# Copyright: Public domain. # Filename: TVCRESTARTS.agc # Purpose: Part of the source code for Colossus 2A, AKA Comanche 055. # It is part of the source code for the Command Module's (CM) # Apollo Guidance Computer (AGC), for Apollo 11. # Assembler: yaYUL # Contact: Ron Burkey <info@sandroid.org>. # Website: www.ibiblio.org/apollo. # Pages: 956-960 # Mod history: 2009-05-13 RSB Adapted from the Colossus249/ file of the # same name, using Comanche055 page images. # 2009-05-20 RSB Corrections: TCF -> BZF in one place. # 2009-05-21 RSB In PHSCHK2, CS TVCPHASE corrected to # CCS TVCPHASE and CCS 4 corrected to CCS A. # Page 924 corrected to 961. CORCOPY +2 # corrected to CORCOPY +1. # # This source code has been transcribed or otherwise adapted from digitized # images of a hardcopy from the MIT Museum. The digitization was performed # by Paul Fjeld, and arranged for by Deborah Douglas of the Museum. Many # thanks to both. The images (with suitable reduction in storage size and # consequent reduction in image quality as well) are available online at # www.ibiblio.org/apollo. If for some reason you find that the images are # illegible, contact me at info@sandroid.org about getting access to the # (much) higher-quality images which Paul actually created. # # Notations on the hardcopy document read, in part: # # Assemble revision 055 of AGC program Comanche by NASA # 2021113-051. 10:28 APR. 1, 1969 # # This AGC program shall also be referred to as # Colossus 2A
# Page 956 # NAME....TVCRESTART PACKAGE, CONSISTING OF REDOTVC, ENABL1, 2, CMDSOUT, PHSCHK2, ETC. # LOG SECTION...TVCRESTARTS SUBROUTINE....DAPCSM # MODIFIED BY SCHLUNDT 21 OCTOBER 1968 # FUNCTIONAL DESCRIPTION.... # # *RESTART-PROOFS THE TVC DAPS, INCLUDING PITCHDAP, YAWDAP, # TVCEXECUTIVE, ROLLDAP, TVCINIT4, TVCDAPON, AND CSM/LM V46 SWTCHOVR. # *TVC RESTARTS DESERVE SPECIAL CONSIDERATION IN SEVERAL AREAS. # RESTART DOWN-TIME IS IMPORTANT BECAUSE OF THE TRANSIENTS INTRODUCED # BY THE THRUST VECTOR RETURN TO THE ACTUATOR MECHANICAL NULLS # FOLLOWING TVC- AND OPTICS-ERROR-COUNTER-DISENABLES (CHANNEL 12). # TVC USES A MIXTURE OF WAITLIST, T5, T6, AND JOB CALLS. THERE IS # FILTER MEMORY (UP TO 6TH ORDER) TO BE PROTECTED IF WILD TRANSIENTS # ARE TO BE AVOIDED. COUNTERS ARE INVOLVED FOR ONE-SHOT # CORRECTIONS AND GAIN UPDATES. THE GIMBAL TRIM ESTIMATORS AND THE # BODY AXIS ATTITUDE ERROR INTEGRATORS INVOLVE DIGITAL SUMMATION. # DIGITAL DIFFERENTIATORS ARE INVOLVED IN THE BODY AXIS RATE ESTIMA- # TIONS AND IN THE OUTPUTTING OF ACTUATOR COMMANDS. THERE IS AN # OFFSET-TRACKER-FILTER TO PROTECT. ETC., ETC. # *THOSE QUANTITIES WHICH MUST BE PROTECTED ARE STORED IN TEMPORARY # REGISTERS AS THEY ARE COMPUTED, FOR UPDATING THE REAL REGISTERS # DURING COPYCYCLES. # *THE SEVERAL COPYCYCLES ARE EACH PROTECTED BY PHASE POINTS AT THEIR # BEGINNING AND AT THEIR TERMINATION. THE PHASE POINTS ARE SIMPLY # ..INCR.. INSTRUCTIONS, EITHER ..INCR TVCEXPHS.. FOR COPYCYCLES # IN THE TVCEXECUTIVE, OR ..INCR TVCPHASE.. FOR THE PITCH AND YAW # COPYCYCLES. INDEXING ON EACH OF THESE POINTERS THEN PERMITS A # RETURN TO THE APPROPRIATE RESTART POINTS. # *IF A RESTART OCCURS DURING EITHER COPYCYCLE, THAT COPYCYCLE IS # COMPLETED. THEN THE NORMAL TVCINIT4....DAPINIT....PITCHDAP STARTUP # SEQUENCE IS CALLED UPON TO GET THINGS GOING AGAIN. # *TVC-ENABLE AND OPTICS-ERROR-COUNTER ENABLE MUST BE SET ASAP # (ALLOWING FOR PROCEDURAL DELAYS). THEN THE ENGINES ARE COMMANDED # TO THE P,YACTOFF TRIM VALUES. THE DAPS ARE THEN READY TO GO ON THE # AIR, WITH THE REGULAR STARTUP SEQUENCE, EITHER AT MRCLEAN FOR A # COMPLETE INITIALIZATION OR AT TVCINIT4 FOR A PARTIAL INITIALIZATION # *FOR RESTARTS PRIOR TO THE SETTING OF THE T5 BITS AT DOTVCON THE # PRE40.6 SECTION OF S40.6 TAKES CARE OF RE-ESTABLISHING TRIMS. # *IF A RESTART OCCURS DURING THE TVCEXEC....TVCEXFIN SEQUENCE THE # COMPUTATIONS WILL BE COMPLETED, STARTING AT THE APPROPRIATE RESTART # POINT, AFTER THE DAPS ARE READY TO GO ON THE AIR. # *IF A RESTART OCCURS PRIOR TO TVCINIT4 (TVCPHASE = -1) E.G. DURING # THE EARLY DAP INITIALIZATION PHASE, THE DAP STARTUP SEQUENCE IS # ENTERED AT MRCLEAN FOR A FULL INITIALIZATION. # *FOR RESTARTS DURING CSM/LM V46 SWITCH-OVER, TVCPHASE IS SET TO -2, # AND THE RESTART LOGIC GOES BACK TO REDO SWITCH-OVER (AFTER THE # NORMAL DAP RESTART SEQUENCE IS FOLLOWED). # *RESTARTS ARE NOT CRITICAL TO THE ROLL DAP PERFORMANCES HENCE THE # ROLL DAP IS MERELY RESTARTED. # *RESTARTS DURING A STROKE TEST (STROKER IS NON-ZERO) WILL CAUSE THE # Page 957 # STROKE TEST TO BE TERMINATED. A NEW V68 ENTRY WILL BE REQUIRED # TO GET IT GOING AGAIN (NO AUTOMATIC RESTART). # *REDOTVC IS REACHED FOLLOWING ANY RESTART WHICH FINDS THE T5 BITS # (BITS 15,14 OF FLAGWRD6) SET FOR TVC. DOTVCON SETS TVCPHASE = -1 # AND TVC EXPHS = 0 JUST BEFORE SETTING THESE BITS, JUST BEFORE # MAKING THE T5 CALL TO TVCDAPON. ON A NORMAL SHUTDOWN DOTVCRCS # CALLS RCSDAPON, WHICH RESETS THE T5 BIT FOR RCS. # CALLING SEQUENCE....T5, IN PARTICULAR BY ELRSKIP OF FRESH START/RESTART # # NORMAL EXIT MODES....RESUME, NOQRSM, POSTJUMP (TO TVCINIT4 OR MRCLEAN) # # ALARM OR ABORT EXIT MODES....NONE # # SUBROUTINES CALLED.... # # *PCOPY+1, YCOPY+1 (PITCH AND YAW COPYCYCLES) # *ENABLE1,2, CMDSOUT (RE-ESTABLISH ACTUATOR TRIMS) # *MRCLEAN OR TVCINIT4 (TVCDAP INITIALIZATIONS) # *SWICHOVR +5 (CSM/LM V46 SWITCH-OVER) # *EXRSTRT AND TVCEXECUTIVE PHASE POINTS 1 THRU 6 # *WAITLIST, IBNKCALL, POSTJUMP, ISWCALL # # OTHER INTERFACES....DOTVCON AND RCSDAPON (T5 BITS), ELRSKIP (CALLS IT) # ERASABLE INITIALIZATION REQUIRED.... # # *T5 BITS (1,0), TVCPHASE (-2,-1,0,1,2,3), TVCEXPHS (1 THRU 6) # *TVC DAP VARIABLES # *OPERATIONS PERFORMED BY REDOTVC ARE BASED ON THE ASSUMPTION THAT # THE TVC DAPS ARE RUNNING NORMALLY # # OUTPUT.... # # *PITCH AND YAW TVC DAP COPYCYCLES COMPLETED IF INTERUPTED # *TVCEXECUTIVE COMPLETED IF INTERUPTED # *STROKE TEST TERMINATED IF INTERRUPTED # *CSM/LM V46 SWITCH-OVER REPEATED IF INTERRUPTED # *ACTUATOR TRIMS RE-ESTABLISHED (ACTUATORS BACK ON THE AIR) # *TVC DAP INITIALIZATION AS REQUIRED # *ALL TVC DAP OPERATIONS ON THE AIR # # DEBRIS....TVC TEMPORARIES IN EBANK6
# Page 958
BANK16 SETLOC DAPROLL BANK EBANK= TVCPHASE COUNT* $$/RSRT
EXECPHS CCS TVCEXPHS # CHECK TVCEXECUTIVE PHASE TCF +2# MUST RESTART TVCEXECUTIVE TCF TVCDAPHS # NO NEED TO RESTART TVCEXECUTIVE
CAF NINE # 9CS DELAY TO FORCE EXRSTRT TO OCCUR TC WAITLIST # BEFORE PITCHDAP, AFTER CMDSOUT EBANK= TVCEXPHS 2CADR EXRSTRT
TVCDAPHS CS OCT37776 # CHECK BITS 15 AND 1 OF TVCPHASE TO SEE MASK TVCPHASE # DAP RESTART LOCATION (-1,1,2,3) CCS A TCF FINCOPY # FINISH THE COPYCYCLE FIRST TCF ENABL1 # JUST PREPARE THE OUTCOUNTERS AND GO
CS TVCPHASE # TEST FOR TVCPHASE = -2 MASK BIT2 # (THIS INDICATES RESTART OCCURRED EXTEND# DURING CSM/LM V46 SWITCH-OVER) BZF TRIM/CMD # NO. TVCPHASE = -1. RSTRT WAS IN TVCINIT
ENABL1 CAF BIT8 # TVC ENABLE, FOLLOWED BY 40 MS (MIN) WAIT AD BIT11 # SET BIT FOR OPTICS-DAC-ENABLE ALSO EXTEND# (ENABL1 ENTERED FROM TVCDAPHS / FINCOPY) WOR CHAN12 CAF TVCADDR # WAIT. CALLING ENABL2 (BBCON THERE) TS T5LOC CAF TVCADDR +4# 60 MS (TVCEXADR) TS TIME5
TCF RESUME
ENABL2 LXCH BANKRUPT # CONTINUE PREPARATION OF OUTCOUNTERS
PHSCHK2 CCS TVCPHASE # CHECK TVCPHASE AGAIN TCF CHKSTRK TCF CHKSTRK CCS A # A CONTAINS THE DIMINISHED ABSOLUTE OF TC +3# TVCPHASE (-2 BECOMES +1, -1 BECOMES +0)
TC POSTJUMP # REPEAT TVC INITIALIZATION CADR MRCLEAN # (DO NOT RETURN)
+3TC IBNKCALL # REPEAT CSM/LM V46 SWITCH-OVER CADR SWICHOVR +5# (RETURN TO CHECK FOR STROKE TEST)
CHKSTRK CCS STROKER # CHECK FOR STROKE TEST IN PROGRESS TCF TSTINITJ # YES, KILL IT TCF +2# NO, PROCEED TCF TSTINITJ # YES, KILL IT
+4TC POSTJUMP # IF POSITIVE OR ZERO, RESTART AT CADR TVCINIT4 # TVCINIT4 (ZEROS TVCPHASE, AND # CALLS TVC DAPS VIA DAPINIT)
FINCOPY INDEX TVCPHASE # PICK UP THE APPROPRIATE COPYCYCLE CAF TVCCADR
TCR ISWCALL # RE-ENTER THE COPYCYCLE, RETURN AT END TCF ENABL1 # NOW PREPARE THE OUTCOUNTERS
TRIM/CMD EXTEND# TVCDAPON INITIALIZATION NOT COMPLETED, # Page 960 DCA PACTOFF # EG. P,YCMD MAY NOT BE SET. SET... DXCH PCMD TCF ENABL1 # NOW PREPARE THE OUTCOUNTERS
TSTINITJ CAF ZERO # DISABLE STROKE TEST (-0 SHOWS PRIOR V68) TS STROKER # (+0 MEANS NEW V68 REQUIRED FOR STARTUP)
TCF CHKSTRK +4
EXRSTRT INDEX TVCEXPHS # TVCEXECUTIVE RESTARTS....GO TO CAF TVCEXADR # APPROPRIATE RESTART POINT INDEX A TCF0
# TVC RESTART TABLES.... ORDER IS REQUIRED. HI-ORDER WORDS ONLY, OF 2CADRS, SINCE BBCON IS ALREADY THERE.
