to send the
resulting pulse into holes for the various values of the various
digits of the "next pc". Wild. I'd love to get a more accurate
description, because I'd hate to think _I_ was the only one who
remembered...


					Mike
| alb...@agames.com, speaking only for myself