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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065170,000002: ## Copyright: Public domain.
065171,000003: ## Filename: SPS_BACK-UP_RCS_CONTROL.agc
065172,000004: ## Purpose: A section of LUM69 revision 2.
065173,000005: ## It is part of the reconstructed source code for the flown
065174,000006: ## version of the flight software for the Lunar Module's (LM)
065175,000007: ## Apollo Guidance Computer (AGC) for Apollo 10. The code has
065176,000008: ## been recreated from a copy of Luminary revsion 069, using
065177,000009: ## changes present in Luminary 099 which were described in
065178,000010: ## Luminary memos 75 and 78. The code has been adapted such
065179,000011: ## that the resulting bugger words exactly match those specified
065180,000012: ## for LUM69 revision 2 in NASA drawing 2021152B, which gives
065181,000013: ## relatively high confidence that the reconstruction is correct.
065182,000014: ## Reference: pp. 1500-1502
065183,000015: ## Assembler: yaYUL
065184,000016: ## Contact: Ron Burkey <info@sandroid.org>.
065185,000017: ## Website: www.ibiblio.org/apollo/index.html
065186,000018: ## Mod history: 2019-07-27 MAS Created from Luminary 69.
065187,000019:
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Page 1500
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065189,000021: # PROGRAM NAME: SPSRCS
065190,000022:
065191,000023: # AUTHOR: EDGAR M. OSHIKA (AC ELECTRONICS)
065192,000024:
065193,000025: # MODIFIED: TO RETURN TO ALL AXES VIA Q BY P. S. WEISSMAN, OCT 7, 1968
065194,000026:
065195,000027: # FUNCTIONAL DESCRIPTION:
065196,000028:
065197,000029: # THIS PROGRAM CONTROLS THE FIRING OF ALL RCS JETS IN THE DOCKED CONFIGURATION ACCORDING TO THE FOLLOWING PHASE
065198,000030: # PLANE LOGIC.
065199,000031:
065200,000032: # 1. OUTER RATE LIMIT (SPSRCS)
065201,000033:
065202,000034: # IF MAGNITUDE OF EDOT IS GREATER THAN 1.73 DEG/SEC SET JET FIRING TIME, TJ, TO REDUCE RATE AND THEN RETURN TO
065203,000035: # CALLING PROGRAM (REQUESTING 4 JETS FOR P-AXIS).
065204,000036: # OTHERWISE, CONTINUE.
065205,000037:
065206,000038: # 2. RATE DEAD BAND TEST ( JTONTEST)
065207,000039:
065208,000040: # IF JETS ARE FIRING NEGATIVE AND RATE IS GREATER THAN -0.101 DEG/SEC, LEAVE JETS ON AND RETURN,
065209,000041: # IF JETS ARE FIRING POSITIVE AND RATE IS LESS THAN +0.101 DEG/SEC, LEAVE JETS ON AND RETURN, OTHERWISE CONTINUE.
065210,000042:
065211,000043: # 3. COASTING TEST (SPSSTART)
065212,000044:
065213,000045: # IF STATE (E,EDOT) IS BELOW LINE E + 4 X EDOT > -1.4 DEG AND EDOT IS LESS THAN 1.30 DEG/SEC SET JET TIME POSI-
065214,000046: # TIVE AND RETURN,
065215,000047: # IF STATE IS ABOVE LINE E + 4 X EDOT > +1.4 DEG AND EDOT IS GREATER THAN -1.30 DEG/SEC, SET JET TIME NEGATIVE
065216,000048: # AND RETURN,
065217,000049: # OTHERWISE, SET JET TIME ZERO AND RETURN.
065218,000050:
065219,000051: # THE MINIMUM PULSE WIDTH OF THIS CONTROLLER IS DETERMINED BY THE REPETITION RATE AT WHICH THIS ROUTINE IS CALLED
065220,000052: # AND IS NOMINALLY 100 MS FOR ALL AXES IN DRIFTING FLIGHT. DURING POWERED FLIGHT THE MINIMUM IS 100 MS FOR THE
065221,000053: # P AXIS AND 200 MS FOR THE CONTROL OF THE U AND V AXES.
065222,000054:
065223,000055: # CALLING SEQUENCE:
065224,000056:
065225,000057: # TC SPSRCS FROM Q,R AXES RCS AUTOPILOT
065226,000058: # INHINT FROM P-AXIS RCS AUTOPILOT
065227,000059: # TC IBNKCALL
065228,000060: # CADR SPSRCS
065229,000061:
065230,000062:
065231,000063: # EXIT:
065232,000064:
065233,000065: # TC Q
065234,000066: # ALARM/ABORT MODE: NONE
065235,000067:
065236,000068: # SUBROUTINES CALLED: NONE
065237,000069:
065238,000070: # INPUT: E, EDOT
065239,000071:
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Page 1501
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065241,000073: # TJP, TJV, TJU TJ MUST NOT BE NEGATIVE ZERO
065242,000074:
065243,000075: # OUTPUT: TJP, TJV, TJU
065244,000076: # NUMBERT = 6, WHEN RATE LIMITING P AXIS.
065245,000077:
065246,000078:
065247,000079: 17,3700 BANK 17
065248,000080: 17,2000 SETLOC DAPS2
065249,000081: 17,2000 BANK
065250,000082:
065251,000083: 17,3700 COUNT* $$/DAPBU
065252,000084:
065253,000085: 17,3700 E6,1525 EBANK= TJU
065254,000086: 17,3700 31425 SPSRCS CA EDOT
065255,000087: 17,3701 00006 EXTEND
065256,000088: 17,3702 74766 MP RATELIM1 # OUTER RATE LIMIT = 1.73 DEG/SEC
065257,000089: 17,3703 00006 EXTEND
065258,000090: 17,3704 13717 BZF JTONTEST
065259,000091:
065260,000092: 17,3705 54001 TS L
065261,000093: 17,3706 36241 CA SIX
065262,000094: 17,3707 55741 TS NUMBERT
065263,000095: 17,3710 10001 CCS L
065264,000096: 17,3711 13753 TCF NEGTHRST
065265,000097: 17,3712 05677 TC CCSHOLE # **TEMP ** FILL WITH A CONSTANT
065266,000098: 17,3713 17,3664 RATELIM2 = .1AT4 # = OCT 00632, 1.125 DEG/SEC
065267,000099: 17,3713 34736 POSTHRST CA HALF
065268,000100:
065269,000101: 17,3714 51476 NDX AXISCTR
065270,000102: 17,3715 55525 TS TJU
065271,000103: 17,3716 00002 TC Q
065272,000104:
065273,000105: 17,3717 51476 JTONTEST NDX AXISCTR
065274,000106: 17,3720 11525 CCS TJU
065275,000107: 17,3721 13725 TCF +4
065276,000108: 17,3722 13737 TCF SPSSTART
065277,000109: 17,3723 31425 CA EDOT
065278,000110: 17,3724 13726 TCF +2
065279,000111:
065280,000112: 17,3725 41425 +4 CS EDOT
065281,000113: 17,3726 22000 LXCH A
065282,000114: 17,3727 40111 CS DAPBOOLS # IF DRIFTBIT = 1, USE ZERO TARGET RATE
065283,000115: 17,3730 74744 MASK DRIFTBIT # IF DRIFTBIT = 0, USE 0.10 RATE TARGET
065284,000116: 17,3731 10000 CCS A
065285,000117: 17,3732 34767 CA RATEDB1
065286,000118: 17,3733 60001 AD L
065287,000119: 17,3734 00006 EXTEND
065288,000120: 17,3735 63737 BZMF +2
065289,000121: 17,3736 13716 TCF POSTHRST +3
065290,000122:
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Page 1502
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065292,000124: 17,3737 31425 SPSSTART CA EDOT
065293,000125: 17,3740 61750 AD E
065294,000126: 17,3741 00006 EXTEND
065295,000127: 17,3742 71411 MP DKDB # PAD LOADED DEADBAND. FRESHSTART: 1.4 DEG
065296,000128: 17,3743 00006 EXTEND
065297,000129: 17,3744 13761 BZF TJZERO
065298,000130:
065299,000131: 17,3745 00006 EXTEND
065300,000132: 17,3746 63755 BZMF +7
065301,000133: 17,3747 31425 CA EDOT
065302,000134: 17,3750 63664 AD RATELIM2
065303,000135: 17,3751 00006 EXTEND
065304,000136: 17,3752 63761 BZMF TJZERO
065305,000137: 17,3753 44736 NEGTHRST CS HALF
065306,000138: 17,3754 13714 TCF POSTHRST +1
065307,000139: 17,3755 43664 +7 CS RATELIM2
065308,000140: 17,3756 61425 AD EDOT
065309,000141: 17,3757 00006 EXTEND
065310,000142: 17,3760 63713 BZMF POSTHRST
065311,000143: 17,3761 34755 TJZERO CA ZERO
065312,000144: 17,3762 13714 TCF POSTHRST +1
065313,000145:
065314,000146:
065315,000147: 17,3763 4766 RATELIM1 = CALLCODE # = 00032, CORRESPONDING TO 1.73 DEG/SEC
065316,000148: 17,3763 4767 RATEDB1 = TBUILDFX # = 00045, CORRESPONDS TO 0.101 DEG/SEC
End of include-file SPS_BACK-UP_RCS_CONTROL.agc. Parent file is MAIN.agc