Pre-launch Review
IMU COMPENSATION PACKAGE
Scanned pages: 297-306
# Copyright: Public domain.# Filename: IMU_COMPENSATION_PACKAGE.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: 297-306# Mod history: 2009-05-08 RSB Adapted from the Colossus249/ file of the# same name, using Comanche055 page images/# 2009-05-21 RSB In IRIGZ, PRIO17 corrected to PRIO21.## 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 297 BANK 7 SETLOC IMUCOMP BANK EBANK= NBDX
COUNT 06/ICOMP
1/PIPA CAF LGCOMP # SAVE EBANK OF CALLING PROGRAM XCH EBANK TS MODE
CCS GCOMPSW # BYPASS IF GCOMPSW NEGATIVE TCF +3 TCF +2 TCF IRIG1 # RETURN
INHINT # ASSURE COMPLETE COMPENSATION OF DELV'S # FOR DOWNLINK.1/PIPA1 CAF FOUR # PIPAZ, PIPAY, PIPAX TS BUF +2
INDEX BUF +2 CA PIPASCF # (P.P.M.) X 2(-9) EXTEND INDEX BUF +2 MP DELVX # (PP) X 2(+14) NOW (PIPA PULSES) X 2(+5) TS Q # SAVE MAJOR PART
CA L # MINOR PART EXTEND MP BIT6 # SCALE 2(+9) SHIFT RIGHT 9 INDEX BUF +2 TS DELVX +1 # FRACTIONAL PIPA PULSES SCALED 2(+14)
CA Q # MAJOR PART EXTEND MP BIT6 # SCALE 2(+9) SHIFT RIGHT 9 INDEX BUF +2 DAS DELVX # (PIPAI) + (PIPAI)(SFE)
INDEX BUF +2 CS PIPABIAS # (PIPA PULSES)/(CS) X 2(-8) * EXTEND MP 1/PIPADT # (CS) X 2(+8) NOW (PIPA PULSES) X 2(+0) * EXTEND MP BIT1 # SCALE 2(+14) SHIFT RIGHT 14 * INDEX BUF +2 DAS DELVX # (PIPAI) + (PIPAI)(SFE) - (BIAS)(DELTAT)
CCS BUF +2 # PIPAZ, PIPAY, PIPAX# Page 298 AD NEG1 TCF 1/PIPA1 +1 NOOP # LESS THAN ZERO IMPOSSIBLE. RELINT# Page 299
IRIGCOMP TS GCOMPSW # INDICATE COMMANDS 2 PULSES OR LESS. TS BUF # INDEX COUNTER - IRIGX, IRIGY, IRIGZ.
IRIGX EXTEND DCS DELVX # (PIPA PULSES) X 2(+14) DXCH MPAC CA ADIAX # (GYRO PULSES)/(PIPA PULSE) X 2(-3) * TC GCOMPSUB # -(ADIAX)(PIPAX) (GYRO PULSES) X 2(+14)
EXTEND # DCS DELVY # (PIPA PULSES) X 2(+14) DXCH MPAC # CS ADSRAX # (GYRO PULSES)/(PIPA PULSE) X 2(-3) * TC GCOMPSUB # +(ADSRAX)(PIPAY) (GYRO PULSES) X 2(+14)
# EXTEND # ***# DCS DELVY # *** (PIPA PULSES) X 2(+14)# DXCH MPAC # ***# CA ADOAX # *** (GYRO PULSES)/(PIPA PULSE) X 2(-3) *# TC GCOMPSUB # *** -(ADOAX)(PIPAZ) (GYRO PULSES) X 2(+14)
CS NBDX # (GYRO PULSES)/(CS) X 2(-5) TC DRIFTSUB # -(NBDX)(DELTAT) (GYRO PULSES) X 2(+14)
IRIGY EXTEND DCS DELVY # (PIPA PULSES) X 2(+14) DXCH MPAC CA ADIAY # (GYRO PULSES)/(PIPA PULSE) X 2(-3) * TC GCOMPSUB # -(ADIAY)(PIPAY) (GYRO PULSES) X 2(+14)
EXTEND DCS DELVZ # (PIPA PULSES) X 2(+14) DXCH MPAC CS ADSRAY # (GYRO PULSES)/(PIPA PULSE) X 2(-3) * TC GCOMPSUB # +(ADSRAY)(PIPAZ) (GYRO PULSES) X 2(+14)
# EXTEND # ***# DCS DELVX # *** (PIPA PULSES) X 2(+14)# DXCH MPAC # ***# CA ADOAY # *** (GYRO PULSES)/(PIPA PULSE) X 2(-3) *# TC GCOMPSUB # *** -(ADOAY)(PIPAZ) (GYRO PULSES) X 2(+14)
CS NBDY # (GYRO PULSES)/(CS) X 2(-5) TC DRIFTSUB # -(NBDY)(DELTAT) (GYRO PULSES) X 2(+14)
IRIGZ EXTEND DCS DELVY # (PIPA PULSES) X 2(+14) DXCH MPAC CA ADSRAZ # (GYRO PULSES)/(PIPA PULSE) X 2(-3) *# Page 300 TC GCOMPSUB # -(ADSRAZ)(PIPAY) (GYRO PULSES) X 2(+14)
EXTEND DCS DELVZ # (PIPA PULSES) X 2(+14) DXCH MPAC CA ADIAZ # (GYRO PULSES)/(PIPA PULSE) X 2(-3) * TC GCOMPSUB # -(ADIAZ)(PIPAZ) (GYRO PULSES) X 2(+14)
# EXTEND # ***# DCS DELVX # *** (PIPA PULSE) X 2(+14)# DXCH MPAC # ***# CS ADOAZ # *** (GYRO PULSES)/(PIPA PULSE) X 2(-3) *# TC GCOMPSUB # *** +(ADOAZ)(PIPAX) (GYRO PULSES) X 2(+14)
CA NBDZ # (GYRO PULSES)/(CS) X 2(-5) TC DRIFTSUB # +(NBDZ)(DELTAT) (GYRO PULSES) X 2(+14)
# Page 301 CCS GCOMPSW # ARE GYRO COMMANDS GREATER THAN 2 PULSES TCF +2 # YES TCF IRIG1 # NO
CAF PRIO21 # HIGHER THAN SERVICER-LESS THAN PRELAUNCH TC NOVAC EBANK= NBDX 2CADR 1/GYRO
RELINTIRIG1 CA MODE # SET EBANK FOR RETURN TS EBANK TCF SWRETURN
GCOMPSUB XCH MPAC # ADIA OR ADSRA COEFFICIENT ARRIVES IN A EXTEND # C(MPAC) = (PIPA PULSES) X 2(+14) MP MPAC # (GYRO PULSES)/(PIPA PULSE) X 2(-3) * DXCH VBUF # NOW = (GYRO PULSES) X 2(+11) *
CA MPAC +1 # MINOR PART OF PIPA PULSES EXTEND MP MPAC # ADIA OR ADSRA TS L CAF ZERO DAS VBUF # NOW = (GYRO PULSES) X 2(+11) *
CA VBUF # PARTIAL RESULT - MAJOR EXTEND MP BIT12 # SCALE 2(+3) SHIFT RIGHT 3 * INDEX BUF # RESULT = (GYRO PULSES) X 2(+14) DAS GCOMP # HI(ADIA)(PIPAI) OR HI(ADSRA)(PIPAI)
CA VBUF +1 # PARTIAL RESULT - MINOR EXTEND MP BIT12 # SCALE 2(+3) SHIFT RIGHT 3 * TS L CAF ZERO INDEX BUF # RESULT = (GYRO PULSES) X 2(+14) DAS GCOMP # (ADIA)(PIPAI) OR (ADSRA)(PIPAI)
TC Q
# Page 302DRIFTSUB EXTEND QXCH BUF +1
EXTEND # C(A) = NBD (GYRO PULSES)/(CS) X 2(-5) MP 1/PIPADT # (CS) X 2(+8) NO (GYRO PULSES) X 2(+3) LXCH MPAC +1 # SAVE FOR FRACTIONAL COMPENSATION EXTEND MP BIT4 # SCALE 2(+11) SHIFT RIGHT 11 INDEX BUF DAS GCOMP # HI(NBD)(DELTAT) (GYRO PULSES) X 2(+14)
CA MPAC +1 # NOW MINOR PART EXTEND MP BIT4 # SCALE 2(+11) SHIFT RIGHT 11 TS L CAF ZERO INDEX BUF # ADD IN FRACTIONAL COMPENSATION DAS GCOMP # (NBD)(DELTAT) (GYRO PULSES) X 2(+14)
DRFTSUB2 CAF TWO # PIPAX, PIPAY, PIPAZ AD BUF XCH BUF INDEX A CCS GCOMP # ARE GYRO COMMANDS 1 PULSE OR GREATER TCF +2 # YES TC BUF +1 # NO
MASK NEGONE CCS A # ARE GYRO COMMANDS GREATER THAN 2 PULSES TS GCOMPSW # YES - SET GCOMPSW POSITIVE TC BUF +1 # NO
# Page 3031/GYRO CAF FOUR # PIPAZ, PIPAY, PIPAX TS BUF
INDEX BUF # SCALE GYRO COMMANDS FOR IMUPULSE CA GCOMP +1 # FRACTIONAL PULSES EXTEND MP BIT8 # SHIFT RIGHT 7 INDEX BUF TS GCOMP +1 # FRACTIONAL PULSES SCALED
CAF ZERO # SET GCOMP = 0 FOR DAS INSTRUCTION INDEX BUF XCH GCOMP # GYRO PULSES EXTEND MP BIT8 # SHIFT RIGHT 7 INDEX BUF DAS GCOMP # ADD THESE TO FRACTIONAL PULSES ABOVE
CCS BUF # PIPAZ, PIPAY, PIPAX AD NEG1 TCF 1/GYRO +1LGCOMP ECADR GCOMP # LESS THAN ZERO IMPOSSIBLE
CAF LGCOMP TC BANKCALL CADR IMUPULSE # CALL GYRO TORQUING ROUTINE TC BANKCALL CADR IMUSTALL # WAIT FOR PULSES TO GET OUT TCF ENDOFJOB # TEMPORARY
GCOMP1 CAF FOUR # PIPAZ, PIPAY, PIPAX TS BUF
INDEX BUF # RESCALE CA GCOMP +1 EXTEND MP BIT8 # SHIFT MINOR PART LEFT 7 - MAJOR PART = 0 INDEX BUF LXCH GCOMP +1 # BITS 8-14 OF MINOR PART WERE = 0
CCS BUF # PIPAZ, PIPAY, PIPAX AD NEG1 TCF GCOMP1 +1V06N30S VN 0630 TCF ENDOFJOB
# Page 304NBDONLY CCS GCOMPSW # BYPASS IF GCOMPSW NEGATIVE TCF +3 TCF +2 TCF ENDOFJOB
INHINT CCS FLAGWRD2 # PREREAD T3RUPT MAY COINCIDE TCF ENDOFJOB TCF ENDOFJOB TCF +1
CA TIME1 # (CS) X 2(+14) XCH 1/PIPADT # PREVIOUS TIME RELINT COM AD 1/PIPADTNBD2 CCS A # CALCULATE ELAPSED TIME AD ONE # NO TIME1 OVERFLOW TCF NBD3 # RESTORE TIME DIFFERENCE AND JUMP TCF +2 # TIME1 OVERFLOW TCF ENDOFJOB # IF ELAPSED TIME = 0 (DIFFERENCE = -0)
COM # CALCULATE ABSOLUTE DIFFERENCE AD POSMAX
NBD3 EXTEND # C(A) = DELTAT (CS) X 2(+14) MP BIT10 # SHIFT RIGHT 5 DXCH VBUF EXTEND DCA VBUF DXCH MPAC # DELTAT NOW SCALED (CS) X 2(+19)
CAF ZERO TS GCOMPSW # INDICATE COMMANDS 2 PULSES OR LESS TS BUF # PIPAX, PIPAY, PIPAZ
CS NBDX # (GYRO PULSES)/(CS) X 2(-5) TC FBIASSUB # -(NBOX)(DELTAT) (GYRO PULSES) X 2(+14)
EXTEND DCS VBUF DXCH MPAC # DELTAT SCALED (CS) X 2(+19) CA NBDY # (GYRO PULSES)/(CS) X 2(-5) TC FBIASSUB # -(NBDY)(DELTAT) (GYRO PULSES) X 2(+14)
EXTEND DCS VBUF DXCH MPAC # DELTAT SCALED (CS) X 2(+19) CS NBDZ # (GYRO PULSES)/(CS) X 2(-5) TC FBIASSUB # +(NBDZ)(DELTAT) (GYRO PULSES) X 2(+14)# Page 305 CCS GCOMPSW # ARE GYRO COMMANDS GREATER THAN 2 PULSES TCF 1/GYRO # YES TCF ENDOFJOB # NO
# Page 306FBIASSUB XCH Q TS BUF +1
CA Q # NBD SCALED (GYRO PULSES)/(CS) X 2(-5) EXTEND MP MPAC # DELTAT SCALED (CS) X 2(+19) INDEX BUF DAS GCOMP # HI(NBD)(DELTAT) (GYRO PULSES) X 2(+14)
CA Q # NO FRACTIONAL PART EXTEND MP MPAC +1 TS L CAF ZERO INDEX BUF DAS GCOMP # (NBD)(DELTAT) (GYRO PULSES) X 2(+14)
TCF DRFTSUB2 # CHECK MAGNITUDE OF COMPENSATION
LASTBIAS TC BANKCALL CADR PIPUSE
CCS GCOMPSW # BYPASS IF GCOMPSW NEGATIVE TCF +3 TCF +2 TCF ENDOFJOB
CAF PRIO31 # 2 SECONDS SCALED (CS) X 2(+8) XCH 1/PIPADT COM AD PIPTIME1 +1 # TIME AT PIPA1 =0 TCF NBD2