Coolest in several ways. <a href="https://en.wikipedia.org/wiki/AN/AAR-47_Missile_Approach_Warning_System" rel="nofollow">https://en.wikipedia.org/wiki/AN/AAR-47_Missile_Approach_War...</a> I cannot talk about the tech. Which was cool. But I can talk about an event.<p>A military guy visited our place to give us a plaque of appreciation. He also had a picture. At the base, they asked people whose lives had been saved by our product, to come out for a quick picture. They had over 100 people show up. Being a part of a product that clearly saved all of those lives, plus many more, filled me with pride.<p>Hard to beat that for compensation, not all salaries are measured in cash.
Early in my career (as a co-op student) learning C on the job, I had to implement the HP PCL interpreter for a printer. The trick was it had so little memory (no page frame buffer) that you had to be very efficient and render into a short-height band across the page as the laser beam is rastering over the moving paper. Luckily I had hobby experience doing similar things on the Atari 8-bit. Some other student did the macros. A magazine did a benchmark test of a bunch of HP and compatible printers. Ours won most benchmarks except for storage efficiency for user-uploaded fonts which HP did better. They may have used more advanced compression. Partway through the project they took the hardware blitter out of spec to save like $12 so I had to replace it all in software including 0.25x,0.33x,0.5x,2x,3x,4x scaling which was also fun.
Not the coolest, but the one I enjoyed working on was a project to port Mortal Kombat: Dead Alliance game from GBA to a puny(but interesting) linux mobile phone. The linux phone had no graphics hardware acceleration where as GBA has. And I am no graphics expert, I am a generalist software engineer and there was no support or documentation* of the original source code and platform so it was super fun ;)<p>* Don't ask me why, there were some business reasons.
- Stealth aircraft<p>- Ground Moving Target Indicator: <a href="https://www.globalsecurity.org/military/systems/aircraft/systems/gmti.htm" rel="nofollow">https://www.globalsecurity.org/military/systems/aircraft/sys...</a><p>- Synthetic aperture radar (think ultra-high resolution radar that looks akin to HQ video)<p>- GPS (when it was originally in development by the military)