Source Code
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These source-code files are part of a reconstructed copy of Luminary 69/2,
the flown, final release of the Apollo 10 Lunar Module (LM) Apollo Guidance Computer (AGC) software.
The reconstruction is based on the source code of Luminary 69 — i.e., the
initial, unflown version, "revision 0" — of which
a contemporary listing was available. The code was then updated by incorporating the
differences between Luminary 69 and Luminary 69/2, known from other contemporary
documentation. The only such difference is the implementation in
Luminary 69/2 of the "R-2 Lunar Potential Model", the source code for which was taken
from program Luminary 99/1 (Apollo 11 LM), of which a contemporary listing was also available.
Finally, the now-reconstructed Luminary 69/2 was then validated by assembling it to
executable form and verifying that its memory banks had the correct checksums,
known from still other contemporary documentation.
Note that page numbers in the reconstructed code match those in the original Luminary 69
program listing, or in the ORBITAL INTEGRATION log section, in Luminary 99/1. Page numbers
would certainly differ somewhat in a contemporary Luminary 69/2 listing.
Moreover, annotations that were not present in the contemporary source code have been added
to the reconstructed code to justify each change in Luminary 69/2 relative to
Luminary 69. Here's a guide to the Apollo documentation referenced in those annotations:
Comments from the original source code are prefixed with a single '#' symbol,
whereas comments added later are prefixed by "##" or "###". Report any errors
noted by creating an
issue report at the Virtual AGC
project's GitHub repository.
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028775,000002: ## Copyright: Public domain.
028776,000003: ## Filename: GENERAL_LAMBERT_AIMPOINT_GUIDANCE.agc
028777,000004: ## Purpose: A section of LUM69 revision 2.
028778,000005: ## It is part of the reconstructed source code for the flown
028779,000006: ## version of the flight software for the Lunar Module's (LM)
028780,000007: ## Apollo Guidance Computer (AGC) for Apollo 10. The code has
028781,000008: ## been recreated from a copy of Luminary revsion 069, using
028782,000009: ## changes present in Luminary 099 which were described in
028783,000010: ## Luminary memos 75 and 78. The code has been adapted such
028784,000011: ## that the resulting bugger words exactly match those specified
028785,000012: ## for LUM69 revision 2 in NASA drawing 2021152B, which gives
028786,000013: ## relatively high confidence that the reconstruction is correct.
028787,000014: ## Reference: pp. 661-663
028788,000015: ## Assembler: yaYUL
028789,000016: ## Contact: Ron Burkey <info@sandroid.org>.
028790,000017: ## Website: www.ibiblio.org/apollo/index.html
028791,000018: ## Mod history: 2019-07-27 MAS Created from Luminary 69.
028792,000019:
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Page 661
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028794,000021:
028795,000022: # GENERAL LAMBERT AIMPOINT GUIDANCE **
028796,000023: # WRITTEN BY RAMA M AIYAWAR
028797,000024:
028798,000025: # PROGRAM P-31 DESCRIPTION **
028799,000026:
028800,000027: # 1. TO ACCEPT TARGETING PARAMETERS OBTAINED FROM A SOURCE EXTERNAL
028801,000028: # TO THE LEM AND COMPUTE THERE FROM THE REQUIRED-VELOCITY AND
028802,000029: # OTHER INITIAL CONDITIONS REQUIRED BY LM FOR DESIRED MANEUVER.
028803,000030: # THE TARGETING PARAMETERS ARE TIG (TIME OF IGNITION), TARGET
028804,000031: # VECTOR (RTARG), AND THE TIME FROM TIG UNTIL THE TARGET IS
028805,000032: # REACHED(DELLT4), DESIRED TIME OF FLIGHT FROM RINIT TO RTARG..
028806,000033:
028807,000034: # ASSUMPTIONS **
028808,000035:
028809,000036: # 1. THE TARGET PARAMETERS MAY HAVE BEEN LOADED PRIOR TO THE
028810,000037: # EXECUTION OF THIS PROGRAM.
028811,000038: # 2. THIS PROGRAM IS APPLICABLE IN EITHER EARTH OR LUNAR ORBIT.
028812,000039: # 3. THIS PROGRAM IS DESIGNED FOR ONE-MAN OPERATION, AND SHOULD
028813,000040: # BE SELECTED BY THE ASTRONAUT BY DSKY ENTRY V37 E31.
028814,000041:
028815,000042: # SUBROUTINES USED **
028816,000043: #
028817,000044: # MANUPARM, TTG/N35, R02BOTH, MIDGIM, DISPMGA, FLAGDOWN, BANKCALL,
028818,000045: # GOTOPOOH, ENDOFJOB, PHASCHNG, GOFLASHR, GOFLASH.
028819,000046:
028820,000047: # MANUPARM CALCULATES APOGEE, PERIGEE ALTITUDES AND DELTAV DESIRED
028821,000048: # FOR THE MANEUVER.
028822,000049:
028823,000050: # TTG/N35 CLOCKTASK - UPDATES CLOCK.
028824,000051:
028825,000052: # MIDGIM CALCULATES MIDDLE GIMBAL ANGLE FOR DISPLAY.
028826,000053:
028827,000054: # R02BOTH IMU - STATUS CHECK ROUTINE.
028828,000055:
028829,000056: # DISPLAYS USED IN P-31LM **
028830,000057:
028831,000058: # V06N33 DISPLAY SOTRED TIG (IN HRS. MINS. SECS)
028832,000059: # V06N42 DISPLAY APOGEE, PERIGEE, DELTAV.
028833,000060: # V16N35 DISPLAY TIME FROM TIG.
028834,000061: # V06N45 TIME FROM IGNITION AND MIDDLE GIMBAL ANGLE.
028835,000062:
028836,000063: # ERASABLE INITIALIZATION REQUIRED **
028837,000064:
028838,000065: # TIG TIME OF IGNITION DP (B+28) CS.
028839,000066:
028840,000067: # DELLT4 DESIRED TIME OF FLIGHT DP (B+28) CS
028841,000068: # FROM RINIT TO RTARG.
028842,000069: # RTARG RADIUS VECTOR OF TARGET POSITION VECTOR
028843,000070: # RADIUS VECTOR SCALED TO (B+29)METERS IF EARTH ORBIT
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Page 662
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028845,000072: # RADIUS VECTOR SCALED TO (B+27)METERS IF MOON ORBIT
028846,000073:
028847,000074: # OUTPUT **
028848,000075:
028849,000076: # HAPO APOGEE ALTITUDE
028850,000077: # HPER PERIGEE ALTITUDE
028851,000078: # VGDISP MAG.OF DELTAV FOR DISPLAY ,SCALING B+7 M/CS EARTH
028852,000079: # MAG.OF DELTAV FOR DISPLAY, SCALING B+5 M/CS MOON
028853,000080: # MIDGIM MIDDLE GIMBAL ANGLE
028854,000081: # XDELVFLG RESETS XDELVFLG FOR LAMBERT VG COMPUTATIONS
028855,000082:
028856,000083: # ALARMS OR ABORTS NONE **
028857,000084:
028858,000085: # RESTARTS ARE VIA GROUP 4 **
028859,000086:
028860,000087: 35,2000 SETLOC GLM
028861,000088: 35,2000 BANK
028862,000089:
028863,000090: 35,2414 E7,1466 EBANK= SUBEXIT
028864,000091:
028865,000092: 35,2414 COUNT* $$/P31
028866,000093: 35,2414 02325 P31 TC P20FLGON
028867,000094: 35,2415 32025 CAF V06N33 # TIG
028868,000095: 35,2416 03651 TC VNPOOH
028869,000096: 35,2417 06036 TC INTPRET
028870,000097: 35,2420 71214 CLEAR DLOAD
028871,000098: 35,2421 00670 UPDATFLG
028872,000099: 35,2422 03440 TIG
028873,000100: 35,2423 34041 STCALL TDEC1 # INTEGRATE STATE VECTORS TO TIG
028874,000101: 35,2424 27057 LEMPREC
028875,000102: 35,2425 40375 VLOAD SETPD
028876,000103: 35,2426 00001 RATT
028877,000104: 35,2427 00001 0D
028878,000105: 35,2430 03640 STORE RTIG
028879,000106: 35,2431 26327 STOVL RINIT
028880,000107: 35,2432 00007 VATT
028881,000108: 35,2433 03646 STORE VTIG
028882,000109: 35,2434 16335 STODL VINIT
028883,000110: 35,2435 32364 P30ZERO
028884,000111: 35,2436 65206 PUSH PDDL # E4 AND NUMIT = 0
028885,000112: 35,2437 03450 DELLT4
028886,000113: 35,2440 66015 DAD SXA,1
028887,000114: 35,2441 03440 TIG
028888,000115: 35,2442 03375 RTX1
028889,000116: 35,2443 03627 STORE TPASS4
028890,000117: 35,2444 45134 SXA,2 CALL
028891,000118: 35,2445 03376 RTX2
028892,000119: 35,2446 22000 INITVEL
028893,000120: 35,2447 41575 VLOAD PUSH
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Page 663
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028895,000122: 35,2450 03366 DELVEET3
028896,000123: 35,2451 03654 STORE DELVSIN
028897,000124: 35,2452 43046 ABVAL CLEAR
028898,000125: 35,2453 01267 XDELVFLG
028899,000126: 35,2454 37662 STCALL VGDISP
028900,000127: 35,2455 20021 GET.LVC
028901,000128: 35,2456 63375 VLOAD PDVL
028902,000129: 35,2457 03640 RTIG
028903,000130: 35,2460 02343 VIPRIME
028904,000131: 35,2461 77624 CALL
028905,000132: 35,2462 46277 PERIAPO1
028906,000133: 35,2463 77624 CALL
028907,000134: 35,2464 46407 SHIFTR1
028908,000135: 35,2465 77624 CALL # LIMIT DISPLAY TO 9999.9 N. MI.
028909,000136: 35,2466 45636 MAXCHK
028910,000137: 35,2467 16325 STODL HPER
028911,000138: 35,2470 00005 4D
028912,000139: 35,2471 77624 CALL
028913,000140: 35,2472 46407 SHIFTR1
028914,000141: 35,2473 77624 CALL # LIMIT DISPLAY TO 9999.9 N. MI.
028915,000142: 35,2474 45636 MAXCHK
028916,000143: 35,2475 02323 STORE HAPO
028917,000144: 35,2476 77776 EXIT
028918,000145: 35,2477 33666 CAF V06N81 # DELVLVC
028919,000146: 35,2500 03651 TC VNPOOH
028920,000147: 35,2501 32026 CAF V06N42 # HAPO, HPER, VGDISP
028921,000148: 35,2502 03651 TC VNPOOH
028922,000149: 35,2503 06036 TC INTPRET
028923,000150: 35,2504 45014 REVN1645 SET CALL # TRKMKCNT, TTOGO, +MGA
028924,000151: 35,2505 01071 FINALFLG
028925,000152: 35,2506 73542 VN1645
028926,000153: 35,2507 77650 GOTO
028927,000154: 35,2510 72504 REVN1645
End of include-file GENERAL_LAMBERT_AIMPOINT_GUIDANCE.agc. Parent file is MAIN.agc