The Apollo missions had technology no more complicated than a pocket calculator. From link here, there's an information about Apollo Guidance Computer (AGC)The on-board Apollo Guidance Computer (AGC) was about 1 cubic foot with 2K of 16-bit RAM and 36K of hard-wired core-rope memory with copper wires threaded or not threaded through tiny magnetic cores. The 16-bit words were generally 14 bits of data (or two op-codes), 1 sign bit, and 1 parity bit. The cycle time was 11.7 micro-seconds. Programming was done in assembly language and in an interpretive language, in reverse Polish.So, I've stumbled upon some source code when I researched what was up there, and I've noticed great comments (eg. TEMPORARY, I HOPE HOPE HOPE)VRTSTART    TS  WCHVERT# Page 801        CAF TWO     # WCHPHASE = 2 ---> VERTICAL: P65,P66,P67        TS  WCHPHOLD        TS  WCHPHASE        TC  BANKCALL    # TEMPORARY, I HOPE HOPE HOPE        CADR    STOPRATE    # TEMPORARY, I HOPE HOPE HOPE        TC  DOWNFLAG    # PERMIT X-AXIS OVERRIDE        ADRES   XOVINFLG        TC  DOWNFLAG        ADRES   REDFLAG        TCF VERTGUIDThe actual programs in the spacecraft were stored in core rope memory, an ancient memory technology made by (literally) weaving a fabric/rope, where the bits were physical rings of ferrite material. Core memory is resistant to cosmic rays. The state of a core bit will not change when bombarded by radiation in Outer Space. Virtual Apollo Guidance Computer (AGC) software is also on GITHUB!Some part of documentation is here.Another sample of source code with great comments.033911,000064: 32,3017    06037        FLAGORGY        TC       INTPRET      #  DIONYSIAN FLAG WAVING    034090,000243: 32,3241    13247        BZF      P63SPOT4               #  BRANCH IF ANTENNA ALREADY IN POSITION 1    034091,000244:     034092,000245: 32,3242    33254        CAF      CODE500                #  ASTRONAUT:     PLEASE CRANK THE    034093,000246: 32,3243    04616        TC       BANKCALL               #                 SILLY THING AROUND    034094,000247: 32,3244    20623        CADR     GOPERF1                                   034095,000248: 32,3245    16001        TCF      GOTOP00H               #  TERMINATE    034096,000249: 32,3246    13235        TCF      P63SPOT3               #  PROCEED        SEE IF HE'S LYING    034101,000254: 32,3251    04635        TC       POSTJUMP               #  OFF TO SEE THE WIZARD ...    034102,000255: 32,3252    74126        CADR     BURNBABYMy question here is this:How were the teams writing this much code able to make it functional given the tools at the time?Because if you compile so much code that was used on Apollo 11... it'd take days, even weeks. I seriously doubt that programmers back then left everything to happen by chance. 
Development process used for the code on Apollo 11 missions?
history;assembly;low level;imperative programming;space technology
If I understand correctly, the development process was peer review and experimentation. The team consisted of people like Math Doctors - extremely dedicated, intelligent, passionate, detail-oriented folks whose lives were dedicated to their work. So when I say peer review, I mean many peer reviews over the course of many months (more than a year).These developers ran the simulations in their heads, debugged the software on paper and worked in groups with many developers looking at the same code over and over until they were convinced it was correct. There were multiple teams - each working on a part of the whole. My Numerical Methods professor at The Ohio State University (Spring '96) wrote the code that decided when to kick off a stage of the booster rocket. He described the printout being the size of the phone book (So, maybe 2.5 to 3.5 inches thick of 8.5 x 11 inch paper - he didn't describe the font size) of Fortran code. When convinced, they launched an unmanned missile (rockets technically don't have gyroscopes) with a radio on board that emitted a beep at regular intervals. They listened to the beeps up to the point they expected the radio to impact the moon (crash into it and destroy itself) and stop beeping. They knew that if they missed, the radio would keep beeping long past the calculated time of impact. Impact occurred 15 seconds after the calculated time. This admitedly anecdotal story are my recollections from an office visit with the doctor. He was very old, and it was a long time ago. This is my best recollection. 