Comment by da_chicken
14 hours ago
An asynchronous scheduler with task priority, interrupts, and real-time response. That goes on a spaceship with less than 70 Watts of power available for the computer. That weighed about 70 pounds. When there has never been that sort of a multi-tasking computer controlled avionics before.
At a time when the contemporary computer systems that used asynchronous, priority-scheduled multitasking operating systems were things like IBM OS/360 mainframes and DEC PDP-6/PDP-10 minicomputers.
It was like having an Apple II in mid 1960s with double the word size.
I used san RTOS written in assembly for the Atmel AVR. AvrX (by John Barello)
You can look at the code here.
https://github.com/kororos/AvrX
Compiles down under 2k.
The thing is while actually doing that isn't crazy hard, they did that with hardly any existing examples to go by. And without modern tools.
And with a ROM that had to be hand sewn. No flash updates, just "little old ladies" working in a former bra factory for a defense contractor (and huge tax payer expense if any mistakes needed to be debugged).