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.
|
045422,000002: ## Copyright: Public domain.
045423,000003: ## Filename: INTER-BANK_COMMUNICATION.agc
045424,000004: ## Purpose: A section of Skylark revision 048.
045425,000005: ## It is part of the source code for the Apollo Guidance Computer (AGC)
045426,000006: ## for Skylab-2, Skylab-3, Skylab-4, and ASTP. No original listings of
045427,000007: ## this software are available; instead, this file was created via
045428,000008: ## disassembly of dumps of the core rope modules actually flown on
045429,000009: ## Skylab-2. Access to these modules was provided by the New Mexico
045430,000010: ## Museum of Space History.
045431,000011: ## Assembler: yaYUL
045432,000012: ## Contact: Ron Burkey <info@sandroid.org>.
045433,000013: ## Website: www.ibiblio.org/apollo/index.html
045434,000014: ## Mod history: 2023-09-04 MAS Created from Artemis 072.
045435,000015:
045436,000016:
045437,000017: # THE FOLLOWING ROUTINE CAN BE USED TO CALL A SUBROUTINE IN ANOTHER BANK. IN THE BANKCALL VERSION, THE
045438,000018: # CADR OF THE SUBROUTINE IMMEDIATELY FOLLOWS THE TC BANKCALL INSTRUCTION, WITH C(A) AND C(L) PRESERVED.
045439,000019:
045440,000020: 4000 SETLOC FFTAG1
045441,000021: 4000 BANK
045442,000022:
045443,000023: 4647 COUNT* $$/BANK
045444,000024: 4647 52134 BANKCALL DXCH BUF2 # SAVE INCOMING A,L.
045445,000025: 4650 50002 INDEX Q # PICK UP CADR.
045446,000026: 4651 30000 CA 0
045447,000027: 4652 24002 -1 INCR Q # SO WE RETURN TO THE LOC. AFTER THE CADR.
045448,000028:
045449,000029: # SWCALL IS IDENTICAL TO BANKCALL, EXCEPT THAT THE CADR ARRIVES IN A.
045450,000030:
045451,000031: 4653 54001 SWCALL TS L
045452,000032: 4654 22004 LXCH FBANK # SWITCH BANKS, SAVING RETURN.
045453,000033: 4655 75053 MASK LOW10 # GET SUB-ADDRESS OF CADR.
045454,000034: 4656 56002 XCH Q # A,L NOW CONTAINS DP RETURN.
045455,000035: 4657 52134 DXCH BUF2 # RESTORING INPUTS IF THIS IS A BANKCALL.
045456,000036: 4660 50002 INDEX Q
045457,000037: 4661 02000 TC 10000 # SETTING Q TO SWRETURN.
045458,000038:
045459,000039: 4662 56134 SWRETURN XCH BUF2 +1 # COMES HERE TO RETURN TO CALLER. C(A,L)
045460,000040: 4663 56004 XCH FBANK # ARE PRESERVED FOR RETURN.
045461,000041: 4664 56134 XCH BUF2 +1
045462,000042: 4665 00133 TC BUF2
045463,000043:
045464,000044: # THE FOLLOWING ROUTINE CAN BE USED AS A UNILATERAL JUMP WITH C(A,L) PRESERVED AND THE CADR IMMEDIATELY
045465,000045: # FOLLOWING THE TC POSTJUMP INSTRUCTION.
045466,000046:
045467,000047: 4666 56002 POSTJUMP XCH Q # SAVE INCOMING C(A).
045468,000048: 4667 50000 INDEX A # GET CADR.
045469,000049: 4670 30000 CA 0
045470,000050:
045471,000051: # BANKJUMP IS THE SAME AS POSTJUMP, EXCEPT THAT THE CADR ARRIVES IN A.
045472,000052:
045473,000053: 4671 54004 BANKJUMP TS FBANK
045474,000054: 4672 75053 MASK LOW10
045475,000055: 4673 56002 XCH Q # RESTORING INPUT C(A) IF THIS WAS A
045476,000056: 4674 50002 Q+10000 INDEX Q # POSTJUMP.
045477,000057: 4675 12000 PRIO12 TCF 10000 # PRIO12 = TCF 10000 = 12000
045478,000058:
045479,000059:
045480,000060: # THE FOLLOWING ROUTINE GETS THE RETURN CADR SAVED BY SWCALL OR BANKCALL AND LEAVES IT IN A.
045481,000061:
045482,000062: 4676 35053 MAKECADR CAF LOW10
045483,000063: 4677 70133 MASK BUF2
045484,000064: 4700 60134 AD BUF2 +1
045485,000065: 4701 00002 TC Q
045486,000066:
045487,000067: 4702 54135 SUPDACAL TS MPTEMP
045488,000068: 4703 56004 XCH FBANK # SET FBANK FOR DATA.
045489,000069: 4704 00006 EXTEND
045490,000070: 4705 04007 ROR SUPERBNK # SAVE FBANK IN BITS 15-11, AND
045491,000071: 4706 56135 XCH MPTEMP # SUPERBANK IN BITS 7-5.
045492,000072: 4707 75053 MASK LOW10
045493,000073: 4710 56001 XCH L # SAVE REL. ADR. IN BANK, FETCH SUPERBITS.
045494,000074: 4711 00004 INHINT # BECAUSE RUPT DOES NOT SAVE SUPERBANK.
045495,000075: 4712 00006 EXTEND
045496,000076: 4713 01007 WRITE SUPERBNK # SET SUPERBANK FOR DATA.
045497,000077: 4714 50001 INDEX L
045498,000078: 4715 32000 CA 10000 # PINBALL (FIX MEM DISP) PREVENTS DCA HERE
045499,000079: 4716 56135 XCH MPTEMP # SAVE 1ST WD, FETCH OLD FBANK AND SBANK.
045500,000080: 4717 00006 EXTEND
045501,000081: 4720 01007 WRITE SUPERBNK # RESTORE SUPERBANK.
045502,000082: 4721 00003 RELINT
045503,000083: 4722 54004 TS FBANK # RESTORE FBANK.
045504,000084: 4723 30135 CA MPTEMP # RECOVER FIRST WORD OF DATA.
045505,000085: 4724 00002 RETURN # 24 WDS. DATACALL 516 MU, SUPDACAL 432 MU
045506,000086:
045507,000087:
045508,000088: # THE FOLLOWING ROUTINES ARE IDENTICAL TO BANKCALL AND SWCALL EXCEPT THAT THEY ARE USED IN INTERRUPT.
045509,000089:
045510,000090: 4725 52073 IBNKCALL DXCH RUPTREG3 # USES RUPTREG3,4 FOR DP RETURN ADDRESS.
045511,000091: 4726 50002 INDEX Q
045512,000092: 4727 30000 CAF 0
045513,000093: 4730 24002 INCR Q
045514,000094:
045515,000095: 4731 54001 ISWCALL TS L
045516,000096: 4732 22004 LXCH FBANK
045517,000097: 4733 75053 MASK LOW10
045518,000098: 4734 56002 XCH Q
045519,000099: 4735 52073 DXCH RUPTREG3
045520,000100: 4736 50002 INDEX Q
045521,000101: 4737 02000 TC 10000
045522,000102:
045523,000103: 4740 56073 ISWRETRN XCH RUPTREG4
045524,000104: 4741 56004 XCH FBANK
045525,000105: 4742 56073 XCH RUPTREG4
045526,000106: 4743 00072 TC RUPTREG3
045527,000107:
045528,000108: # 2. USPRCADR ACCESSES INTERPRETIVE CODING IN OTHER THAN THE USER'S FBANK. THE CALLING SEQUENCE IS AS FOLLOWS:
045529,000109:
045530,000110: # L TC USPRCADR
045531,000111: # L+1 CADR INTPRETX INTPRETX IS THE INTERPRETIVE CODING
045532,000112: # RETURN IS TO L+2
045533,000113:
045534,000114: 4744 54164 USPRCADR TS LOC # SAVE A
045535,000115: 4745 34772 CA BIT8
045536,000116: 4746 54023 TS EDOP # EXIT INSTRUCTION TO EDOP
045537,000117: 4747 30006 CA BBANK
045538,000118: 4750 54165 TS BANKSET # USER'S BBANK TO BANKSET
045539,000119: 4751 50002 INDEX Q
045540,000120: 4752 30000 CA 0
045541,000121: 4753 54004 TS FBANK # INTERPRETIVE BANK TO FBANK
045542,000122: 4754 75053 MASK LOW10 # YIELDS INTERPRETIVE RELATIVE ADDRESS
045543,000123: 4755 56002 XCH Q # INTERPRETIVE ADDRESS TO Q, FETCHING L+1
045544,000124: 4756 56164 XCH LOC # L+1 TO LOC, RETRIEVING ORIGINAL A
045545,000125: 4757 14674 TCF Q+10000
045546,000126:
045547,000127:
045548,000128: # THERE ARE FOUR POSSIBLE SETTINGS FOR CHANNEL 07. (CHANNEL 07 CONTAINS THE SUPERBANK SETTING.)
045549,000129:
045550,000130: # PSEUDO-FIXED OCTAL PSEUDO
045551,000131: # SUPERBANK SETTING S-REG. VALUE BANK NUMBERS ADDRESSES
045552,000132: # ---------- ------- ------------ ------------ ------------
045553,000133: # SUPERBANK 3 0XX 2000 - 3777 30 - 37 70000 - 107777 (WHERE XX CAN BE ANYTHING AND
045554,000134: # WILL USUALLY BE SEEN AS 11)
045555,000135: # SUPERBANK 4 100 2000 - 3777 40 - 47 110000 - 127777 (AS FAR AS IT CAN BE SEEN,
045556,000136: # ONLY BANKS 40-43 WILL EVER BE
045557,000137: # AND ARE PRESENTLY AVAILABLE)
045558,000138: # SUPERBANK 5 101 2000 - 3777 50 - 57 130000 - 147777 (PRESENTLY NOT AVAILABLE TO
045559,000139: # THE USER)
045560,000140: # SUPERBANK 6 110 2000 - 3777 60 - 67 150000 - 167777 (PRESENTLY NOT AVAILABLE TO
045561,000141: # THE USER)
045562,000142:
End of include-file INTER-BANK_COMMUNICATION.agc. Parent file is MAIN.agc