
Detailed articles on the avionics of NASA’s space shuttle - stevenhuang
https://spaceflight.nasa.gov/shuttle/reference/shutref/orbiter/avionics/
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exikyut
This is awesome.

But it has no pictures! And the font is so _tiny_ :( my eyes can read it, but
my brain's getting scared by the walls of text.

What I'd love to see is photos of the various modules, and then further photos
of all the insides.

\--

Probably the thing I want the most - as crazy as this probably sounds - is a
character ROM dump. I like fonts from old things :/

I recently learned that the bit of avionics with the weird keyboard in it
that's typically found in "large" aircraft is called a Control Display Unit,
or CDU. (Here's a random 747 cockpit with two shown facing upwards:
[http://flic.kr/p/aFRHt4](http://flic.kr/p/aFRHt4)). I did an image search for
CDU font, and promptly had one of those times I immediately hit the jackpot:
[http://sigmatechnica.com/lynx-helecopter-cdu-semi-
teardown/](http://sigmatechnica.com/lynx-helecopter-cdu-semi-teardown/) has a
2048x1536 photo of someone who randomly got a CDU from a Lynx helicopter off
eBay to poke at, and took a bunch of photos of everything they could make it
do, _including the font-self test!_

That's the kind of thing I wish I had, but for random industrial equipment -
and, sure, the space shuttle. (Know where I can find ROMs for old avionics?
lol)

For the VT220 font-rendering geeks, the CRT in the mentioned CDU (no model
info :( ) happens to be mounted vertically.

~~~
dexen
From the second link,

 _> Interestingly the indicators are incandescent bulbs…_

 _> an odd choice as they have used LEDs as indicators on the PCBs as we will
see later._

Lightbulbs have well-understood failure mode (open circuit) and detection of
such failures; it's exceedingly rare for a lightbulb to fail half-way.
Contrast that with LEDs which can fail while remaining as either open or
closed circuit. This (costly & lengthy airworthiness certification aside) is
why even modern airliners use lightbulbs for avionics indicators - often in
redundant pairs. One of very few maintenance items commercial pilots are
allowed, and indeed trained, to perform routinely is replacing the indicator
lighbulbs.

In-depth coverage by Mentour Pilot:
[https://www.youtube.com/watch?v=RifyTCwwNy0](https://www.youtube.com/watch?v=RifyTCwwNy0)

~~~
exikyut
TIL!

For a few seconds I started thinking about packaging LEDs with onboard LDRs so
any failure that results in not-100%-light-output produces an open circuit...
but I can see the result having too many moving parts to comfortably pass
certification. If such a thing is even possible to make.

Your mention that LEDs can fail closed rules out a current-consumption
monitoring system...

And then a "light up all the indicator lights" button (which IIRC does exist?)
connected to a camera and machine vision system would _work_, but it'd
probably be a ton more expensive (to build _properly_) than just sticking with
incandescent bulbs.

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qume
Wow this covers a lot of my job, and is really concise and well written.

This might be the best link ever posted to HN for me. Thank you.

~~~
exikyut
What kind of job do you do? My vague guess is NASA historian or tour guide.

~~~
petermcd
These articles would be of interest to anyone developing flight avionics
systems for spacecraft, airplanes, or, I can imagine, drones.

~~~
qume
Yea flight avionics, sort of. Aerial camera systems and the UI to control
them.

~~~
exikyut
Wow, that sounds really cool.

I really like the UI design that goes into avionics - the fact that every
possible scenario has to be thought out and handled, and that the end result
has no flashy eyecandy or extraneous functionality; it's all function, it's
all required (or it's not there); everything on the screen at any given time
is significant, and (hopefully) care is taken that the amount of data (ie,
significance) showing at any one moment is not information overload. A very
hard balance to get right, I'm sure.

The rigor and discipline imposed over the process of software architecture and
implementation in aviation (moreso than medical devices, it would seem) is
both inspiring and instructive, and I definitely look up to it.

I must admit I'm genuinely interested to learn more about how the role of UI
design plays into avionics construction - I've leaned toward UX for quite a
while (I think I started headscratching about the subject around 13-14,
although I didn't know that was what it was called at the time) and I think
it's probably something I'd do pretty well at when I'm finally looking for a
job. Web UX is... frustrating and demotivating, though. I don't want to kill
myself doing that.

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forapurpose
There's much more than avionics if you navigate up the path:

[https://spaceflight.nasa.gov/shuttle/reference/](https://spaceflight.nasa.gov/shuttle/reference/)

