Source Code
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These source-code files are part of a reconstructed copy of Comanche 44, the
initial release (though not the final mission release) of the Apollo 10
Command Module (CM) Apollo Guidance Computer (AGC) software. Subsequent releases
were Comanche 45 and Comanche 45/2 (the flown release on Apollo 10). The reconstruction
is believed to be exactly accurate, but in the absence of an actual Apollo-era
listing of Comanche 44, some explanation of the reconstruction process is needed
to insure confidence in that accuracy.
The starting point was the source code of Comanche 51
(separately previously reconstructed from an Apollo-era listing of Comanche 55,
flown on Apollo 11). Comanche 51 source code was then modified
by undoing changes known to have been made between revisions 44 and 51. The now-reconstructed
Comanche 44 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 printout,
although the source code would likely have different page numbers in a contemporary
Comanche 44 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 51. Here's a guide to the Apollo documentation referenced
in those annotations:
In most cases, only the titles (rather than the full texts) of PCRs are known. In addition to the
explanatory annotations, there is also
a step-by-step commentary about the reconstruction process.
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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021999,000002: ## Copyright: Public domain.
022000,000003: ## Filename: P76.agc
022001,000004: ## Purpose: A section of Comanche revision 044.
022002,000005: ## It is part of the reconstructed source code for the
022003,000006: ## original release of the flight software for the Command
022004,000007: ## Module's (CM) Apollo Guidance Computer (AGC) for Apollo 10.
022005,000008: ## The code has been recreated from a copy of Comanche 055. It
022006,000009: ## has been adapted such that the resulting bugger words
022007,000010: ## exactly match those specified for Comanche 44 in NASA drawing
022008,000011: ## 2021153D, which gives relatively high confidence that the
022009,000012: ## reconstruction is correct.
022010,000013: ## Assembler: yaYUL
022011,000014: ## Contact: Ron Burkey <info@sandroid.org>.
022012,000015: ## Website: www.ibiblio.org/apollo/index.html
022013,000016: ## Mod history: 2020-12-03 MAS Created from Comanche 51.
022014,000017:
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Page 511
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022016,000019: # 1) PROGRAM NAME - TARGET DELTA V PROGRAM (P76).
022017,000020: # 2) FUNCTIONAL DESCRIPTION - UPON ENTRY BY ASTRONAUT ACTION, P76 FLASHES DSKY REQUESTS TO THE ASTRONAUT
022018,000021: # TO PROVIDE VIA DSKY (1) THE DELTA V TO BE APPLIED TO THE OTHER VEHICLE STATE VECTOR AND (2) THE
022019,000022: # TIME (TIG) AT WHICH THE OTHER VEHICLE VELOCITY WAS CHANGED BY EXECUTION OF A THRUSTING MANEUVER. THE
022020,000023: # OTHER VEHICLE STATE VECTOR IS INTEGRATED TO TIG AND UPDATED BY THE ADDITION OF DELTA V (DELTA V HAVING
022021,000024: # BEEN TRANSFORMED FROM LV TO REF COSYS). USING INTEGRVS, THE PROGRAM THEN INTEGRATES THE OTHER
022022,000025: # VEHICLE STATE VECTOR TO THE STATE VECTOR OF THIS VEHICLE, THUS INSURING THAT THE W-MATRIX AND BOTH VEHICLE
022023,000026: # STATES CORRESPOND TO THE SAME TIME.
022024,000027: # 3) ERASABLE INITIALIZATION REQUIRED - NONE.
022025,000028: # 4) CALLING SEQUENCES AND EXIT MODES - CALLED BY ASTRONAUT REQUEST THRU DSKY V 37 E 76E.
022026,000029: # EXITS BY TCF ENDOFJOB.
022027,000030: # 5) OUTPUT - OTHER VEHICLE STATE VECTOR INTEGRATED TO TIG AND INCREMENTED BY DELTA V IN REF COSYS.
022028,000031: # THE PUSHLIST CONTAINS THE MATRIX BY WHICH THE INPUT DELTA V MUST BE POST-MULTIPLIED TO CONVERT FROM LV
022029,000032: # TO REF COSYS.
022030,000033: # 6) DEBRIS - OTHER VEHICLE STATE VECTOR.
022031,000034: # 7) SUBROUTINES CALLED - BANKCALL, GOXDSPF, CSMPREC (OR LEMPREC), ATOPCSM (OR ATOPLEM), INTSTALL, INTWAKE, PHASCHNG
022032,000035: # INTPRET, INTEGRVS, AND MINIRECT.
022033,000036: # 8) FLAG USE - MOONFLAG, CMOONFLAG, INTYPFLG, RASFLAG, AND MARKCTR.
022034,000037:
022035,000038: 30,2000 BANK 30
022036,000039: 13,2000 SETLOC P76LOC
022037,000040: 13,2000 BANK
022038,000041:
022039,000042: 13,2071 COUNT* $$/P76
022040,000043:
022041,000044: 13,2071 E7,1412 EBANK= TIG
022042,000045:
022043,000046: 13,2071 05546 P76 TC UPFLAG
022044,000047: 13,2072 00031 ADRES TRACKFLG
022045,000048:
022046,000049: 13,2073 32220 CAF V06N84 # FLASH LAST DELTA V,
022047,000050: 13,2074 04662 TC BANKCALL # AND WAIT FOR KEYBOARD ACTION.
022048,000051: 13,2075 20720 CADR GOFLASH
022049,000052: 13,2076 12212 TCF ENDP76
022050,000053: 13,2077 02101 TC +2 # PROCEED
022051,000054: 13,2100 02073 TC -5 # STORE DATA AND REPEAT FLASHING
022052,000055: 13,2101 32221 CAF V06N84 +1 # FLASH VERB 06 NOUN 33, DISPLAY LAST TIG,
022053,000056: 13,2102 04662 TC BANKCALL # AND WAIT FOR KEYBOARD ACTION.
022054,000057: 13,2103 20720 CADR GOFLASH
022055,000058: 13,2104 12212 TCF ENDP76
022056,000059: 13,2105 02107 TC +2
022057,000060: 13,2106 02101 TC -5
022058,000061: 13,2107 06006 TC INTPRET # RETURN TO INTERPRETIVE CODE
022059,000062: 13,2110 77745 DLOAD # SET D(MPAC)=TIG IN CSEC B28
022060,000063: 13,2111 03413 TIG
022061,000064: 13,2112 34041 STCALL TDEC1 # SET TDEC1=TIG FOR ORBITAL INTEGRATION
022062,000065: 13,2113 27105 OTHPREC
022063,000066: 13,2114 53575 COMPMAT VLOAD UNIT
022064,000067: 13,2115 00001 RATT
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Page 512
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022066,000069: 13,2116 77676 VCOMP # U(-R)
022067,000070: 13,2117 00031 STORE 24D # U(-R) TO 24D
022068,000071: 13,2120 53435 VXV UNIT # U(-R) X V = U(V X R)
022069,000072: 13,2121 00007 VATT
022070,000073: 13,2122 00023 STORE 18D
022071,000074: 13,2123 53435 VXV UNIT # U(V X R) X U(-R) = U((R X V) X R)
022072,000075: 13,2124 00031 24D
022073,000076: 13,2125 24015 STOVL 12D
022074,000077: 13,2126 03540 DELVOV
022075,000078: 13,2127 76505 VXM VSL1 # V(MPAC)=DELTA V IN REFCOSYS
022076,000079: 13,2130 00015 12D
022077,000080: 13,2131 77655 VAD
022078,000081: 13,2132 00007 VATT
022079,000082: 13,2133 00007 STORE 6 # V(PD6)=VATT + DELTA V
022080,000083: 13,2134 77624 CALL # PREVENT WOULD-BE USER OF ORBITAL
022081,000084: 13,2135 27442 INTSTALL # INTEG FROM INTERFERING WITH UPDATING
022082,000085: 13,2136 77624 CALL
022083,000086: 13,2137 26222 P76SUB1
022084,000087: 13,2140 53775 VLOAD VSR*
022085,000088: 13,2141 00007 6
022086,000089: 13,2142 57176 0,2
022087,000090: 13,2143 25543 STOVL VCV
022088,000091: 13,2144 00001 RATT
022089,000092: 13,2145 77657 VSR*
022090,000093: 13,2146 57176 0,2
022091,000094: 13,2147 15535 STODL RCV
022092,000095: 13,2150 03413 TIG
022093,000096: 13,2151 01517 STORE TET
022094,000097: 13,2152 71214 CLEAR DLOAD
022095,000098: 13,2153 01673 INTYPFLG
022096,000099: 13,2154 01571 TETTHIS
022097,000100: 13,2155 34041 INTOTHIS STCALL TDEC1
022098,000101: 13,2156 27135 INTEGRVS
022099,000102: 13,2157 77624 CALL
022100,000103: 13,2160 27442 INTSTALL
022101,000104: 13,2161 77624 CALL
022102,000105: 13,2162 26222 P76SUB1 # SET/CLEAR MOONFLAG
022103,000106: 13,2163 77775 VLOAD
022104,000107: 13,2164 00017 RATT1
022105,000108: 13,2165 01503 STORE RRECT
022106,000109: 13,2166 15535 STODL RCV
022107,000110: 13,2167 00015 TAT
022108,000111: 13,2170 25517 STOVL TET
022109,000112: 13,2171 00025 VATT1
022110,000113: 13,2172 77624 CALL
022111,000114: 13,2173 23435 MINIRECT
022112,000115: 13,2174 77776 EXIT
022113,000116: 13,2175 05412 TC PHASCHNG
022114,000117: 13,2176 04024 OCT 04024
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Page 513
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022116,000119: 13,2177 05546 TC UPFLAG
022117,000120: 13,2200 00236 ADRES REINTFLG
022118,000121:
022119,000122: 13,2201 06006 TC INTPRET
022120,000123: 13,2202 77624 CALL
022121,000124: 13,2203 26760 ATOPOTH
022122,000125: 13,2204 77531 SSP EXIT
022123,000126: 13,2205 00053 QPRET
022124,000127: 13,2206 26211 OUT
022125,000128: 13,2207 04662 TC BANKCALL # PERMIT USE OF ORBITAL INTEGRATION
022126,000129: 13,2210 27477 CADR INTWAKE1
022127,000130: 13,2211 77776 OUT EXIT
022128,000131: 13,2212 35021 ENDP76 CAF ZERO
022129,000132: 13,2213 55126 TS MARKCTR # CLEAR RR TRACKING MARK COUNTER
022130,000133: 13,2214 55125 TS VHFCNT
022131,000134:
022132,000135: 13,2215 37716 CAF NEGONE
022133,000136: 13,2216 55734 TS MRKBUF2 # INVALIDATE MARK BUFFER
022134,000137:
022135,000138: 13,2217 14106 TCF GOTOPOOH
022136,000139:
022137,000140: 13,2220 01524 V06N84 NV 0684
022138,000141: 13,2221 01441 NV 0633
022139,000142: 13,2222 67214 P76SUB1 CLEAR SLOAD
022140,000143: 13,2223 00263 MOONFLAG
022141,000144: 13,2224 00050 X2
022142,000145: 13,2225 43030 BHIZ SET # X2=0...CLEAR MOONFLAG
022143,000146: 13,2226 26230 +2 # =2.....SET MOONFLAG
022144,000147: 13,2227 00063 MOONFLAG
022145,000148: 13,2230 77616 RVQ
022146,000149:
End of include-file P76.agc. Parent file is MAIN.agc