Assembly listing generated by yaYUL

Source Code

These source-code files are part of a reconstructed copy of Skylark 048, the Block II Command Module (CM) Apollo Guidance Computer (AGC) software for the Skylab-2, Skylab-3, Skylab-4, and Apollo-Soyuz Test Project missions.

They have been created via disassembly of binary dumps of the original core rope memory modules actually flown on Skylab-2, part numbers 2010802-541, 2010802-551, 2010802-561, 2010802-571, 2010802-581, and 2010802-591. Access to these modules was provided by the New Mexico Museum of Space History, who we are much indebted to.

The source code for the Apollo 15, 16, and 17 software, Artemis 072, was used as a starting point. Heavy use was made of TRW 4900.5-244, Programmed Guidance Equations for Skylark Command Module Earth Orbital Program, dated 14 February 1972. This document contains pseudocode of essentially all of Skylark, using original program labels which have been copied for this source reconstruction.

Since only binary dumps (rather than listings) of Skylark are available as source material, all comments and labels are approximate. They have been taken from the Programmed Guidance Equations or other AGC programs where possible, or, in some places, written from scratch to match what we believe would have been in the original listing.

056627,000002: 056628,000003: 056629,000004: 056630,000005: 056631,000006: 056632,000007: 056633,000008: 056634,000009: 056635,000010: 056636,000011: 056637,000012: 056638,000013: 056639,000014: 056640,000015: 056641,000016: 01,2000 056642,000017: 01,2000 056643,000018: 056644,000019: 01,3475 E3,1436 056645,000020: 056646,000021: 01,3475 ## Copyright: Public domain. ## Filename: RESTARTS_ROUTINE.agc ## Purpose: A section of Skylark revision 048. ## It is part of the source code for the Apollo Guidance Computer (AGC) ## for Skylab-2, Skylab-3, Skylab-4, and ASTP. No original listings of ## this software are available; instead, this file was created via ## disassembly of dumps of the core rope modules actually flown on ## Skylab-2. Access to these modules was provided by the New Mexico ## Museum of Space History. ## Assembler: yaYUL ## Contact: Ron Burkey <info@sandroid.org>. ## Website: www.ibiblio.org/apollo/index.html ## Mod history: 2023-09-04 MAS Created from Artemis 072. SETLOC RESTART BANK EBANK= PHSNAME1 # GOPROG MUST SWITCH TO THIS EBANK COUNT* $$/RSROU 453">056647,000022: 01,3475 30161 RESTARTS CA MPAC +5 # GET GROUP NUMBER -1 60000 DOUBLE # SAVE FOR INDEXING 54155 TS TEMP2G 33135 CA PHS2CADR # SET UP EXIT IN CASE IT IS AN EVEN 54157 TS TEMPSWCH # TABLE PHASE 33534 CA RTRNCADR # TO SAVE TIME ASSUME IT WILL GET NEXT 54707 TS GOLOC +2 # GROUP AFTER THIS 30154 CA TEMPPHS 75037 MASK OCT1400 10000 CCS A # IS IT A VARIABLE OR TABLE RESTART 13520 TCF ITSAVAR # IT:S A VARIABLE RESTART 432">056662,000037: 01,3510 10154 GETPART2 CCS TEMPPHS # IS IT AN X.1 RESTART 10000 CCS A 13620 TCF ITSATBL # NO, ITS A TABLE RESTART 35065 CA PRIO14 # IT IS AN X.1 RESTART, THEREFORE START 452">056667,000042: 01,3514 05150 FVACCADR TC FINDVAC # THE DISPLAY RESTART ROUTINE (=GENADR) EBANK= LST1 03143 20063 2CADR INITDSP 03534 TC RTRNCADR # FINISHED WITH THIS GROUP, GET NEXT ONE 2">056674,000049: 01,3520 75037 ITSAVAR MASK OCT1400 # IS IT TYPE B ? 10000 CCS A 13571 TCF ITSLIKEB # YES, IT IS TYPE B 00006 EXTEND # STORE THE JOB (OR TASK) 2CADR FOR EXIT 50155 NDX TEMP2G 31437 DCA PHSNAME1 52706 DXCH GOLOC 30154 CA TEMPPHS # SEE IF THIS IS A JOB, TASK, OR A LONGCAL 75005 MASK OCT7 67701 AD MINUS2 10000 CCS A 13703 TCF ITSLNGCL # ITS A LONGCALL 452">056689,000064: 01,3534 04662 RTRNCADR TC SWRETURN # CANT GET HERE 13537 TCF ITSAWAIT 13604 TCF ITSAJOB # ITS A JOB 954">056693,000068: 01,3537 33471 ITSAWAIT CA WTLTCADR # SET UP WAITLIST CALL 54704 TS GOLOC -1 50155 NDX TEMP2G # DIRECTLY STORED 31250 CA PHSPRDT1 354">056698,000073: 01,3543 10000 TIMETEST CCS A # IS IT AN IMMEDIATE RESTART 24000 INCR A # NO, 13550 TCF FINDTIME # FIND OUT WHEN IT SHOULD BEGIN 15503 TCF ITSINDIR # STORED INDIRECTLY 13567 TCF IMEDIATE # IT WANTS AN IMMEDIATE RESTART # ***** THIS MUST BE IN FIXED FIXED ***** SETLOC FFTAG2 BANK COUNT* $$/RSROU 952">056712,000087: 5503 22706 ITSINDIR LXCH GOLOC +1 # GET THE CORRECT E BANK IN CASE THIS IS 22006 LXCH BB # SWITCHED ERRASIBLE 50000 NDX A # GET THE TIME INDIRECTLY 30001 CA 1 22006 LXCH BB # RESTORE THE BB AND GOLOC 22706 LXCH GOLOC +1 13550 TCF FINDTIME # FIND OUT WHEN IT SHOULD BEGIN # ***** YOU MAY RETURN TO SWITCHED FIXED ***** SETLOC RESTART BANK COUNT* $$/RSROU D45">056729,000104: 01,3550 40000 FINDTIME COM # MAKE NEGITIVE SINCE IT WILL BE SUBTRACTD 54001 TS L # AND SAVE 50155 NDX TEMP2G 41247 CS TBASE1 00006 EXTEND 60025 SU TIME1 10000 CCS A 40000 COM 67663 AD OCT37776 65001 AD ONE 60001 AD L 10000 CCS A 35003 -3 CAF ZERO 13567 TCF +2 13567 TCF +1 445">056744,000119: 01,3567 65001 IMEDIATE AD ONE 00704 TC GOLOC -1 542">056746,000121: 01,3571 33534 ITSLIKEB CA RTRNCADR # TYPE B, SO STORE RETURN IN 54157 TS TEMPSWCH # TEMPSWCH IN CASE OF AN EVEN PHASE 33141 CA PRT2CADR # SET UP EXIT TO GET TABLE PART OF THIS 54707 TS GOLOC +2 # VARIABLE TYPE OF PHASE 30154 CA TEMPPHS # MAKE THE PHASE LOOK RIGHT FOR THE TABLE 76043 MASK OCT177 # PART OF THIS VARIABLE PHASE 54154 TS TEMPPHS 00006 EXTEND 50155 NDX TEMP2G # OBTAIN THE JOB:S 2CADR 31437 DCA PHSNAME1 52706 DXCH GOLOC 2">056761,000136: 01,3604 50155 ITSAJOB NDX TEMP2G # NOW ADD THE PRIORITY AND LET:S GO 31250 CA PHSPRDT1 143">056763,000138: 01,3606 54704 CHKNOVAC TS GOLOC -1 # SAVE PRIO UNTIL WE SEE IF ITS 00006 EXTEND # A FINDVAC OR A NOVAC 63614 BZMF ITSNOVAC 33514 CAF FVACCADR # POSITIVE, SET UP FINDVAC CALL. 56704 XCH GOLOC -1 # PICK UP PRIO, 00704 TC GOLOC -1 # AND GO 143">056771,000146: 01,3614 35323 ITSNOVAC CAF NOVACADR # NEGATIVE, 56704 XCH GOLOC -1 # SET UP NOVAC CALL, 40000 COM # CORRECT PRIO, 00704 TC GOLOC -1 # AND GO C">056776,000151: 01,3620 54020 ITSATBL TS CYR # FIND OUT IF THE PHASE IS ODD OR EVEN 10020 CCS CYR 13623 TCF +1 # IT:S EVEN 13721 TCF ITSEVEN 33534 CA RTRNCADR # IN CASE THIS IS THE SECOND PART OF A 54707 TS GOLOC +2 # TYPE B RESTART, WE NEED PROPER EXIT 30154 CA TEMPPHS # SET UP POINTER FOR FINDING OUR PLACE IN 54021 TS SR # THE RESTART TABLES 60021 AD SR 50155 NDX TEMP2G 62001 AD SIZETAB +1 54156 TS POINTER 2">056791,000166: 01,3634 00006 CONTBL2 EXTEND # FIND OUT WHAT:S IN THE TABLE 50156 NDX POINTER 32002 DCA CADRTAB # GET THE 2CADR 22706 LXCH GOLOC +1 # STORE THE BB INFORMATION 10000 CCS A # IS IT A JOB OR IS IT TIMED 24000 INCR A # POSITIVE, MUST BE A JOB 13715 TCF ITSAJOB2 24000 INCR A # MUST BE EITHER A WAITLIST OR LONGCALL 54705 TS GOLOC # LET-S STORE THE CORRECT CADR 33471 CA WTLTCADR # SET UP OUR EXIT TO WAITLIST 54704 TS GOLOC -1 30706 CA GOLOC +1 # NOW FIND OUT IF IT IS A WAITLIST CALL 74770 MASK BIT10 # THIS SHOULD BE ONE IF WE HAVE -BB 10000 CCS A # FOR THAT MATTER SO SHOULD BE BITS 9,8,7, # 6,5, AND LAST BUT NOT LEAST (PERHAPS NOT # IN IMPORTANCE ANYWAY. BIT 4 13710 TCF ITSWTLST # IT IS A WAITLIST CALL 50156 NDX POINTER # OBTAIN THE ORIGINAL DELTA T 32000 CA PRDTTAB # ADDRESS FOR THIS LONGCALL 15512 TCF ITSLGCL1 # NOW GO GET THE DELTA TIME # ***** THIS MUST BE IN FIXED FIXED ***** SETLOC FFTAG2 BANK COUNT* $$/RSROU C31">056825,000200: 5512 22706 ITSLGCL1 LXCH GOLOC +1 # OBTAIN THE CORRECT E BANK 22006 LXCH BB 22706 LXCH GOLOC +1 # AND PRESERVE OUR E AND F BANKS 00006 EXTEND # GET THE DELTA TIME 50000 NDX A 30001 DCA 0 22706 LXCH GOLOC +1 # RESTORE OUR E AND F BANK 22006 LXCH BB # RESTORE THE TASKS E AND F BANKS 22706 LXCH GOLOC +1 # AND PRESERVE OUR L 13656 TCF ITSLGCL2 # NOW LET:S PROCESS THIS LONGCALL # ***** YOU MAY RETURN TO SWITCHED FIXED ***** SETLOC RESTART BANK COUNT* $$/RSROU C32">056844,000219: 01,3656 53275 ITSLGCL2 DXCH LONGTIME 00006 EXTEND # CALCULATE TIME LEFT 40025 DCS TIME2 21275 DAS LONGTIME 00006 EXTEND 31273 DCA LONGBASE 21275 DAS LONGTIME 11274 CCS LONGTIME # FIND OUT HOW THIS SHOULD BE RESTARTED 13676 TCF LONGCLCL 13671 TCF +2 13564 TCF IMEDIATE -3 11275 CCS LONGTIME +1 13676 TCF LONGCLCL 13674 NOOP # CAN:T GET HERE ********* 13564 TCF IMEDIATE -3 13567 TCF IMEDIATE 34C">056863,000238: 01,3676 33145 LONGCLCL CA LGCLCADR # WE WILL GO TO LONGCALL 54704 TS GOLOC -1 00006 EXTEND # PREPARE OUR ENTRY TO LONGCALL 31275 DCA LONGTIME 00704 TC GOLOC -1 34C">056870,000245: 01,3703 33471 ITSLNGCL CA WTLTCADR # ASSUME IT WILL GO TO WAITLIST 54704 TS GOLOC -1 50155 NDX TEMP2G 41250 CS PHSPRDT1 # GET THE DELTA T ADDRESS 15512 TCF ITSLGCL1 # NOW GET THE DELTA TIME 354">056878,000253: 01,3710 40706 ITSWTLST CS GOLOC +1 # CORRECT THE BBCON INFORMATION 54706 TS GOLOC +1 50156 NDX POINTER # GET THE DT AND FIND OUT IF IT WAS STORED 32000 CA PRDTTAB # DIRECTLY OR INDIRECTLY 13543 TCF TIMETEST # FIND OUT HOW THE TIME IS STORED 232">056886,000261: 01,3715 56705 ITSAJOB2 XCH GOLOC # STORE THE CADR 50156 NDX POINTER # ADD THE PRIORITY AND LET:S GO 32000 CA PRDTTAB 13606 TCF CHKNOVAC E">056893,000268: 01,3721 30157 ITSEVEN CA TEMPSWCH # SET UP FOR EITHER THE SECOND PART OF THE 54707 TS GOLOC +2 # TABLE, OR A RETURN FOR THE NEXT GROUP 50155 NDX TEMP2G # SET UP POINTER FOR OUR LOCATION WITHIN 32000 CA SIZETAB # THE TABLE 60154 AD TEMPPHS # THIS MAY LOOK BAD BUT LET:S SEE YOU DO 60154 AD TEMPPHS # BETTER IN TIME OR NUMBERR OF LOCATIONS 60154 AD TEMPPHS 54156 TS POINTER 13634 TCF CONTBL2 # NOW PROCESS WHAT IS IN THE TABLE 432">056905,000280: 01,3732 36214 PHSPART2 CA THREE # SET THE POINTER FOR THE SECOND HALF OF 26156 ADS POINTER # THE TABLE 33534 CA RTRNCADR # THIS WILL BE OUR LAST TIME THROUGH THE 54707 TS GOLOC +2 # EVEN TABLE, SO AFTER IT GET THE NEXT # GROUP 13634 TCF CONTBL2 # SO LET:S GET THE SECOND ENTRY IN THE TBL 3">056913,000288: 01,3737 0154 TEMPPHS EQUALS MPAC >056914,000289: 01,3737 0155 TEMP2G EQUALS MPAC +1 2">056915,000290: 01,3737 0156 POINTER EQUALS MPAC +2 348">056916,000291: 01,3737 0157 TEMPSWCH EQUALS MPAC +3 >056917,000292: 01,3737 7701 MINUS2 EQUALS NEG2 >056918,000293: 01,3737 6043 OCT177 EQUALS LOW7 RESTARTS_ROUTINE.agc. Parent file is MAIN.agc