Re: Computer History Museum
- From: chrismason@xxxxxxxxxxxx (Chris Mason)
- Date: 24 Dec 2008 07:17:40 -0800
Tom
It doesn't inspire much confidence in the curatorship of the museum that they
picked on the register size of the 360 Model 20 as an indication of the
capability of the range. You don't "start at" a register size for a range of
computing machines. Assuming that the range will all be capable of running
the same software, you had jolly well better have the same register size for all
machines in the range.
What this ridiculous comment hides is that the 360 Model 20 was sufficient of
a variation on the common features of the remainder of the range to be
treated quite separately. It had its own operating system which was not
intended for use on other machines in the range and vice versa.
Indeed in a relatively short period of time, the 360 Model 20 transmogrified
into the range of machines which we know today as the iSeries - follow the
rather special programming language Report Program Generator (RPG) using
which the grist was created for the Model 20 mill and which was supposed to
help codify the wire plugs of the unit record machines the Model 20 was
designed to replace.
I once did some programming on the Model 20 - excluding the Model 20 hands-
on class where I wrote RPG programs - obviously! The exercise was to
examine binary synchronous communications (BSC) logic and, incidentally, how
to program a "multiple wait" on the Model 20 "hardware" while bypassing the
operating system. Thus card reading, packing the data and sending were
logically separate "tasks" and receiving data, unpacking the data and printing
were also separate tasks. I must have got quite familiar with those 16-bit
registers at the time!
I happen to know rather precisely when I performed this exercise because of
an important event which happened as I was desk-checking the BSC logic. It
was March 1971. I'm pretty sure that the department which supported the
Model 20 were really much more interested in supporting the System/3 so that
date indicates approximately when the "transmogrification" occurred.
Incidentally, the partner programs were written in BATS (over BTAM) and ran
on a "real" 360 - or maybe 370 by then.
Another "incidentally": the Model 25, introduced rather later than the original
models, was also a "real" 360.
If the author of the text to accompany the 360 machines in the museum
insisted on mentioning the register size - somewhat pointless really unless to
compare with some other machine range perhaps, he/she would be obliged to
mention that a 32-bit register size applied to the whole range - excluding the
Model 20 with its special characteristics such as of having 16-bit registers.[1]
As for memory size, I suppose the Model 20 may have managed with a size of
4K and still managed to support the operating system. As for "real" 360
machines, the Model 30 probably had the option to be limited to 4K but the
smallest operating system I ever worked with itself required 4K. Thus a
sensible minimum storage size is likely to have started as 8K.
Nevertheless, I have the very faintest memory - of a manager suggesting we
use them! - of some I/O routines being available from IBM which presumably
would allow the practical use of a 4K machine. In order to support a 1287 on
an 8K Model 30 without disks, it was either work with these I/O routines or
adapt a 4K card-based operating system (the 1231 Support Package - or
some such name) to handle the special requirements of the 1287 optical
character (hand-written numbers) reader. I chose the latter, eventually it
worked and a salesman's rear-end was saved!
Chris Mason
[1] Actually there may be other exceptions. The 360 Model 44 for example
was also a special machine somehow specifically designed to support "science
and engineering" (Fortran) as I recall.
On Wed, 24 Dec 2008 06:48:58 -0600, Kelman, Tom
<Thomas.Kelman@xxxxxxxxxxxxxxxx> wrote:
That is interesting. I would like to visit the museum some day. Here's
descriptions from a couple of the pictures.
"IBM's System/360 of the mid 1960s came in five different speed and size
ranges, starting at 4K of memory and eight 16-bit registers. The
architecture dominated business markets and computer science for three
decades."
Can you imagine that we once worked with computers with only 4K of
memory. Oh, and they successors of these are still very important in
the business world. Bill Gates just won't admit it.
"The PDP-8 from DEC was the first mass-produced minicomputer. By 1973 it
was the best-selling computer in the world, and over 25 years, DEC
produced more than a dozen variations of the PDP-8 architecture."
When I was in college I worked with a professor who was studying brain
waves. He had placed probes from a PDP-8 into the brains of mice (I
know - poor little mice), and I did the programming to produce analysis
reports.
Tom Kelman
Posted by Kopischke, David G.http://www.intelligententerprise.com/channels/information_management/sho
Sent: Tuesday, December 23, 2008 11:40 AM
Here's an interesting one from Intelligent Enterprise today....
- Computer History Museum Tour in Pictures
wArticle.jhtml?articleID=212501470&cid=nl_ie_weekHistory
By Doug Henschen
Our favorite event venue of 2008? Hands down it was the Computer
Museum in Mountain View, Calif. Take the tour in pictures.http://www.intelligententerprise.com/galleries/showImage.jhtml?galleryID
=23&imageID=1&articleID=212501470
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