Source Code
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These source-code files are part of a reconstructed copy of Comanche 51, the
initial release (though not the final mission release) of the Apollo 11
Command Module (CM) Apollo Guidance Computer (AGC) software. The flown, final
release was Comanche 55. The reconstruction is believed to be exactly accurate,
but in the absence of an actual Apollo-era listing of Comanche 51, some
explanation of the reconstruction process is needed to insure confidence in
that accuracy.
The starting point was the source code of Comanche 55, whose original source code
is available. Comanche 55 source code was then modified by undoing changes known
to have been made between revisions 51 and 55. The most-significant steps involved
reverting changes related to the R-2 lunar potential model, the details of which
were known from the previous, separate, independent reconstruction of the Apollo 10
Lunar Module software Luminary 69/2. The now-reconstructed
Comanche 51 source code was verified by assembling it and checking that the assembled
code had the expected known-correct memory-bank checksums. Note that page numbers in
the reconstructed code match those on the Comanche 55 or Luminary 69 printouts, although
the source code would likely have different page numbers in a contemporary Comanche 51 listing.
Annotations that were not present in the contemporary source code have been added to
the reconstructed code to justify each change relative to Comanche 55. Here's a guide
to some of the Apollo documentation relevant to those annotations:
Among documentation not actually referenced in the annotations, there is
a short writeup about the reconstruction process in our software repository
that may be helpful in understanding it from a different perspective. There's also
a handy table
that lists what the number of memory-words should be for each routine in Comanche 51,
which could make a nice double-check; however, we've not performed that double-check ourselves.
Comments expected to have been present in 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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021763,000002: ## Copyright: Public domain.
021764,000003: ## Filename: P76.agc
021765,000004: ## Purpose: A section of Comanche revision 051.
021766,000005: ## It is part of the reconstructed source code for the
021767,000006: ## original release of the flight software for the Command
021768,000007: ## Module's (CM) Apollo Guidance Computer (AGC) for Apollo 11.
021769,000008: ## The code has been recreated from a copy of Comanche 055. It
021770,000009: ## has been adapted such that the resulting bugger words
021771,000010: ## exactly match those specified for Comanche 51 in NASA drawing
021772,000011: ## 2021153D, which gives relatively high confidence that the
021773,000012: ## reconstruction is correct.
021774,000013: ## Reference: pp. 511-513
021775,000014: ## Assembler: yaYUL
021776,000015: ## Contact: Ron Burkey <info@sandroid.org>.
021777,000016: ## Website: www.ibiblio.org/apollo/index.html
021778,000017: ## Mod history: 2019-07-30 MAS Created from Comanche 55.
021779,000018:
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Page 511
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021781,000020: # 1) PROGRAM NAME - TARGET DELTA V PROGRAM (P76).
021782,000021: # 2) FUNCTIONAL DESCRIPTION - UPON ENTRY BY ASTRONAUT ACTION, P76 FLASHES DSKY REQUESTS TO THE ASTRONAUT
021783,000022: # TO PROVIDE VIA DSKY (1) THE DELTA V TO BE APPLIED TO THE OTHER VEHICLE STATE VECTOR AND (2) THE
021784,000023: # TIME (TIG) AT WHICH THE OTHER VEHICLE VELOCITY WAS CHANGED BY EXECUTION OF A THRUSTING MANEUVER. THE
021785,000024: # OTHER VEHICLE STATE VECTOR IS INTEGRATED TO TIG AND UPDATED BY THE ADDITION OF DELTA V (DELTA V HAVING
021786,000025: # BEEN TRANSFORMED FROM LV TO REF COSYS). USING INTEGRVS, THE PROGRAM THEN INTEGRATES THE OTHER
021787,000026: # VEHICLE STATE VECTOR TO THE STATE VECTOR OF THIS VEHICLE, THUS INSURING THAT THE W-MATRIX AND BOTH VEHICLE
021788,000027: # STATES CORRESPOND TO THE SAME TIME.
021789,000028: # 3) ERASABLE INITIALIZATION REQUIRED - NONE.
021790,000029: # 4) CALLING SEQUENCES AND EXIT MODES - CALLED BY ASTRONAUT REQUEST THRU DSKY V 37 E 76E.
021791,000030: # EXITS BY TCF ENDOFJOB.
021792,000031: # 5) OUTPUT - OTHER VEHICLE STATE VECTOR INTEGRATED TO TIG AND INCREMENTED BY DELTA V IN REF COSYS.
021793,000032: # THE PUSHLIST CONTAINS THE MATRIX BY WHICH THE INPUT DELTA V MUST BE POST-MULTIPLIED TO CONVERT FROM LV
021794,000033: # TO REF COSYS.
021795,000034: # 6) DEBRIS - OTHER VEHICLE STATE VECTOR.
021796,000035: # 7) SUBROUTINES CALLED - BANKCALL, GOXDSPF, CSMPREC (OR LEMPREC), ATOPCSM (OR ATOPLEM), INTSTALL, INTWAKE, PHASCHNG
021797,000036: # INTPRET, INTEGRVS, AND MINIRECT.
021798,000037: # 8) FLAG USE - MOONFLAG, CMOONFLAG, INTYPFLG, RASFLAG, AND MARKCTR.
021799,000038:
021800,000039: 30,2000 BANK 30
021801,000040: 13,2000 SETLOC P76LOC
021802,000041: 13,2000 BANK
021803,000042:
021804,000043: 13,2071 COUNT* $$/P76
021805,000044:
021806,000045: 13,2071 E7,1412 EBANK= TIG
021807,000046:
021808,000047: 13,2071 05546 P76 TC UPFLAG
021809,000048: 13,2072 00031 ADRES TRACKFLG
021810,000049:
021811,000050: 13,2073 32220 CAF V06N84 # FLASH LAST DELTA V,
021812,000051: 13,2074 04662 TC BANKCALL # AND WAIT FOR KEYBOARD ACTION.
021813,000052: 13,2075 20720 CADR GOFLASH
021814,000053: 13,2076 12212 TCF ENDP76
021815,000054: 13,2077 02101 TC +2 # PROCEED
021816,000055: 13,2100 02073 TC -5 # STORE DATA AND REPEAT FLASHING
021817,000056: 13,2101 32221 CAF V06N84 +1 # FLASH VERB 06 NOUN 33, DISPLAY LAST TIG,
021818,000057: 13,2102 04662 TC BANKCALL # AND WAIT FOR KEYBOARD ACTION.
021819,000058: 13,2103 20720 CADR GOFLASH
021820,000059: 13,2104 12212 TCF ENDP76
021821,000060: 13,2105 02107 TC +2
021822,000061: 13,2106 02101 TC -5
021823,000062: 13,2107 06006 TC INTPRET # RETURN TO INTERPRETIVE CODE
021824,000063: 13,2110 77745 DLOAD # SET D(MPAC)=TIG IN CSEC B28
021825,000064: 13,2111 03413 TIG
021826,000065: 13,2112 34041 STCALL TDEC1 # SET TDEC1=TIG FOR ORBITAL INTEGRATION
021827,000066: 13,2113 27105 OTHPREC
021828,000067: 13,2114 53575 COMPMAT VLOAD UNIT
021829,000068: 13,2115 00001 RATT
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021831,000070: 13,2116 77676 VCOMP # U(-R)
021832,000071: 13,2117 00031 STORE 24D # U(-R) TO 24D
021833,000072: 13,2120 53435 VXV UNIT # U(-R) X V = U(V X R)
021834,000073: 13,2121 00007 VATT
021835,000074: 13,2122 00023 STORE 18D
021836,000075: 13,2123 53435 VXV UNIT # U(V X R) X U(-R) = U((R X V) X R)
021837,000076: 13,2124 00031 24D
021838,000077: 13,2125 24015 STOVL 12D
021839,000078: 13,2126 03540 DELVOV
021840,000079: 13,2127 76505 VXM VSL1 # V(MPAC)=DELTA V IN REFCOSYS
021841,000080: 13,2130 00015 12D
021842,000081: 13,2131 77655 VAD
021843,000082: 13,2132 00007 VATT
021844,000083: 13,2133 00007 STORE 6 # V(PD6)=VATT + DELTA V
021845,000084: 13,2134 77624 CALL # PREVENT WOULD-BE USER OF ORBITAL
021846,000085: 13,2135 27442 INTSTALL # INTEG FROM INTERFERING WITH UPDATING
021847,000086: 13,2136 77624 CALL
021848,000087: 13,2137 26222 P76SUB1
021849,000088: 13,2140 53775 VLOAD VSR*
021850,000089: 13,2141 00007 6
021851,000090: 13,2142 57176 0,2
021852,000091: 13,2143 25543 STOVL VCV
021853,000092: 13,2144 00001 RATT
021854,000093: 13,2145 77657 VSR*
021855,000094: 13,2146 57176 0,2
021856,000095: 13,2147 15535 STODL RCV
021857,000096: 13,2150 03413 TIG
021858,000097: 13,2151 01517 STORE TET
021859,000098: 13,2152 71214 CLEAR DLOAD
021860,000099: 13,2153 01673 INTYPFLG
021861,000100: 13,2154 01571 TETTHIS
021862,000101: 13,2155 34041 INTOTHIS STCALL TDEC1
021863,000102: 13,2156 27135 INTEGRVS
021864,000103: 13,2157 77624 CALL
021865,000104: 13,2160 27442 INTSTALL
021866,000105: 13,2161 77624 CALL
021867,000106: 13,2162 26222 P76SUB1 # SET/CLEAR MOONFLAG
021868,000107: 13,2163 77775 VLOAD
021869,000108: 13,2164 00017 RATT1
021870,000109: 13,2165 01503 STORE RRECT
021871,000110: 13,2166 15535 STODL RCV
021872,000111: 13,2167 00015 TAT
021873,000112: 13,2170 25517 STOVL TET
021874,000113: 13,2171 00025 VATT1
021875,000114: 13,2172 77624 CALL
021876,000115: 13,2173 23435 MINIRECT
021877,000116: 13,2174 77776 EXIT
021878,000117: 13,2175 05412 TC PHASCHNG
021879,000118: 13,2176 04024 OCT 04024
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021881,000120: 13,2177 05546 TC UPFLAG
021882,000121: 13,2200 00236 ADRES REINTFLG
021883,000122:
021884,000123: 13,2201 06006 TC INTPRET
021885,000124: 13,2202 77624 CALL
021886,000125: 13,2203 26760 ATOPOTH
021887,000126: 13,2204 77531 SSP EXIT
021888,000127: 13,2205 00053 QPRET
021889,000128: 13,2206 26211 OUT
021890,000129: 13,2207 04662 TC BANKCALL # PERMIT USE OF ORBITAL INTEGRATION
021891,000130: 13,2210 27477 CADR INTWAKE1
021892,000131: 13,2211 77776 OUT EXIT
021893,000132: 13,2212 35021 ENDP76 CAF ZERO
021894,000133: 13,2213 55126 TS MARKCTR # CLEAR RR TRACKING MARK COUNTER
021895,000134: 13,2214 55125 TS VHFCNT
021896,000135:
021897,000136: 13,2215 37716 CAF NEGONE
021898,000137: 13,2216 55734 TS MRKBUF2 # INVALIDATE MARK BUFFER
021899,000138:
021900,000139: 13,2217 14106 TCF GOTOPOOH
021901,000140:
021902,000141: 13,2220 01524 V06N84 NV 0684
021903,000142: 13,2221 01441 NV 0633
021904,000143: 13,2222 67214 P76SUB1 CLEAR SLOAD
021905,000144: 13,2223 00263 MOONFLAG
021906,000145: 13,2224 00050 X2
021907,000146: 13,2225 43030 BHIZ SET # X2=0...CLEAR MOONFLAG
021908,000147: 13,2226 26230 +2 # =2.....SET MOONFLAG
021909,000148: 13,2227 00063 MOONFLAG
021910,000149: 13,2230 77616 RVQ
021911,000150:
End of include-file P76.agc. Parent file is MAIN.agc