Source Code
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These source-code files are part of a reconstructed copy of Artemis 071, the
first release of the Apollo 15 through 17 Command Module (CM) Apollo Guidance
Computer (AGC) software.
The reconstruction began with source code of Artemis 072 previously transcribed
from a digitized copy of that program. The code was then updated by undoing
changes between the two versions. The reconstruction was verified by matching
memory-bank checksums to those listed in drawing 2021154-. Note that page
numbers in the reconstructed code match those on the Artemis 072 printout,
although the changed code would likely have changed page numbers for a real
Artemis 071 listing.
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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058305,000002: ## Copyright: Public domain.
058306,000003: ## Filename: POWERED_FLIGHT_SUBROUTINES.agc
058307,000004: ## Purpose: A section of Artemis revision 071.
058308,000005: ## It is part of the reconstructed source code for the first
058309,000006: ## release of the flight software for the Command Module's
058310,000007: ## (CM) Apollo Guidance Computer (AGC) for Apollo 15 through
058311,000008: ## 17. The code has been recreated from a copy of Artemis 072.
058312,000009: ## It has been adapted such that the resulting bugger words
058313,000010: ## exactly match those specified for Artemis 071 in NASA
058314,000011: ## drawing 2021154-, which gives relatively high confidence
058315,000012: ## that the reconstruction is correct.
058316,000013: ## Reference: 1364
058317,000014: ## Assembler: yaYUL
058318,000015: ## Contact: Ron Burkey <info@sandroid.org>.
058319,000016: ## Website: www.ibiblio.org/apollo/index.html
058320,000017: ## Mod history: 2019-08-14 MAS Created from Artemis 072.
058321,000018:
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Page 1364
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058323,000020:
058324,000021: 23,2000 SETLOC POWFLITE
058325,000022: 23,2000 BANK
058326,000023:
058327,000024: 23,3530 0142 EBANK= DEXDEX
058328,000025: 23,3530 COUNT* $$/POWFL
058329,000026:
058330,000027: # CDUTRIG, CDUTRIG1, CDUTRIG2, AND CD*TR*GS ALL COMPUTE THE SINES AND
058331,000028: # COSINES OF THREE 2'S COMPLEMENT ANGLES AND PLACE THE RESULT, DOUBLE
058332,000029: # PRECISION, IN THE SAME ORDER AS THE INPUTS, AT SINCDU AND COSCDU. AN
058333,000030: # ADDITIONAL OUTPUT IS THE 1'S COMPLEMENT ANGLES AT CDUSPOT. THESE
058334,000031: # ROUTINES GO OUT OF THEIR WAY TO LEAVE THE MPAC AREA AS THEY FIND IT,
058335,000032: # EXCEPT FOR THE GENERALLY UNIMPORTANT MPAC +2. THEY DIFFER ONLY IN
058336,000033: # WHERE THEY GET THE ANGLES, AND IN METHOD OF CALLING.
058337,000034:
058338,000035: # CDUTRIG (AND CDUTRIG1, WHICH CAN BE CALLED IN BASIC) COMPUTE THE
058339,000036: # SINES AND COSINES FROM THE CURRENT CONTENTS OF THE CDU REGISTERS.
058340,000037: # THE CONTENTS OF CDUTEMP, ETC., ARE NOT TOUCHED SO THAT THEY MAY
058341,000038: # CONTINUE TO FORM A CONSISTENT SET WITH THE LATEST PIPA READINGS.
058342,000039:
058343,000040: # CDUTRIG1 IS LIKE CDUTRIG EXCEPT THAT IT CAN BE CALLED IN BASIC.
058344,000041:
058345,000042: # CD*TR*GS FINDS CDU VALUES IN CDUSPOT RATHER THAN IN CDUTEMP. THIS
058346,000043: # ALLOWS USERS TO MAKE TRANSFORMATIONS USING ARBITRARY ANGLES, OR REAL
058347,000044: # ANGLES IN AN ORDER OTHER THAN X Y Z. A CALL TO THIS ROUTINE IS
058348,000045: # NECESSARY IN PREPARATION FOR A CALL TO AX*SR*T IN EITHER OF ITS TWO
058349,000046: # MODES (SMNB OR NBSM). SINCE AX*SR*T EXPECTS TO FIND THE SINES AND
058350,000047: # COSINES IN THE ORDER Y Z X THE ANGLES MUST HAVE BEEN PLACED IN CDUSPOT
058351,000048: # IN THIS ORDER. CD*TR*GS NEED NOT BE REPEATED WHEN AX*SR*T IS CALLED
058352,000049: # MORE THAN ONCE, PROVIDED THE ANGLES HAVE NOT CHANGED. NOTE THAT SINCE
058353,000050: # IT CLOBBERS BUF2 (IN THE SINE AND COSINE ROUTINES) CD*TR*GS CANNOT BE
058354,000051: # CALLED USING BANKCALL. SORRY.
058355,000052:
058356,000053: # CD*TR*G IS LIKE CD*TR*GS EXCEPT THAT IT CAN BE CALLED IN
058357,000054: # INTERPRETIVE.
058358,000055:
058359,000056: 23,3530 77776 CDUTRIG EXIT
058360,000057: 23,3531 03534 TC CDUTRIGS
058361,000058: 23,3532 06006 TC INTPRET
058362,000059: 23,3533 77616 RVQ
058363,000060:
058364,000061: 23,3534 30032 CDUTRIGS CA CDUX
058365,000062: 23,3535 55175 TS CDUSPOT +4
058366,000063: 23,3536 30033 CA CDUY
058367,000064: 23,3537 55171 TS CDUSPOT
058368,000065: 23,3540 30034 CA CDUZ
058369,000066: 23,3541 55173 TS CDUSPOT +2
058370,000067:
058371,000068: 23,3542 00006 CD*TR*GS EXTEND
058372,000069: 23,3543 22142 QXCH TEM2
058373,000070: 23,3544 34766 CAF FOUR
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Page 1365
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058375,000072: 23,3545 76211 TR*GL**P MASK SIX # MAKE IT EVEN AND SMALLER
058376,000073: 23,3546 54143 TS TEM3
058377,000074: 23,3547 50143 INDEX TEM3
058378,000075: 23,3550 31171 CA CDUSPOT
058379,000076: 23,3551 52155 DXCH MPAC # STORING 2'S COMP ANGLE, LOADING MPAC
058380,000077: 23,3552 52127 DXCH VBUF +4 # STORING MPAC FOR LATER RESTORATION
058381,000078: 23,3553 04733 TC USPRCADR
058382,000079: 23,3554 51754 CADR CDULOGIC
058383,000080: 23,3555 00006 EXTEND
058384,000081: 23,3556 30155 DCA MPAC
058385,000082: 23,3557 50143 INDEX TEM3
058386,000083: 23,3560 53172 DXCH CDUSPOT # STORING 1'S COMPLEMENT ANGLE
058387,000084: 23,3561 04733 TC USPRCADR
058388,000085: 23,3562 01514 CADR COSINE
058389,000086: 23,3563 52155 DXCH MPAC
058390,000087: 23,3564 50143 INDEX TEM3
058391,000088: 23,3565 53150 DXCH COSCDU # STORING COSINE
058392,000089: 23,3566 00006 EXTEND
058393,000090: 23,3567 50143 INDEX TEM3
058394,000091: 23,3570 31172 DCA CDUSPOT # LOADING 1'S COMPLEMENT ANGLE
058395,000092: 23,3571 04733 TC USPRCADR
058396,000093: 23,3572 01526 CADR SINE +1 # SINE +1 EXPECTS ARGUMENT IN A AND L
058397,000094: 23,3573 52127 DXCH VBUF +4 # BRINGING UP PRIOR MPAC TO BE RESTORED
058398,000095: 23,3574 52155 DXCH MPAC
058399,000096: 23,3575 50143 INDEX TEM3
058400,000097: 23,3576 53142 DXCH SINCDU
058401,000098: 23,3577 10143 CCS TEM3
058402,000099: 23,3600 13545 TCF TR*GL**P
058403,000100: 23,3601 00142 TC TEM2
058404,000101:
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Page 1366
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058406,000103:
058407,000104: # ****************************************************************************************************************
058408,000105:
058409,000106: # QUICTRIG, INTENDED FOR GUIDANCE CYCLE USE WHERE TIME IS CRITICAL, IS A MUCH FASTER VERSION OF CD*TR*GS.
058410,000107: # QUICTRIG COMPUTES AND STORES THE SINES AND COSINES OF THE 2'S COMPLEMENT ANGLES AT CDUSPOT, CDUSPOT +2,
058411,000108: # AND CDUSPOT +4. UNLIKE CD*TR*GS, QUICTRIG DOES NOT LEAVE THE 1'S COMPLEMENT VERSIONS OF THE ANGLES IN
058412,000109: # CDUSPOT. QUICTRIG'S EXECUTION TIME IS 4.1 MS; THIS IS 10 TIMES AS FAST AS CD*TR*GS. QUICTRIG MAY BE
058413,000110: # CALLED FROM INTERPRETIVE AS AN RTB OP-CODE, OR FROM BASIC VIA BANKCALL OR IBNKCALL.
058414,000111:
058415,000112: 23,3602 00004 QUICTRIG INHINT # INHINT SINCE DAP USES THE SAME TEMPS
058416,000113: 23,3603 00006 EXTEND
058417,000114: 23,3604 22061 QXCH ITEMP1
058418,000115: 23,3605 34766 CAF FOUR
058419,000116: 23,3606 76211 +4 MASK SIX
058420,000117: 23,3607 54062 TS ITEMP2
058421,000118: 23,3610 50062 INDEX ITEMP2
058422,000119: 23,3611 31171 CA CDUSPOT
058423,000120: 23,3612 05061 TC SPSIN
058424,000121: 23,3613 00006 EXTEND
058425,000122: 23,3614 74753 MP BIT14 # SCALE DOWN TO MATCH INTERPRETER OUTPUTS
058426,000123: 23,3615 50062 INDEX ITEMP2
058427,000124: 23,3616 53142 DXCH SINCDU
058428,000125: 23,3617 50062 INDEX ITEMP2
058429,000126: 23,3620 31171 CA CDUSPOT
058430,000127: 23,3621 05060 TC SPCOS
058431,000128: 23,3622 00006 EXTEND
058432,000129: 23,3623 74753 MP BIT14
058433,000130: 23,3624 50062 INDEX ITEMP2
058434,000131: 23,3625 53150 DXCH COSCDU
058435,000132: 23,3626 10062 CCS ITEMP2
058436,000133: 23,3627 13606 TCF QUICTRIG +4
058437,000134: 23,3630 30061 CA ITEMP1
058438,000135: 23,3631 00003 RELINT
058439,000136: 23,3632 00000 TC A
058440,000137:
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Page 1367
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058442,000139:
058443,000140: # ****************************************************************************************************************
058444,000141:
058445,000142: # THESE INTERFACE ROUTINES MAKE IT POSSIBLE TO CALL AX*SR*T, ETC., IN
058446,000143: # INTERPRETIVE. LATER, WHERE POSSIBLE, THEY WILL BE ELIMINATED.
058447,000144:
058448,000145: # THESE INTERFACE ROUTINES ARE PERMANENT. ALL RESTORE USER'S EBANK
058449,000146: # SETTING. ALL ARE STRICT INTERPRETIVE SUBROUTINES, CALLED USING "CALL",
058450,000147: # RETURNING VIA QPRET. ALL EXPECT AND RETURN THE VECTOR TO BE TRANSFOR-
058451,000148: # MED INTERPRETER-STYLE IN MPAC; COMPONENTS AT MPAC, MPAC +3, AND MPAC +5.
058452,000149:
058453,000150: # TRG*SMNB AND TRG*NBSM BOTH EXPECT TO SEE THE 2'S COMPLEMENT ANGLES
058454,000151: # AT CDUSPOT (ORDER Y Z X, AT CDUSPOT, CDUSPOT +2, AND CDUSPOT +4; ODD
058455,000152: # LOCATIONS NEED NOT BE ZEROED). TRG*NBSM DOES THE NB TO SM TRANSFOR-
058456,000153: # MATION; TRG*SMNB, VICE VERSA.
058457,000154:
058458,000155: # CDU*NBSM DOES ITS TRANSFORMATION USING THE PRESENT CONTENTS OF
058459,000156: # THE CDU COUNTERS. OTHERWISE IT IS LIKE TRG*NBSM.
058460,000157:
058461,000158: # CDU*SMNB IS THE COMPLEMENT OF CDU*NBSM.
058462,000159:
058463,000160: 23,3633 77776 *SMNB* EXIT
058464,000161: 23,3634 07466 C*MM*N1 TC MPACVBUF # AX*SR*T EXPECTS VECTOR IN VBUF
058465,000162: 23,3635 46214 CS THREE # SIGNAL FOR SM TO NB TRANSFORMATION
058466,000163: 23,3636 03651 C*MM*N2 TC AX*SR*T
058467,000164: 23,3637 06006 TC INTPRET
058468,000165: 23,3640 43575 VLOAD RVQ
058469,000166: 23,3641 00123 VBUF
058470,000167:
058471,000168: 23,3642 77776 TRG*NBSM EXIT
058472,000169: 23,3643 03542 TC CD*TR*GS
058473,000170: 23,3644 07466 C*MM*N3 TC MPACVBUF # FOR AX*SR*T
058474,000171: 23,3645 36214 CA THREE # SIGNAL FOR NB TO SM TRANSFORMATION
058475,000172: 23,3646 13636 TCF C*MM*N2
058476,000173:
058477,000174: # *NBSM* AND *SMNB* EXPECT TO SEE THE SINES AND COSINES (AT SINCDU
058478,000175: # AND COSCDU) RATHER THAN THE ANGLES THEMSELVES. OTHERWISE THEY ARE
058479,000176: # LIKE TRG*NBSM AND TRG*SMNB.
058480,000177:
058481,000178: # NOTE THAT JUST AS CD*TR*GS NEED BE CALLED ONLY ONCE FOR EACH SERIES
058482,000179: # OF TRANSFORMATIONS USING THE SAME ANGLES, SO TOO ONLY ONE OF TRG*NBSM
058483,000180: # AND TRG*SMNB NEED BE CALLED FOR EACH SERIES. FOR SUBSEQUENT TRANSFOR-
058484,000181: # MATIONS USE *NBSM* AND *SMNB*.
058485,000182:
058486,000183: 23,3647 77776 *NBSM* EXIT
058487,000184: 23,3650 13644 TCF C*MM*N3
058488,000185:
058489,000186: # AX*SR*T COMBINES THE OLD SMNB AND NBSM. FOR THE NB TO SM
058490,000187: # TRANSFORMATION, ENTER WITH +3 IN A. FOR SM TO NB, ENTER WITH -3.
058491,000188: # THE VECTOR TO BE TRANSFORMED ARRIVES, AND IS RETURNED, IN VBUF.
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Page 1368
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058493,000190: # AX*SR*T EXPECTS TO FIND THE SINES AND COSINES OF THE ANGLES OF ROTATION
058494,000191: # AT SINCDU AND COSCDU, IN THE ORDER Y Z X. A CALL TO CD*TR*GS, WITH
058495,000192: # THE 2'S COMPLEMENT ANGLES (ORDER Y Z X) AT CDUSPOT, WILL TAKE CARE OF
058496,000193: # THIS. HERE IS A SAMPLE CALLING SEQUENCE:-
058497,000194:
058498,000195: # TC CDUTRIGS
058499,000196: # CS THREE ("CA THREE" FOR NBSM)
058500,000197: # TC AX*SR*T
058501,000198:
058502,000199: # THE CALL TO CD*TR*GS NEED NOT BE REPEATED, WHEN AX*SR*T IS CALLED MORE
058503,000200: # THAN ONCE, UNLESS THE ANGLES HAVE CHANGED.
058504,000201:
058505,000202: # AX*SR*T IS GUARANTEED SAFE ONLY FOR VECTORS OF MAGNITUDE LESS THAN
058506,000203: # UNITY. A LOOK AT THE CASE IN WHICH A VECTOR OF GREATER MAGNITUDE
058507,000204: # HAPPENS TO LIE ALONG AN AXIS OF THE SYSTEM TO WHICH IT IS TO BE TRANS-
058508,000205: # FORMED CONVINCES ONE THAT THIS IS A RESTRICTION WHICH MUST BE ACCEPTED.
058509,000206:
058510,000207: 23,3651 54142 AX*SR*T TS DEXDEX # WHERE IT BECOMES THE INDEX OF INDEXES
058511,000208: 23,3652 00006 EXTEND
058512,000209: 23,3653 22145 QXCH RTNSAVER
058513,000210:
058514,000211: 23,3654 10142 R*TL**P CCS DEXDEX # +3 --> 0 -3 --> 2
058515,000212: 23,3655 40142 CS DEXDEX # THUS: +2 --> 1 -2 --> 1
058516,000213: 23,3656 66214 AD THREE # +1 --> 2 -1 --> 0
058517,000214: 23,3657 00006 EXTEND
058518,000215: 23,3660 50000 INDEX A
058519,000216: 23,3661 33740 DCA INDEXI
058520,000217: 23,3662 52144 DXCH DEXI
058521,000218:
058522,000219: 23,3663 34770 CA ONE
058523,000220: 23,3664 54130 TS BUF
058524,000221: 23,3665 00006 EXTEND
058525,000222: 23,3666 50143 INDEX DEX1
058526,000223: 23,3667 40123 DCS VBUF
058527,000224: 23,3670 13672 TCF LOOP1 # REALLY BE A SUBTRACT, AND VICE VERSA
058528,000225:
058529,000226: 23,3671 52131 LOOP2 DXCH BUF # LOADING VECTOR COMPONENT, STORING INDEX
058530,000227:
058531,000228: 23,3672 52155 LOOP1 DXCH MPAC
058532,000229: 23,3673 33736 CA SINESLOC
058533,000230: 23,3674 60143 AD DEX1
058534,000231: 23,3675 54116 TS ADDRWD
058535,000232:
058536,000233: 23,3676 07056 TC DMPSUB # MULTIPLY BY SIN(CDUANGLE)
058537,000234: 23,3677 10142 CCS DEXDEX
058538,000235: 23,3700 52155 DXCH MPAC # NBSM CASE
058539,000236: 23,3701 13704 TCF +3
058540,000237: 23,3702 00006 EXTEND # SMNB CASE
058541,000238: 23,3703 40155 DCS MPAC
058542,000239: 23,3704 52134 DXCH TERM1TMP
058543,000240:
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Page 1369
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058545,000242: 23,3705 36211 CA SIX # SINCDU AND COSCDU (EACH 6 WORDS) MUST
058546,000243: 23,3706 26116 ADS ADDRWD # BE CONSECUTIVE AND IN THAT ORDER
058547,000244:
058548,000245: 23,3707 00006 EXTEND
058549,000246: 23,3710 50130 INDEX BUF
058550,000247: 23,3711 50143 INDEX DEX1
058551,000248: 23,3712 30123 DCA VBUF
058552,000249: 23,3713 52155 DXCH MPAC
058553,000250: 23,3714 07056 TC DMPSUB # MULTIPLY BY COS(CDUANGLE)
058554,000251: 23,3715 52155 DXCH MPAC
058555,000252: 23,3716 20134 DAS TERM1TMP
058556,000253: 23,3717 52134 DXCH TERM1TMP
058557,000254: 23,3720 20001 DDOUBL
058558,000255: 23,3721 50130 INDEX BUF
058559,000256: 23,3722 50143 INDEX DEX1
058560,000257: 23,3723 52123 DXCH VBUF
058561,000258: 23,3724 52131 DXCH BUF # LOADING INDEX, STORING VECTOR COMPONENT
058562,000259:
058563,000260: 23,3725 10000 CCS A # 'CAUSE THAT'S WHERE THE INDEX NOW IS
058564,000261: 23,3726 13671 TCF LOOP2
058565,000262:
058566,000263: 23,3727 00006 EXTEND
058567,000264: 23,3730 26142 DIM DEXDEX # DECREMENT MAGNITUDE PRESERVING SIGN
058568,000265:
058569,000266: 23,3731 10142 TSTPOINT CCS DEXDEX # ONLY THE BRANCHING FUNCTION IS USED
058570,000267: 23,3732 13654 TCF R*TL**P
058571,000268: 23,3733 00145 TC RTNSAVER
058572,000269: 23,3734 13654 TCF R*TL**P
058573,000270: 23,3735 00145 TC RTNSAVER
058574,000271:
058575,000272: 23,3736 01141 SINESLOC ADRES SINCDU # FOR USE IN SETTING ADDRWD
058576,000273:
058577,000274: 23,3737 00004 INDEXI DEC 4 B-14 # ********** DON'T **********
058578,000275: 23,3740 00002 DEC 2 B-14 # ********** TOUCH **********
058579,000276: 23,3741 00000 DEC 0 B-14 # ********** THESE **********
058580,000277: 23,3742 00004 DEC 4 B-14 # ********** CONSTANTS **********
058581,000278:
058582,000279: # ****************************************************************************************************************
058583,000280:
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Page 1370
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058585,000282:
058586,000283: # THIS SUBROUTINE COMPUTES INCREMENTAL CHANGES IN CDU(GIMBAL) ANGLES FROM INCREMENTAL CHANGES ABOUT SM AXES. IT
058587,000284: # REQUIRES SM INCREMENTS AS A DP VECTOR SCALED AT ONE REVOLUTION(DTHETASM,+2,+4). SIN,COS(CDUY,Z,X) ARE IN
058588,000285: # SINCDU,+2,+4 AND COSCDU,+2,+4 RESPECTIVELY, SCALED TO ONE HALF. CDU INCREENTS ARE PLACED IN DCDU,+2,+4 SCALED TO
058589,000286: # ONE REVOLUTION.
058590,000287:
058591,000288: # * COS(IGA)SEC(MGA) 0 -SIN(IGA)SEC(MGA) *
058592,000289: # * *
058593,000290: # * -COS(IGA)TAN(MGA) 1 SIN(IGA)TAN(MGA) *
058594,000291: # * *
058595,000292: # * SIN(IGA) 0 COS(IGA) *
058596,000293:
058597,000294: 23,2000 SETLOC POWFLIT1
058598,000295: 23,2000 BANK
058599,000296: 23,3743 COUNT* $$/POWFL
058600,000297: 23,3743 41345 SMCDURES DLOAD DMP
058601,000298: 23,3744 03212 DTHETASM
058602,000299: 23,3745 01150 COSCDUY
058603,000300:
058604,000301: 23,3746 41325 PDDL DMP
058605,000302: 23,3747 03216 DTHETASM +4
058606,000303: 23,3750 01142 SINCDUY
058607,000304:
058608,000305: 23,3751 77621 BDSU
058609,000306: 23,3752 77671 DDV
058610,000307: 23,3753 01152 COSCDUZ
058611,000308: 23,3754 03204 STORE DCDU
058612,000309:
058613,000310: 23,3755 72405 DMP SL1 # SCALE
058614,000311: 23,3756 01144 SINCDUZ
058615,000312: 23,3757 77621 BDSU
058616,000313:
058617,000314: 23,3760 03214 DTHETASM +2
058618,000315: 23,3761 17206 STODL DCDU +2
058619,000316: 23,3762 03212 DTHETASM
058620,000317:
058621,000318: 23,3763 65205 DMP PDDL
058622,000319: 23,3764 01142 SINCDUY
058623,000320: 23,3765 03216 DTHETASM +4
058624,000321:
058625,000322: 23,3766 43205 DMP DAD
058626,000323: 23,3767 01150 COSCDUY
058627,000324: 23,3770 77752 SL1
058628,000325: 23,3771 03210 STORE DCDU +4
058629,000326: 23,3772 77616 RVQ
End of include-file POWERED_FLIGHT_SUBROUTINES.agc. Parent file is MAIN.agc