Pre-launch Review
POWERED FLIGHT SUBROUTINES
Scanned pages: 1365-1372
# Copyright: Public domain.# Filename: POWERED_FLIGHT_SUBROUTINES.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: 1365-1372# Mod history: 2009-05-10 SN (Sergio Navarro). Started adapting# from the Colossus249/ file of the same# name, using Comanche055 page images.## 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 1365 BANK 14 # SAME FBANK AS THE FINDCDUD SUB-PROGRAM SETLOC POWFLITE BANK
EBANK= DEXDEX COUNT* $$/POWFL
# CDUTRIG, CDUTRIG1, CDUTRIG2, AND CD*GR*GS ALL COMPUTE THE SINES AND# COSINES OF THREE 2'S COMPLEMENT ANGLES AND PLACE THE RESULT, DOUBLE# PRECISION, IN THE SAME ORDER AS THE INPUTS, AT SINCDU AND COSCDU. AN# ADDITIONAL OUTPUT IS THE 1'S COMPLEMENT ANGLES AT CDUSPOT. THESE# ROUTINES GO OUT OF THEIR WAY TO LEAVE THE MPAC AREA AS THEY FIND IT,# EXCEPT FOR THE GENERALLY UNIMPORTANT MPAC +2. THEY DIFFER ONLY IN# WHERE THEY GET THE ANGLES, AND IN METHOD OF CALLING.
# CDUTRIG (AND CDUTRIG1, WHICH CAN BE CALLED IN BASIC) COMPUTE THE# SINES AND COSINES FROM THE CURRENT CONTENTS OF THE CDU REGISTERS.# THE CONTENTS OF CDUTEMP, ETC., ARE NOT TOUCHED SO THAT THEY MAY# CONTINUE TO FORM A CONSISTENT SET WITH THE LATEST PIPA READINGS.
# CDUTRIG1 IS LIKE CDUTRIG EXCEPT THAT IT CAN BE CALLED IN BASIC.
# CD*TR*GS FINDS CDU VALUES IN CDUSPOT RATHER THAN IN CDUTEMP. THIS# ALLOWS USERS TO MAKE TRANSFORMATIONS USING ARBITRARY ANGLES, OR REAL# ANGLES IN AN ORDER OTHER THAN X Y Z. A CALL TO THIS ROUTINE IS# NECESSARY IN PREPARATION FOR A CALL TO AX*SR*T IN EITHER OF ITS TWO# MODES (SMNB OR NBSM). SINCE AX*SR*T EXPECTS TO FIND THE SINES AND# COSINES IN THE ORDER Y Z X THE ANGLES MUST HAVE BEEN PLACED IN CDUSPOT# IN THIS ORDER. CD*TR*GS NEED NOT BE REPEATED WHEN AX*SR*T IS CALLED# MORE THAN ONCE, PROVIDED THE ANGLES HAVE NOT CHANGED. NOTE THAT SINCE# IT CLOBBERS BUF2 (IN THE SINE AND COSINE ROUTINES) CD*TR*GS CANNOT BE# CALLED USING BANKCALL. SORRY.
# CD*TR*G IS LIKE CD*TR*GS EXCEPT THAT IT CAN BE CALLED IN# INTERPRETIVE.
CDUTRIG EXIT TC CDUTRIGS TC INTPRET RVQ
CD*TR*G EXIT TC CD*TR*GS TC INTPRET RVQ
CDUTRIGS CA CDUX TS CDUSPOT +4 CA CDUY TS CDUSPOT# Page 1366 CA CDUZ TS CDUSPOT +2
CD*TR*GS EXTEND QXCH TEM2 CAF FOURTR*GL**P MASK SIX # MAKE IT EVEN AND SMALLER TS TEM3 INDEX TEM3 CA CDUSPOT DXCH MPAC # STORING 2'S COMP ANGLE, LOADING MPAC DXCH VBUF +4 # STORING MPAC FOR LATER RESTORATION TC USPRCADR CADR CDULOGIC EXTEND DCA MPAC INDEX TEM3 DXCH CDUSPOT # STORING 1'S COMPLEMENT ANGLE TC USPRCADR CADR COSINE DXCH MPAC INDEX TEM3 DXCH COSCDU # STORING COSINE EXTEND INDEX TEM3 DCA CDUSPOT # LOADING 1'S COMPLEMENT ANGLE TC USPRCADR CADR SINE +1 # SINE +1 EXPECTS ARGUMENT IN A AND L DXCH VBUF +4 # BRINGING UP PRIOR MPAC TO BE RESTORED DXCH MPAC INDEX TEM3 DXCH SINCDU CCS TEM3 TCF TR*GL**P TC TEM2# Page 1367# *******************************************************************************************************
# QUICTRIG, INTENDED FOR GUIDANCE CYCLE USE WHERE TIME IS CRITICAL, IS A MUCH FASTER VERSION OF CD*TR*GS.# QUICTRIG COMPUTES AND STORES THE SINES AND COSINES OF THE 2'S COMPLEMENT ANGLES AT CDUSPOT, CDUSPOT +2,# AND CDUSPOT +4. UNLIKE CD*TR*GS, QUICTRIG DOES NOT LEAVE THE 1'S COMPLEMENT VERSIONS OF THE ANGLES IN# CDUSPOT. QUICTRIG'S EXECUTION TIME IS 4.1 MS; THIS IS 10 TIMES AS FAST AS CD*TR*GS. QUICTRIG MAY BE# CALLED FROM INTERPRETIVE AS AN RTB OP-CODE, OR FROM BASIC VIA BANKCALL OR IBNKCALL.
QUICTRIG INHINT # INHINT SINCE DAP USES THE SAME TEMPS EXTEND QXCH ITEMP1 CAF FOUR +4 MASK SIX TS ITEMP2 INDEX ITEMP2 CA CDUSPOT TC SPSIN EXTEND MP BIT14 # SCALE DOWN TO MATCH INTERPRETER OUTPUTS INDEX ITEMP2 DXCH SINCDU INDEX ITEMP2 CA CDUSPOT TC SPCOS EXTEND MP BIT14 INDEX ITEMP2 DXCH COSCDU CCS ITEMP2 TCF QUICTRIG +4 CA ITEMP1 RELINT TC A# Page 1368#****************************************************************************
# THESE INTERFACE ROUTINES MAKE IT POSSIBLE TO CALL AX*SR*T, ETC., IN# INTERPRETIVE. LATER, WHERE POSSIBLE, THEY WILL BE ELIMINATED.## NBSM WILL BE THE FIRST TO GO. IT SHOULD NOT BE USED.
NBSM STQ X2 LXC,1 VLOAD* S1 # BASE ADDRESS OF THE CDU ANGLES IS IN S1 0,1 STOVL CDUSPOT 32D # VECTOR TO BE TRANSFORMED IS IN 32D CALL TRG*NBSM STCALL 32D # SINCE THERE'S NO STGOTO X2
# THESE INTERFACE ROUTINES ARE PERMANENT. ALL RESTORE USER'S EBANK# SETTING. ALL ARE STRICT INTERPRETIVE SUBROUTINES, CALLED USING "CALL",# RETURNING VIA QPRET. ALL EXPECT AND RETURN THE VECTOR TO BE TRANSFOR-# MED INTERPRETER-STYLE IN MPAC; COMPONENTS AT MPAC, MPAC +3, AND MPAC +5.
# TRG*SMNB AND TRG*NBSM BOTH EXPECT TO SEE THE 2'S COMPLEMENT ANGLES# AT CDUSPOT (ORDER Y Z X, AT CDUSPOT, CDUSPOT +2, AND CDUSPOT +4; ODD# LOCATIONS NEED NOT BE ZEROED). TRG*NBSM DOES THE NB TO SM TRANSFOR-# MATION; TRG*SMNB, VICE VERSA.
# CDU*NBSM DOES ITS TRANSFORMATION USING THE PRESENT CONTENTS OF# THE CDL COUNTERS. OTHERWISE IT IS LIKE TRG*NBSM.## CDU*SMNB IS THE COMPLEMENT OF CDU*NBSM.
CDU*SMNB EXIT TC CDUTRIGS TCF C*MM*N1
TRG*SMNB EXIT TC CD*TR*GSC*MM*N1 TC MPACVBUF # AX*SR*T EXPECTS VECTOR IN VBUF CS THREE # SIGNAL FOR SM TO NB TRANSFORMATION.C*MM*N2 TC AX*SR*T TC INTPRET VLOAD RVQ VBUF
CDU*NBSM EXIT TC CDUTRIGS
# Page 1369
TCF C*MM*N3
TRG*NBSM EXIT TC CD*TR*GSC*MM*N3 TC MPACVBUF # FOR AX*SR*T CA THREE # SIGNAL FOR NB TO SM TRANSFORMATION TCF C*MM*N2
# *NBSM* AND *SMNB* EXPECT TO SEE THE SINES AND COSINES (AT SINCDU# AND COSCDU) RATHER THAN THE ANGLES THEMSELVES. OTHERWISE THEY ARE# LIKE TRG*NBSM AND TRG*SMNB.
# NOTE THAT JUST AS CD*TR*GS NEED BE CALLED ONLY ONCE FOR EACH SERIES# OF TRANSFORMATIONS USING THE SAME ANGLES, SO TOO ONLY ONE OF TRG*NBSM# AND TRG*SMNB NEED BE CALLED FOR EACH SERIES. FOR SUBSEQUENT TRANFOR-# MATIONS USE *NBSM* AND *SMNB*.
*SMNB* EXIT TCF C*MM*N1
*NBSM* EXIT TCF C*MM*N3
# AX*SR*T COMBINES THE OLD SMNB AND NBSM. FOR THE NB TO SM# TRANSFORMATION, ENTER WITH +3 IN A. FOR SM TO NB, ENTER WITH -3.# THE VECTOR TO BE TRANSFORMED ARRIVES, AND IS RETURNED, IN VBUF.# AX*SR*T EXPECTS TO FIND THE SINES AND COSINES OF THE ANGLES OF ROTATION# AT SINCDU AND COSCDU, IN THE ORDER Y Z X. A CALL TO CD*TR*GS, WITH# THE 2'S COMPLEMENT ANGLES (ORDER Y Z X) AT CDUSPOT, WILL TAKE CARE OF# THIS. HERE IS A SAMPLE CALLING SEQUENCE:-
# TC CDUTRIGS# CS THREE ("CA THREE" FOR NBSM)# TC AX*SR*T
# THE CALL TO CD*TR*GS NEED NOT BE REPEATED, WHEN AX*SR*T IS CALLED MORE# THAN ONCE, UNLESS THE ANGLES HAVE CHANGED.
# AX*SR*T IS GUARANTEED SAFE ONLY FOR VECTORS OF MAGNITUDE LESS THAN# UNITY. A LOOK AT THE CASE IN WHICH A VECTOR OF GREATER MAGNITUDE# HAPPENS TO LIE ALONG AN AXIS OF THE SYSTEM TO WHICH IT IS TO BE TRANS-# FORMED CONVINCES ONE THAT THIS IS A RESTRICTION WHICH MUST BE ACCEPTED.
AX*SR*T TS DEXDEX # WHERE IT BECOMES THE INDEX OF INDEXES EXTEND QXCH RTNSAVER
R*TL**P CCS DEXDEX # +3 --> 0 -3 --> 2 CS DEXDEX # THUS: +2 --> 1 -2 --> 1 AD THREE # +1 --> 2 -1 --> 0# Page 1370 EXTEND INDEX A DCA INDEXI DXCH DEXI
CA ONE TS BUF EXTEND INDEX DEX1 DCS VBUF TCF LOOP1 # REALLY BE A SUBTRACT, AND VICE VERSA
LOOP2 DXCH BUF # LOADING VECTOR COMPONENT, STORING INDEX
LOOP1 DXCH MPAC CA SINESLOC AD DEX1 TS ADDRWD
TC DMPSUB # MULTIPLY BY SIN(CDUANGLE) CCS DEXDEX DXCH MPAC # NBSM CASE TCF +3 EXTEND # SMNB CASE DCS MPAC DXCH TERM1TMP
CA SIX # SINCDU AND COSCDU (EACH 6 WORDS) MUST ADS ADDRWD # BE CONSECUTIVE AND IN THAT ORDER
EXTEND INDEX BUF INDEX DEX1 DCA VBUF DXCH MPAC TC DMPSUB # MULTIPLY BY COS(CDUANGLE) DXCH MPAC DAS TERM1TMP DXCH TERM1TMP DDOUBL INDEX BUF INDEX DEX1 DXCH VBUF DXCH BUF # LOADING INDEX, STORING VECTOR COMPONENT
CCS A # 'CAUSE THAT'S WHERE THE INDEX NOW IS TCF LOOP2
EXTEND DIM DEXDEX # DECREMENT MAGNITUDE PRESERVING SIGN
# Page 1371TSTPOINT CCS DEXDEX # ONLY THE BRANCHING FUNCTION IS USED TCF R*TL**P TC RTNSAVER TCF R*TL**P TC RTNSAVER
SINESLOC ADRES SINCDU # FOR USE IN SETTING ADDRWD
INDEXI DEC 4 # ********** DON'T *********** DEC 2 # ********** TOUCH *********** DEC 0 # ********** THESE *********** DEC 4 # ********** CONSTANTS ***********
# ******************************************************************************# Page 1372# THIS SUBROUTINE COMPUTES INCREMENTAL CHANGES IN CDU(GIMBAL) ANGLES FROM INCREMENTAL CHANGES ABOUT SM AXES. IT# REQUIRES SM INCREMENTS AS A DP VECTOR SCALED AT ONE REVOLUTION(DTHETASM,+2,+4). SIN,COS(CDUY,Z,X) ARE IN# SINCDU,+2,+4 AND COSCDU,+2,+4 RESPECTIVELY,SCALED TO ONE HALF. CDU INCREENTS ARE PLACED IN DCDU,+2,+4 SCALED TO# ONE REVOLUTION.
# * COS(IGA)SEC(MGA) 0 -SIN(IGA)SEC(MGA) *# * *# * -COS(IGA)TAN(MGA) 1 SIN(IGA)TAN(MGA) *# * *# * SIN(IGA) 0 COS(IGA) *
BANK 14 SETLOC POWFLIT1 BANK
SMCDURES DLOAD DMP DTHETASM COSCDUY
PDDL DMP DTHETASM +4 SINCDUY
BDSU DDV COSCDUZ STORE DCDU
DMP SL1 # SCALE SINCDUZ BDSU
DTHETASM +2 STODL DCDU +2 DTHETASM
DMP PDDL SINCDUY DTHETASM +4
DMP DAD COSCDUY SL1 STORE DCDU +4 RVQ