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