Does no digital copy of this exist to the public?
Don Eyles Walks Us Through the Lunar Module Source Code
21–30 of 52 posts
Re: Don Eyles Walks Us Through the Lunar Module Source Code
#22Does no digital copy of this exist to the public?
There are digital copies if you search around the Internet (at least a couple have been linked in other comments).
For me the most interesting part is that there are hand-written notes in this version which are from the development process.
Re: Don Eyles Walks Us Through the Lunar Module Source Code
#23Earlier quoted context omitted.
> I once had the very interesting experience of developing an in-place update for a mid-1980s-vintage spacecraft instrument: the magnetometer on the Galileo spacecraft. Sigh . Reading this at the start of my workday is not doing wonders to my morale. Only tangentially related to the article, but since you are commenting here, I'd like to thank you for the "Lisping at JPL". I've read it several times, which caused me…
> Reading this at the start of my workday is not doing wonders to my morale I'm very sorry to hear that. Would it help if I told you how my life sucks now? ;-) > Surely such a project should have generated way more research papers than it did? Since it doesn't seem to be used anymore, where's the source code? I have no idea. I strongly suspect that the RAX code was not preserved, though I could be wrong. You might wa…
> I'm very sorry to hear that. Would it help if I told you how my life sucks now? ;-)
I'm sure it does ;)
However: back in those days, computing skills were in mad demand (much more so than today, impressions to the contrary notwithstanding) and almost everything that you could do with a computer turned out to be something interesting and new.
With all the 'base' problems solved and the enormous resources available today the creativity and joy have definitely dropped a level or two. That doesn't mean that it isn't possible to derive some satisfaction of the creation of something but it is definitely harder to come by than it was in the days past.
Creativity explodes when there are more constraints, we are now for all practical purposes almost unconstrained.
Re: Don Eyles Walks Us Through the Lunar Module Source Code
#24The I/O on the diagram blows your mind, I wish the projects I worked on had outputs like Decent Engine
My career choices really suck, should have joined NASA or SpaceX :-)
Re: Don Eyles Walks Us Through the Lunar Module Source Code
#25There's mention of interpreted sections in the code. Do you know if it was possible to manually enter interpreted code to have it ran by the system afterward - or even program some of software by hand (being dictated hex) in case something unexpected occurring during the mission warranted it?
Re: Don Eyles Walks Us Through the Lunar Module Source Code
#26There's mention of interpreted sections in the code. Do you know if it was possible to manually enter interpreted code to have it ran by the system afterward - or even program some of software by hand (being dictated hex) in case something unexpected occurring during the mission warranted it?
All of the code was in read-only memory (core rope), so it was impossible to modify it.
There was at least one case when the behaviour of the code was significantly changed in flight to work around a hardware failure (shorted button). This involved changing the writable memory, which kept all the state, to selectively disable some parts of the lunar landing program. For more details see:
http://www.ibiblio.org/apollo/#Final_exam_for_the_advanced_s...
Re: Don Eyles Walks Us Through the Lunar Module Source Code
#27Earlier quoted context omitted.
> space probes occasionally do get software updates Sure. In 2014. Not in 1969. I once had the very interesting experience of developing an in-place update for a mid-1980s-vintage spacecraft instrument: the magnetometer on the Galileo spacecraft. It used an 1802 processor with 2k bytes of memory and was programmed in Forth. The development system ran on an Apple II. The instrument developed a bad byte of RAM and so a…
> Sure. In 2014. Not in 1969. The LM computer on Apollo 14 had to be updated in flight in order to bypass a faulty abort switch.[1] The patch was applied by radioing the instructions to the crew and having them enter it manually. [1] https://www.hq.nasa.gov/alsj/a11/a11.1201-pa.html
Note that this was not a code patch: This was a sequence of changes to the program state that tricked it into ignoring the abort switch. The code itself was stored in read only core rope memory, so it was physically impossible to change it (the memory was written by appropriately winding wires around ferrite cores).
EDIT: More details (in the form of a puzzle): http://www.ibiblio.org/apollo/#Final_exam_for_the_advanced_s...
Re: Don Eyles Walks Us Through the Lunar Module Source Code
#28Earlier quoted context omitted.
>with no hope of doing an update To be fair, space probes occasionally do get software updates, eg http://blogs.esa.int/rosetta/2014/03/28/software-upgrade-at-... In the case of the Curiosity Rover, it didn't even "ship" with the software of what it was supposed to do on Mars until it had landed there http://www.space.com/17034-mars-rover-curiosity-software-upg... Edit: I'm not saying this was possible in 1969. I pos…
> space probes occasionally do get software updates Sure. In 2014. Not in 1969. I once had the very interesting experience of developing an in-place update for a mid-1980s-vintage spacecraft instrument: the magnetometer on the Galileo spacecraft. It used an 1802 processor with 2k bytes of memory and was programmed in Forth. The development system ran on an Apple II. The instrument developed a bad byte of RAM and so a…
I guess that makes you R.G.?
Re: Don Eyles Walks Us Through the Lunar Module Source Code
#29Earlier quoted context omitted.
> space probes occasionally do get software updates Sure. In 2014. Not in 1969. I once had the very interesting experience of developing an in-place update for a mid-1980s-vintage spacecraft instrument: the magnetometer on the Galileo spacecraft. It used an 1802 processor with 2k bytes of memory and was programmed in Forth. The development system ran on an Apple II. The instrument developed a bad byte of RAM and so a…
I guess that makes you R.G.?
Yes. (Note the "about" link on https://news.ycombinator.com/user?id=lisper)
Re: Don Eyles Walks Us Through the Lunar Module Source Code
#30Earlier quoted context omitted.
Thats line printer output. Dot Matrix was only invented in the late 60s and in any case was too slow, being character at a time.
And you don't know terrifying power until you've seen a line printer going at full speed.
.. or the unworldly noise that a broken chain makes as it flails itself to death.