the "FIRST PC" - How about the computer on the Lunar Module?

From: Derek Peschel <dpeschel_at_u.washington.edu>
Date: Wed Apr 28 23:47:15 1999

> I was watching the show on the history of computers on the Discovery channel
> and they talked about the computer on the Lunar Module that landed on the
> moon. It had 5000 integrated circuits in it and was quite the marvel for
> its time. Could this be a candidate for the first Personal Computer? They
> were kinda pricey! ;-)

I'm not getting involved this time. Last time I tried, I just make myself
look silly.

> Does anybody have any information on that cpu - word size, instruction set,
> memory, control panel, etc? Who manuafactured it? Where can one go and see
> it (without going to the moon!) How about the software for it?

I don't know anything about the internals, except that they used braided-
wire memory to store the little "executive" (= a small OS with real-time
capabilities) which controlled the computer. I think the OS was written in
a language called HAL/S, although I may be getting the Apollo Guidance
Computer mixed up with the Space Shuttle computer. I have no idea if the
source or binary is available. The thing was designed to interface to radar
systems, electronics, power controllers, rocket engines, etc., so I think a
simulator would be pretty hard to write.

However, the manual is available! NASA published it as a report. I think
after the terrible fire that killed three astronauts, NASA had to rethink
the entire Apollo program, so they did a lot of soul-searching (along with
the accompanying paperwork). The user interface is rather spartan, because
the only displays are numerical. There are many specialized commands
("verbs" to NASA) and some operands ("nouns"). One command might
resynchronize the gyrocompasses, others do simple navigation, etc. I don't
believe there's a "Land On Moon" command. :)

I have the manual on my hard drive, and there might be a URL.

The first time I saw the AGC (one of them? how many were there?) it was on
display, but not working, at the Computer Museum in Boston. I don't
remember if they put plastic in front of the keypad... there wouldn't have
been much point in pressing the keys anyway.

The other time I saw the AGC, it was in a cardboard box in the Computer
Museum History Center warehouse in Moffett Field. They had just moved in --
I was poking around -- "What's in THIS box? Oh, it's the PDP-1 broken down
to individual System Modules! And this box is the AGC, and that box..."
Rather awe-inspiring actually.

> An simulator for one would be pretty cool to see, especially if it was
> running the program that they used to land on the moon!

As I said, you would need details about all the other hardware. Yes, it
would be cool, but I'm not very optimistic.

-- Derek
Received on Wed Apr 28 1999 - 23:47:15 BST