Text 125, 115 rader
Skriven 2006-05-31 18:46:32 av Peter Knapper (3:772/1.10)
    Kommentar till text 124 av Bob Ackley (1:2905/3)
Ärende: eCS 1 of 4.
===================
Hi Bob,

 PK> For some memories, you may find this article interesting........;-)

 PK>   http://homepages.kcbbs.gen.nz/nbree/saga.html

 BA> Sorry.  No internet access.

Ok, Lets see if I can post it here then as its 99.9% text..
Part 1 of 4...

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  Lawrence Wilkinson's IBM 360/30 Saga

------------------------------------------------------------------------

Newsgroups: alt.folklore.computers
Subject: IBM 360/30 saga (long)
Date: Thu, 29 Jun 95 18:50:26 GMT
Lines: 417

For those looking forward to it, here it is. To the others, sorry for
clogging up a.f.c. Having just re-read it, I can't believe I ever
managed to do all this. LJW 29-Jun-95.

What follows is quite true, to the best of my recollections. I am a bit
sketchy on many of the specifics, as most of this happened over ten
years ago. I apologise in advance to anyone who helped out and has been
denied a mention. LJW 16-May-93.

This story starts some time mid 1982, when I was in my second year of an
electrical engineering degree and involved with the NZ Microcomputer
Club. At that time I still had an 8080-based S100 system, complete with
8k RAM and KC standard cassette, but had done quite a bit of work on
TRS80 clones, Sorcerers and the like.

Someone in the NZMC had been told of the existence of a computer in a
cartage company's warehouse, which they wanted to get rid of. With no
idea of what to expect, myself and several other club members (Selwyn
Arrow and Trevor Sheffield, I think) went along one evening to the
building in central Auckland to have a look. With virtually no light,
all we could see almost buried in between sacks of spices and goodness
knows what else were several large cabinets. After a bit of clambering
and moving of stuff, we ascertained that it was an IBM, and the cabinets
had the model numbers 2030 and 2841 on the side. There were also several
smaller units, which were pretty obviously disk drives.

Never having had anything to do with IBM products before, none of us
knew what it was, but I was sure of one thing: If they didn't want it, I
did! The club had hopes of starting a BBS, but the size of the unit was
a bit excessive, even if the price was right. Anyway, it was there for
the asking, all we needed was somewhere to put it, and the company would
move it for free. An agreement was drawn up between me and the club (the
OSI club, represented by Brian Wilson, was also involved.)

At the time I was doing some programming work (1802, 6800 etc.) for a
friend (Steven Murray) who had a small office (like about 3m square) in
downtown Auckland, and next to him there was a larger vacant room. The
rent was about $120 per month. I don't know how I afforded it back then,
but I took it. The catch was, it was on the third floor, and there was
only a winding staircase and a tiny lift for access, so it obviously
wasn't going to fit up there in one piece.

I opted to have the main units brought home, where they took up most of
one side of our carport, while the smaller pieces like the drives went
straight to the office. There were plenty of huge blue manuals, about 50
disk packs and various other odds and ends. At some stage the identity
of the machine was revealed when the nameplate turned up: "IBM
System/360". After much reading at the library I worked out that what we
had was a Model 30, hence the 2030 number, which was a bit of a
disappointment when I would have liked a 91 or something.

All my spare time was taken up with studying the machine and the
manuals. It was obvious that the two main units would have to be
disassembled to get them into the office. The frames would fit up the
stairs, but if we were going to lift them then all their contents would
have to go separately. Unfortunately the IBM engineers had not taken
such disassembly into account, so it was not just a matter of unplugging
everything and unbolting it from the frame.

A few words about the construction of the unit are in order. As I became
'au fait' with the manuals I was able to identify the basic units. The
whole CPU was about 1.5m high by 1m wide by 2m long. Looking from the
front panel, the main power supply was at the left about 3/4 the way
back. It consisted of a huge three- phase transformer/filter assembly
and a high-frequency switching power supply. Behind it was an air
compressor (yes - more about this later) and a relay panel.

At the front left, near ground level, were the two core memory units.
Each was 32k bytes, and 64k was this system's maximum capability. Above
the core was the microcode storage, known as CCROS (card-capacitor read
only storage), in which microcode was stored on punched cards,
sandwiched statically between circuit boards. Each card held twelve
words of 60 bits, running long- ways along the card, and the card was
pressed against the circuit board by an air bladder, kept filled by the
aforementioned compressor. There were about 4k words of microcode, or
about 340 cards.

Virtually the whole right hand side of the machine was occupied by the
logic, on a 'gate' which swung out to provide access to the connections
on the rear. There was provision for a second gate of similar size,
though I learnt that this was only used if the floating point option
(which also required an additional CCROS unit) or a second selector
channel were fitted.

By the time I had sorted everything out I was pretty familiar with what
was inside. While the IBM 360 is of course a 32 bit machine, the Model
30 was internally an 8 bit system, so it had to do any computations four
times. Its addressing capability was restricted to 16 bits, hence the
64k core limit.

Contd...

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 * Origin: Another Good Point About OS/2 (3:772/1.10)