Reading old HP-65 program cards

[Gene Dorr]

Yes that is interesting -- I've looked at all those images many times and never noticed that before. It doesn't surprise me though -- as part of the documented procedure for preparing the "calculator kit" for flight, they put tape over the battery contacts of each of the six spare batteries packs. If you look at the photo of the three technicians preparing the calculators for flight (see the web page I've created -- hp65.genedorr.com -- under "Information from HP"), you'll see the the fellow on the right (Mason Mines) is placing tape over the contacts on one of the spare battery packs. Obviously they didn't want to chance any floating debris shorting the contacts of the calculator, either.

From what I've been able to gather, only one set of program cards was flown, and the set pictured is very probably the one flown. They *did* use them in flight -- the "ATS Pointing Program" was the primary means of getting the values used to point the spacecraft's high-gain antenna at the ATS-6 relay satellite. And while the maneuvering solutions were described as "backup" to the Apollo Guidance Computer (AGC), that doesn't mean they would only run them if the AGC failed: what really happened is that they used the HP-65 to compute the solutions for the engine burns, and then compared the resultant values to those they got from the AGC. It was, in a way, a technology demonstration, and they wanted to evaluate whether the HP-65 programs would produce useful results.

There are a lot of links in the web page I created -- including a link to the Smithsonian page. If you're at all interested in this topic, I really recommend checking it out. It has virtually everything I've found, except for the rather large "Qualification Test Report" document -- I had to submit a FOIA request to get that, and it's a bit too large (31Mb -- 111 pages) to provide via my web hosting service (plus, the first page of the PDF file is the response letter from NASA, which contains personal information I'd rather remove before making it publicly available).