
IBM 7030 Stretch - slater
https://en.wikipedia.org/wiki/IBM_7030_Stretch
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Taniwha
Famously the first (only?) computer that was repaired with an oil change:

"Of course, Stretch came originally with an oil-cooled core memory system.

Jack Worlton of the Los Alamos Scientific Laboratory (LASL) recalls a problem
experienced during the acceptance test phase, when there was a transient
memory error in the cores. The engineers worked for days to remedy the error
but were unable to figure out what was going wrong. They finally hit upon the
problem. As Worlton explains it, there was a piece of solder loose in the oil
bath, and because the oil was constantly in circulation the solder would move
and attach itself onto a core and cause an error. Then it would move and lodge
onto a different core and cause an error there.

It was the only error I know of that was corrected in a machine by giving it
an oil change, Worlton quips."

from : [http://www.chilton-
computing.org.uk/acl/literature/reports/p...](http://www.chilton-
computing.org.uk/acl/literature/reports/p018.htm)

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notacoward
My wife's parents met while working on system software for Stretch. From the
stories they've told it sounds like it was quite a beast even by the standards
of its day. IIRC, the I/O processor was incapable of running independently, so
programmers had to add special instructions in the middle of their own code to
give it cycles. Ick.

~~~
jacquesm
That's a cooperative synchronous bus, something quite common at the time. It's
a bit like a 'yield' instruction in a cooperative multitasking environment.

~~~
notacoward
It's a bit more than that. There's usually quite a bit of flexibility in when
to yield, and the consequences might not be that bad. These instructions had
to be issued in a very timely way, lest the whole system would come crashing
down. Was it unique in that regard? Perhaps not, though "common" is a bit
misleading when the computing landscape at the time was so small and
fragmented. The difference is that other architectures might have shared one
or two misfeatures with Stretch out of unfortunate necessity, but the Stretch
designers seemed determined to collect the entire set and then expand on it.
I'd guess that, like some projects I've been on, it was a case of one powerful
or well connected group of people pushing as much complexity as possible onto
another. So it's probably related to the "project management failure" sub-
thread.

~~~
ncmncm
Requiring periodic yields in user code strikes me as indicating a dedication
to simplicity. It was no great burden to add a few instructions to a program,
and it apparently saved them from needing to implement a forced, transparent
context switch mechanism.

~~~
notacoward
I think you're misunderstanding what we're talking about. This wasn't in user
code; it was in the OS ("MCP") itself. It wasn't a few instructions that could
be placed at convenient points in the control flow; it was _every N
instructions_ when I/O was active. Among other difficulties, that meant
accounting for that had to be part of even minor code changes. The people
actually doing it certainly didn't think it was simple or "no great burden" as
you suggest. Simple would have been an I/O unit that could run independently
of the main CPU, as in practically every machine designed since - including
the 360 which was designed by the same person. Even he apparently recanted
that decision.

So yeah, it's "a bit" like yield, but only in the sense that a Cessna and an
F-22 are "a bit" alike. I've done low-level work on multiple RISC processors
that had all sorts of exposed-pipeline and delegated-to-software functionality
(e.g. TLB handling on MIPS) in the name of simplicity, and I've even enjoyed
it somewhat, but I'm still glad I never had to work on anything as "raw" as
Stretch.

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rusteh1

      Weight: 70,000 pounds (35 short tons; 32 t)
      Power: 100 kW[1] @ 110 V
    

Incredible!

~~~
agumonkey
Consider an esp32 is probably faster in low power mode

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crispyambulance
Speaking of bad-ass computers, the 7030 was surpassed in speed in 1964 by the
CDC-6600, designed by Seymour Cray.

It had incredibly cool-looking DUAL circular displays and a minimalist console
keyboard built into the table...

[https://en.wikipedia.org/wiki/CDC_6600#/media/File:CDC_6600....](https://en.wikipedia.org/wiki/CDC_6600#/media/File:CDC_6600.jc.jpg)

~~~
ncmncm
I programmed one of those in Wirth Pascal, as a freshman at Oregon State
University in 1979. Then they retired it, installing a Honeywell running
Multics. Then, they replaced that with a Vax 750. It was a step down in
awesomeness each time.

The most popular parts of the 6600, as souvenirs, were the smoked-glass
cabinet doors.

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russellbeattie
I was just reading "A History of Pi" which mentions this computer and its
successor:

"π was computed to 250,000 decimal places on an IBM 7030 at the Commissariat à
l’Energie Atomique in Paris in February 1966, and a year later, in February
1967, a CDC 6600 was programmed by J. Gilloud and J. Filliatre, at the same
institution, to yield 500,000 decimal places. The program was again based on
Störmer’s formula (2) and the Shanks-Wrench method for checking the digits;
the running time was 28 hours and 10 minutes (of which 1 hour and 35 minutes
were used for conversion), and an additional 16 hours and 35 minutes were
needed for the check. These quarter- and half-million digit values of π were
published in reports of the Commissariat à l’Energie Atomique in Paris."

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equalunique
The creation of this machine is referenced in a book that's often cited here -
_The Mythical Man-Month_ \- just finished reading it today. It's quite
insightful for a book that's draws upon experiences from software projects as
far back as the 1950s.

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oofoe
STRETCH also makes an appearance in one of the classic Alfred Bester (the
writer, not the telepath) short stories:
[https://en.wikipedia.org/wiki/Something_Up_There_Likes_Me](https://en.wikipedia.org/wiki/Something_Up_There_Likes_Me)

Well worth a read if you can find it -- the Wikipedia summary is rather
spoiler-y and doesn't capture the charm of the story. Mr. Bester worked in
broadcast television at the time he wrote it and there is some amusing
commentary about ad trends of the day.

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Nr7
"PC World magazine named Stretch one of the biggest project management
failures in IT history." It would be interesting to know more about this. The
Wikipedia article doesn't really go into any detail and neither does the
source article.

For example, there's a comment about having to lower the clock speeds but it
doesn't say why this decision had to be made.

~~~
TheOtherHobbes
The germanium transistors used in Stretch simply weren't fast enough to meet
the paper spec. The architecture couldn't do much to work around this.

Cray at CDC used the newer and faster silicon transistors in the 6600. So did
IBM's later System/360.

In fact Cray _funded the development_ of the fast silicon transistors at
Fairchild with a $500k contract.

[https://www.computerhistory.org/siliconengine/silicon-
transi...](https://www.computerhistory.org/siliconengine/silicon-transistor-
exceeds-germanium-speed/)

IBM made the classic corporate mistake - sales over-promised and then told
engineering to build something that couldn't be built. So Stretch became an
involuntary R&D project instead of a commercial product.

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ncmncm
Stretch and the 6600 both had popcount instructions that x86 finally got in
SSSE3, only ten years ago.

This is sometimes interpreted as indicating NSA interest in the machine.

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olliej
Oh neat, it was 64bit!

I wonder if anyone has made an emulator for it yet?

~~~
forinti
It seems wasteful to me since it only had 2MB of RAM. It does say that
instructions could be 32 or 64 bits long, but I would guess having 16 or 32
bit instructions would let you pack more instructions into memory.

~~~
jacquesm
That's not 'only' that's absolutely mind warping huge for the time when it was
made. The physical dimensions of that memory were such that you could see the
individual bits as tiny little ferrite cores.

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cptnapalm
The next chapter from where I am in IBM's Early Computers is on the Strech
project meaning that I could be wealth of information if I read faster.

