11 Nov
2008
11 Nov
'08
9:11 a.m.
It had both core and rope
http://en.wikipedia.org/wiki/Core_rope_memory
Rod
-----Original Message-----
From: cctech-bounces at classiccmp.org
[mailto:cctech-bounces at classiccmp.org] On Behalf Of Chuck Guzis
Sent: 11 November 2008 07:40
To: General Discussion: On-Topic and Off-Topic Posts
Subject: RE: Who wants to help read a Saturn V core stack?
On 10 Nov 2008 at 22:37, dwight elvey wrote:
Reading shouldn't be too difficult. Outputs could
be recorded by a
digital scope. The rise times of the address and inhibit lines are
mostly to be slow enough that it doesn't cause the sense amplifier to
trip on the coupling in the selected address line.
Other addresses are protected by the matching signal on the inhibit
line. Any reasonably slow ramp would work since one is using a scope
to record and not a sense amp.
Putting to bed the idea of the "core rope" program store, the 1964
document on the launch computer is pretty clear that this is ordinary
read-write core storing the program:
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19730063841_19730
63841.pdf
In particular, item 2-37 begins "Reading a ferrite-core memory destroys
the information in the memory." It then goes on to describe the restore
part of a read operation. No mention of "core rope" is made. The
document, all 200-some pages contains a great deal of detail on the
computer, including memory operation and organization.
Cheers,
Chuck
14 Nov
14 Nov
2:22 a.m.
That article is referring to the AGC, which is not the computer we are
discussing. The AGC has already been solved.
There are four independent flight computers involved in an Apollo
mission.
The first is the LVDC, the Launch Vehicle Digital Computer, which flew
the Saturn booster. This is the one we are interested in. It was made
by IBM.
The second and third are the Command Module Computer (CMC) and the
Lunar Guidance Computer (LGC). These were both Apollo Guidance
Computers (AGCs) made by MIT. These are what most people are thinking
of when they think "Apollo Space Computer".
The last was a backup computer aboard the LM called the Abort Guidance
System, or AGS. It was made by TRW.
The software for the AGS, CMC, and LGC have already been recovered and
emulators of those exist and work.
The software for the LVDC however seems to have been destroyed or lost.
It was in the hands of IBM when they were broken up and nobody seems to
know what became of it. That is why this particular core stack is
interesting, it may have a copy of the lost LVDC software.
On Nov 11, 2008, at 8:11 AM, Rod Smallwood wrote:
It had both core and rope
http://en.wikipedia.org/wiki/Core_rope_memory
Rod
-----Original Message-----
From: cctech-bounces at classiccmp.org
[mailto:cctech-bounces at classiccmp.org] On Behalf Of Chuck Guzis
Sent: 11 November 2008 07:40
To: General Discussion: On-Topic and Off-Topic Posts
Subject: RE: Who wants to help read a Saturn V core stack?
On 10 Nov 2008 at 22:37, dwight elvey wrote:
Reading shouldn't be too difficult. Outputs
could be recorded by a
digital scope. The rise times of the address and inhibit lines are
mostly to be slow enough that it doesn't cause the sense amplifier to
trip on the coupling in the selected address line.
Other addresses are protected by the matching signal on the inhibit
line. Any reasonably slow ramp would work since one is using a scope
to record and not a sense amp.
Putting to bed the idea of the "core rope" program store, the 1964
document on the launch computer is pretty clear that this is ordinary
read-write core storing the program:
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19730063841_19730
63841.pdf
In particular, item 2-37 begins "Reading a ferrite-core memory destroys
the information in the memory." It then goes on to describe the restore
part of a read operation. No mention of "core rope" is made. The
document, all 200-some pages contains a great deal of detail on the
computer, including memory operation and organization.
Cheers,
Chuck
2:55 a.m.
On 14 Nov 2008 at 1:22, Daniel Seagraves wrote:
The first is the LVDC, the Launch Vehicle Digital
Computer, which flew
the Saturn booster. This is the one we are interested in. It was made
by IBM.
What I said before. The IBM docs for the LVDC are here and I would
encourage anyone who wants to offer a suggestion to reading the core
stack to read the document:
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19730063841_19730
63841.pdf
Even if you're not interested in recovering the LVDC core, the
document makes an extremely interesting read about the technology of
the time. One aspect in particular was the ability of the multiply
and divide instructions to run concurrently with other instructions.
Another aspect is the triple-redundant-with-voting structre of the
processor.
Cheers,
Chuck
10:31 p.m.
Chuck Guzis wrote:
What I said before. The IBM docs for the LVDC are
here and I would
encourage anyone who wants to offer a suggestion to reading the core
stack to read the document:
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19730063841_19730
63841.pdf
Even if you're not interested in recovering the LVDC core, the
document makes an extremely interesting read about the technology of
the time. One aspect in particular was the ability of the multiply
and divide instructions to run concurrently with other instructions.
Another aspect is the triple-redundant-with-voting structre of the
processor.
Fun read, presents a good primer on basic core memory principles too.
I only wish it had gone into more detail about the physical implementation such
as the ICs used, as it would be interesting to compare with the AGC. The only
mention I found suggests some DTL-class series. That and the power supply
voltages suggest it might be the TI Minuteman (SN3xx) series.
Perhaps it's in Vol II (?)
15 Nov
15 Nov
4:40 a.m.
On 14 Nov 2008 at 19:31, Brent Hilpert wrote:
I only wish it had gone into more detail about the
physical implementation such
as the ICs used, as it would be interesting to compare with the AGC. The only
mention I found suggests some DTL-class series. That and the power supply
voltages suggest it might be the TI Minuteman (SN3xx) series.
Perhaps it's in Vol II (?)
Here's volume II (Maintenance):
http://hdl.handle.net/2060/19730063842
Lots and lots of logic diagrams and a few schematics of the memory
assembly (mostly diode matrices), but no detail on the modules
themselves. (Tony would love the servicing instructions: "Replace
module with IBM Part No. XXXX".)
I wonder if a search of the USPTO library might turn up something.
Cheers,
Chuck
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RodSmallwood＠mail.ediconsulting.co.uk