Source Code

These source-code files are part of a reconstructed copy of Luminary 173, the second (unflown) release of the Apollo 14 Lunar Module (LM) Apollo Guidance Computer (AGC) software.

The reconstruction began with reconstructed source code for Luminary 178. Changes between revision 173 and 178 were backed out, as described by Luminary memo 167 (revision 1). The reconstruction was verified by matching memory-bank checksums to those listed in drawing 2021152N. Note that page numbers in the reconstructed code match those for the baseline log section mentioned in each file's changelog; the page numbers for a real Luminary 173 listing would be different.

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.

064601,000002:                                                                                                  ## Copyright:   Public domain.
064602,000003:                                                                                                  ## Filename:    SPS_BACK-UP_RCS_CONTROL.agc
064603,000004:                                                                                                  ## Purpose:     A section of Luminary revision 173.
064604,000005:                                                                                                  ##              It is part of the reconstructed source code for the second
064605,000006:                                                                                                  ##              (unflown) release of the flight software for the Lunar
064606,000007:                                                                                                  ##              Module's (LM) Apollo Guidance Computer (AGC) for Apollo 14.
064607,000008:                                                                                                  ##              The code has been recreated from a reconstructed copy of
064608,000009:                                                                                                  ##              Luminary 178, as well as Luminary memo 167 (revision 1).
064609,000010:                                                                                                  ##              It has been adapted such that the resulting bugger words
064610,000011:                                                                                                  ##              exactly match those specified for Luminary 173 in NASA
064611,000012:                                                                                                  ##              drawing 2021152N, which gives relatively high confidence
064612,000013:                                                                                                  ##              that the reconstruction is correct.
064613,000014:                                                                                                  ## Reference:   pp. 1495-1498
064614,000015:                                                                                                  ## Assembler:   yaYUL
064615,000016:                                                                                                  ## Contact:     Ron Burkey <info@sandroid.org>.
064616,000017:                                                                                                  ## Website:     www.ibiblio.org/apollo/index.html
064617,000018:                                                                                                  ## Mod history: 2019-09-18 MAS  Created from Luminary 178.
064618,000019: 

Page 1495

064620,000021:                                                                                                  #  PROGRAM NAME:  SPSRCS
064621,000022: 
064622,000023:                                                                                                  #  AUTHOR:  EDGAR M. OSHIKA (AC ELECTRONICS)
064623,000024: 
064624,000025:                                                                                                  #  MODIFIED:  TO RETURN TO ALL AXES VIA Q BY P.S.WEISSMAN, OCT 7, 1968
064625,000026: 
064626,000027:                                                                                                  #  MODIFIED TO IMPROVE BENDING STABILITY BY G.KALAN,FEB.14,1969
064627,000028:                                                                                                  #  FUNCTIONAL DESCRIPTION:
064628,000029: 
064629,000030:                                                                                                  #  THIS PROGRAM CONTROLS THE FIRING OF ALL RCS JETS IN THE DOCKED CONFIGURATION ACCORDING TO THE FOLLOWING PHASE
064630,000031:                                                                                                  #  PLANE LOGIC.
064631,000032: 
064632,000033:                                                                                                  #  1. JET SENSE TEST (SPSRCS)
064633,000034: 
064634,000035:                                                                                                  #  IF JETS ARE FIRING NEGATIVELY,SET OLDSENSE NEGATIVE AND CONTINUE
064635,000036:                                                                                                  #  IF JETS ARE FIRING POSITIVELY,SET OLDSENSE POSITIVE AND CONTINUE
064636,000037:                                                                                                  #  IF JETS ARE NOT FIRING,SET OLDSENSE TO ZERO AND GO TO OUTER RATE LIMIT  TEST
064637,000038: 
064638,000039:                                                                                                  #  2. RATE DEAD BAND TEST
064639,000040: 
064640,000041:                                                                                                  #  IF JETS ARE FIRING NEGATIVELY AND RATE IS GREATER THAN TARGET RATE,LEAVE
064641,000042:                                                                                                  #  JETS ON AND GO TO INHIBITION LOGIC. OTHERWISE,CONTINUE.
064642,000043:                                                                                                  #  IF JETS ARE FIRING POSITIVELY AND RATE IS   LESS  THAN TARGET RATE,LEAVE
064643,000044:                                                                                                  #  JETS ON AND GO TO INHIBITION LOGIC. OTHERWISE,CONTINUE.
064644,000045: 
064645,000046:                                                                                                  #  3. OUTER RATE LIMIT TEST (SPSSTART)
064646,000047: 
064647,000048:                                                                                                  #  IF MAGNITUDE OF EDOT IS GREATER THAN 1.73 DEG/SEC SET JET FIRING TIME
064648,000049:                                                                                                  #   TO REDUCE RATE AND GO TO INHIBITION LOGIC. OTHERWISE,CONTINUE.
064649,000050: 
064650,000051:                                                                                                  #  4. COAST ZONE TEST
064651,000052: 
064652,000053:                                                                                                  #  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-
064653,000054:                                                                                                  #  TIVE AND CONTINUE. OTHERWISE,SET JET FIRING TIME TO ZERO AND CONTINUE.
064654,000055:                                                                                                  #  IF STATE IS ABOVE LINE  E + 4X EDOT > +1.4 DEG AND EDOT IS GREATER THAN -1.30 DEG/SEC, SET JET TIME NEGATIVE
064655,000056:                                                                                                  #  AND CONTINUE. OTHERWISE,SET JET FIRING TIME TO ZERO AND CONTINUE.
064656,000057: 
064657,000058:                                                                                                  #  5. INHIBITION LOGIC
064658,000059: 
064659,000060:                                                                                                  #  IF OLDSENSE IS NON-ZERO:
064660,000061:                                                                                                  #        A) RETURN IF JET TIME HAS SAME SIGN AS OLDSENSE
064661,000062:                                                                                                  #        B) SET INHIBITION COUNTER*AND RETURN IF JET TIME IS ZERO
064662,000063:                                                                                                  #        C) SET INHIBITION COUNTER,*SET JET TIME TO ZERO AND RETURN IF SIGN
064663,000064:                                                                                                  #           OF JET TIME IS OPPOSITE TO THAT OF OLDSENSE
064664,000065: 
064665,000066:                                                                                                  #  IF OLDSENSE IS ZERO:
064666,000067:                                                                                                  #        A) RETURN IF INHIBITION COUNTER IS NOT POSITIVE
064667,000068:                                                                                                  #        B) SET JET TIME TO ZERO AND RETURN IF INHIBITION COUNTER IS POSITIVE
064668,000069:                                                                                                  #  *NOTE: INHIBITION COUNTERS CAN BE SET TO 4 OR 10 FOR THE P,AND UV AXES,
064669,000070:                                                                                                  #  RESPECTIVELY,IN SPSRCS. THEY ARE DECREMENTED BY ONE AT THE BEGINNING OF

Page 1496

064671,000072:                                                                                                  #  EACH DAP PASS.
064672,000073: 
064673,000074:                                                                                                  #  THE MINIMUM PULSE WIDTH OF THIS CONTROLLER IS DETERMINED BY THE REPETITION  RATE AT WHICH THIS ROUTINE IS CALLED
064674,000075:                                                                                                  #  AND IS NOMINALLY 100 MS FOR ALL AXES IN DRIFTING FLIGHT.   DURING POWERED FLIGHT THE MINIMUM IS 100 MS FOR THE
064675,000076:                                                                                                  #  P AXIS AND 200 MS FOR THE CONTROL OF THE U AND V AXES.
064676,000077: 
064677,000078:                                                                                                  #  CALLING SEQUENCE:
064678,000079: 
064679,000080:                                                                                                  #           INHINT
064680,000081:                                                                                                  #                      TC     IBNKCALL
064681,000082:                                                                                                  #                      CADR   SPSRCS
064682,000083: 
064683,000084: 
064684,000085:                                                                                                  #  EXIT:
064685,000086:                                                                                                  #           TC     Q
064686,000087:                                                                                                  #  ALARM/ABORT MODE:    NONE
064687,000088: 
064688,000089:                                                                                                  #  SUBROUTINES CALLED:    NONE
064689,000090: 
064690,000091:                                                                                                  #  INPUT:      E,EDOT
064691,000092:                                                                                                  #              TJP, TJV, TJU                   TJ MUST NOT BE NEGATIVE ZERO
064692,000093: 
064693,000094:                                                                                                  #  OUTPUT:     TJP, TJV, TJU
064694,000095: 
064695,000096: 
064696,000097: 21,3640                                           BANK     21                                    
064697,000098: 21,2000                                           SETLOC   DAPS4                                 
064698,000099: 21,2000                                           BANK                                           
064699,000100: 
064700,000101: 21,3640                                           COUNT*   $$/DAPBU                              
064701,000102: 
064702,000103: 21,3640  E6,1525                                  EBANK=   TJU                                   
064703,000104: 21,3640           00632        RATELIM2           OCT      00632                                 #  1.125 DEG/SEC
064704,000105: 21,3641           34736        POSTHRST           CA       HALF                                  
064705,000106: 
064706,000107: 21,3642           51505                           NDX      AXISCTR                               
064707,000108: 21,3643           55525                           TS       TJU                                   
064708,000109: 21,3644           11744                           CCS      OLDSENSE                              
064709,000110: 21,3645           13665                           TCF      POSCHECK                              #  JETS FIRING POSITIVELY
064710,000111: 21,3646           13670                           TCF      CTRCHECK                              #  JETS OFF. CHECK INHIBITION CTR
064711,000112: 21,3647           51505        NEGCHECK           INDEX    AXISCTR                               #  JETS FIRING NEGATIVELY
064712,000113: 21,3650           41525                           CS       TJU                                   
064713,000114: 21,3651           10000                           CCS      A                                     
064714,000115: 21,3652           00002                           TC       Q                                     #  RETURN
064715,000116: 21,3653           13655                           TCF      +2                                    
064716,000117: 21,3654           13655                           TCF      +1                                    #  JETS COMMANDED OFF.SET CTR AND RETURN
064717,000118: 21,3655           51505        SETCTR             INDEX    AXISCTR                               #  JET FIRING REVERSAL COMMANDED. SET CTR,
064718,000119: 21,3656           33677                           CA       UTIME                                 #  SET JET TIME TO ZERO,AND RETURN

Page 1497

064720,000121: 21,3657           51505                           INDEX    AXISCTR                               
064721,000122: 21,3660           55767                           TS       UJETCTR                               
064722,000123: 21,3661           34755        ZAPTJ              CA       ZERO                                  
064723,000124: 21,3662           51505                           INDEX    AXISCTR                               
064724,000125: 21,3663           55525                           TS       TJU                                   
064725,000126: 21,3664           00002                           TC       Q                                     
064726,000127: 21,3665           51505        POSCHECK           INDEX    AXISCTR                               
064727,000128: 21,3666           31525                           CA       TJU                                   
064728,000129: 21,3667           13651                           TCF      NEGCHECK   +2                         
064729,000130: 21,3670           51505        CTRCHECK           INDEX    AXISCTR                               #  CHECK JET INHIBITION COUNTER
064730,000131: 21,3671           11767                           CCS      UJETCTR                               
064731,000132: 21,3672           13674                           TCF      +2                                    
064732,000133: 21,3673           00002                           TC       Q                                     #  CTR IS NOT POSITIVE. RETURN
064733,000134: 21,3674           13661                           TCF      ZAPTJ                                 #  CTR IS POSITIVE.INHIBIT FIRINGS
064734,000135: 21,3675           00002                           TC       Q                                     #  CTR IS NOT POSITIVE.RETURN
064735,000136: 21,3676           00004                           OCT      00004                                 
064736,000137: 21,3677           00012        UTIME              OCT      00012                                 
064737,000138: 21,3700           00012                           OCT      00012                                 
064738,000139: 21,3701  E6,1744               OLDSENSE           EQUALS   DAPTREG1                              
064739,000140: 21,3701           44753        NEGFIRE            CS       ONE                                   #  JETS FIRING NEGATIVELY
064740,000141: 21,3702           55744                           TS       OLDSENSE                              
064741,000142: 21,3703           31427                           CA       EDOT                                  
064742,000143: 21,3704           13710                           TCF      +4                                    
064743,000144: 21,3705           34753        PLUSFIRE           CA       ONE                                   
064744,000145: 21,3706           55744                           TS       OLDSENSE                              
064745,000146: 21,3707           41427                           CS       EDOT                                  #  RATE DEAD BAND TEST
064746,000147: 21,3710           22000                           LXCH     A                                     
064747,000148: 21,3711           40111                           CS       DAPBOOLS                              #  IF DRIFTBIT = 1, USE ZERO TARGET RATE
064748,000149: 21,3712           74744                           MASK     DRIFTBIT                              #  IF DRIFTBIT = 0, USE 0.10 RATE TARGET
064749,000150: 21,3713           10000                           CCS      A                                     
064750,000151: 21,3714           34767                           CA       RATEDB1                               
064751,000152: 21,3715           60001                           AD       L                                     
064752,000153: 21,3716           00006                           EXTEND                                         
064753,000154: 21,3717           63727                           BZMF     SPSSTART                              
064754,000155: 21,3720           13644                           TCF      POSTHRST   +3                         
064755,000156: 
064756,000157: 21,3721           51505        SPSRCS             INDEX    AXISCTR                               #  JET SENSE TEST
064757,000158: 21,3722           11525                           CCS      TJU                                   
064758,000159: 21,3723           13705                           TCF      PLUSFIRE                              #  JETS FIRING POSITIVELY
064759,000160: 21,3724           13726                           TCF      +2                                    
064760,000161: 21,3725           13701                           TCF      NEGFIRE                               #  JETS FIRING NEGATIVELY
064761,000162: 21,3726           55744                           TS       OLDSENSE                              #  JETS OFF
064762,000163: 21,3727           31427        SPSSTART           CA       EDOT                                  #  OUTER RATE LIMIT TEST
064763,000164: 21,3730           00006                           EXTEND                                         
064764,000165: 21,3731           74766                           MP       RATELIM1                              
064765,000166: 21,3732           10000                           CCS      A                                     
064766,000167: 21,3733           13752                           TCF      NEGTHRST                              #  OUTER RATE LIMIT EXCEEDED
064767,000168: 21,3734           13736                           TCF      +2                                    
064768,000169: 21,3735           13641                           TCF      POSTHRST                              #  OUTER RATE LIMIT EXCEEDED
064769,000170: 21,3736           31427                           CA       EDOT                                  #  COAST ZONE TEST
064770,000171: 21,3737           61751                           AD       E                                     

Page 1498

064772,000173: 21,3740           00006                           EXTEND                                         
064773,000174: 21,3741           71411                           MP       DKDB                                  #  PAD LOADED DEADBAND. FRESHSTART: 1.4 DEG
064774,000175: 21,3742           00006                           EXTEND                                         
064775,000176: 21,3743           13760                           BZF      TJZERO                                
064776,000177: 
064777,000178: 21,3744           00006                           EXTEND                                         
064778,000179: 21,3745           63754                           BZMF     +7                                    
064779,000180: 21,3746           31427                           CA       EDOT                                  
064780,000181: 21,3747           63640                           AD       RATELIM2                              
064781,000182: 21,3750           00006                           EXTEND                                         
064782,000183: 21,3751           63760                           BZMF     TJZERO                                
064783,000184: 21,3752           44736        NEGTHRST           CS       HALF                                  
064784,000185: 21,3753           13642                           TCF      POSTHRST   +1                         
064785,000186: 21,3754           43640                 +7        CS       RATELIM2                              
064786,000187: 21,3755           61427                           AD       EDOT                                  
064787,000188: 21,3756           00006                           EXTEND                                         
064788,000189: 21,3757           63641                           BZMF     POSTHRST                              
064789,000190: 21,3760           34755        TJZERO             CA       ZERO                                  
064790,000191: 21,3761           13642                           TCF      POSTHRST   +1                         
064791,000192: 
064792,000193: 
064793,000194: 21,3762     4766               RATELIM1           =        CALLCODE                              #  = 00032, CORRESPONDING TO 1.73 DEG/SEC
064794,000195: 21,3762     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