I write code for a living. But we web developers have it easy. Server-side scripting languages like PHP may look alien at first, but they’re pretty easy to pick up and intuitive enough that you can really get going pretty fast, and once you’re familiar with the basic principles, it’s not hard to look at a block of code and figure out what it does.
But programming in the old days was a much finer and darker art. System resources were scarce, and everything had to be as efficient as possible — on the computer hardware, at least. A lot more of the “processing” had to happen inside the brains of the programmers before any of the code was even written. Looking at this kind of old code fries my brain.
The most notorious example of old-school assembler code I’ve encountered is the language used to program the Atari 2600. That’s something I’ve never been willing to touch, myself. And it’s for something trivial — video games. But here’s something that really freaks me out: the original source code from Apollo 11. This code is every bit as inscrutable — or more — and it was mission critical: the lives of three astronauts, over 200,000 miles from Earth depended on it working flawlessly.
Well, they made it back, so I guess it worked. But looking at the code, I have no idea how. Here’s an excerpt:
GUILDEN EXTEND # IS UN-AUTO-THROTTLE DISCRETE PRESENT? # STERN # RSB 2009: Not originally a comment. READ CHAN30 MASK BIT5 CCS A TCF STARTP67 # YES P67NOW? TC CHECKMM # NO: ARE WE IN P67 NOW? DEC 67 TCF STABL? # NO STARTP66 TC FASTCHNG # YES TC NEWMODEX DEC66 DEC 66 EXTEND DCA HDOTDISP # SET DESIRED ALTITUDE RATE = CURRENT DXCH VDGVERT # ALTITUDE RATE. STRTP66A TC INTPRET SLOAD PUSH PBIASZ SLOAD PUSH PBIASY SLOAD VDEF PBIASX VXSC SET BIASFACT RODFLAG STOVL VBIAS TEMX VCOMP STOVL OLDPIPAX ZEROVECS STODL DELVROD RODSCALE STODL RODSCAL1 PIPTIME STORE LASTTPIP EXIT CAF ZERO TS FCOLD TS FWEIGHT TS FWEIGHT +1 VRTSTART TS WCHVERT
Source: Daring Fireball (of course).
