Build your own Apollo Guidance Computer

Evan Koblentz evan at
Tue Dec 19 11:17:56 CST 2006

I checked with Frank O'Brien, who I work with at our museum (InfoAge Science
Center) here in New Jersey.  Frank is a researcher for the Apollo Lunar
Surface Journal and is co-editor of the Apollo Flight Journal.  He replied:

"In 2004, there were two people who *independently* reverse engineered the
guidance computer source*, and then wrote working hardware emulators. This
work was then used by the gent who built actual hardware to run the code.
Now, there is a not-very-well-organized effort to create an Apollo Guidance
Computer (AGC) using Field-Programmable Grid Arrays (FPGA's). FPGA's allow
you to create logic designs using high level design software, and the "burn"
the logic into the chip. In a sense, this is the step after breadboarding,
and before a chip gets mass produced. 

All the best, 

*Some of the source was unreadable, so it was recreated by playing with
memory checksums until the values worked out. Talk about dedication!"

I hope that's helpful!

- Evan

-----Original Message-----
From: Chuck Guzis [mailto:cclist at] 
Sent: Tuesday, December 19, 2006 2:40 AM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Build your own Apollo Guidance Computer 

On 18 Dec 2006 at 23:47, Richard wrote:

> I've seen this before; has anyone on cctalk built one?

Looks like a labor of love.

But, given that the original uses RTL and core, what's the point of building
one in LSTTL?  Why not use an FPGA?  It'd be no more or less authentic.  Or
perhaps just write a simulator to run on your PeeCee?

What's remarkable about the original is the size (2 cu. ft.) and the
modularity and serviceability.


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