### FILE="Main.annotation"
## Copyright:   Public domain.
## Filename:    AGS_INITIALIZATION.agc
## Purpose:     A section of LUM69 revision 2.
##              It is part of the reconstructed source code for the flown
##              version of the flight software for the Lunar Module's (LM)
##              Apollo Guidance Computer (AGC) for Apollo 10. The code has
##              been recreated from a copy of Luminary revsion 069, using
##              changes present in Luminary 099 which were described in
##              Luminary memos 75 and 78. The code has been adapted such
##              that the resulting bugger words exactly match those specified
##              for LUM69 revision 2 in NASA drawing 2021152B, which gives
##              relatively high confidence that the reconstruction is correct.
## Reference:   pp. 221-225
## Assembler:   yaYUL
## Contact:     Ron Burkey <info@sandroid.org>.
## Website:     www.ibiblio.org/apollo/index.html
## Mod history: 2019-07-27 MAS  Created from Luminary 69.

## Page 221

# PROGRAM NAME:   AGS INITIALIZATION (R47)

# WRITTEN BY  :   RHODE/KILROY/FOLLETT

# MOD NO. :       0
# DATE    :       23 MARCH 1967
# MOD BY  :       KILROY

# MOD NO. :       1
# DATE    :       28 OCTOBER 1967
# MOD BY  :       FOLLETT

# FUNCT. DESC.:   (1) TO PROVIDE THE AGS ABORT ELECTRONICS ASSEMBLY(AEA) WITH THE LEM AND CSM STATE VECTORS
#                 (POSITION,VELOCITY,TIME) IN LEM IMU COORDINATES BY MEANS OF THE LGC DIGITAL DOWNLINK.
#
#                 (2) TO ZERO THE ICDU, LGC AND AEA GIMBAL ANGLE COUNTERS SIMULTANEOUSLY IN ORDER TO ESTABLISH A
#                 COMMON ZERO REFERENCE FOR THE MEASUREMENT OF GIMBAL(EULER) ANGLES WHICH DEFINE LEM ATTITUDE
#                 (3) TO ESTABLISH THE GROUND ELAPSED TIME OF AEA CLOCK ZERO.(IF AN AEA CLOCK ZERO IS
#                 REQUESTED DURING THIS PROGRAM

# LOG SECTION :   AGS INITIALIZATION

# CALLING SEQ :   PROGRAM IS ENTERED WHEN ASTRONAUT KEYS V47E ON DSKY.
#                 R47 MAY BE CALLED AT ANY TIME EXCEPT WHEN ANOTHER EXTENDED VERB IS IN PROGRESS

# SUBROUTINES
# CALLED      :
#
# NORMAL EXIT :   ENDEXT
#
# ALARM/ABORT :   ALARM - BAD REFSMMAT - CODE:220
#                 OPERATOR ERROR IF V47 SELECTED DURING ANOTHER EXTENDED VERB.
#
# ERASABLES
# USED        :   SAMPTIME    (2) TIME OF :ENTER: KEYSTROKE
#                 AGSK        (2) GROUND ELAPSED TIME OF THE AEA CLOCK :ZERO:
#                 AGSBUFF   (140) CONTAINS AGS INITIALIZATION DATA (SEE :OUTPUT: BELOW)
#                 AGSWORD     (1) PREVIOUS DOWNLIST SAVED HERE

                EBANK=          AGSBUFF

                BANK            40
                SETLOC          R47
                BANK

                COUNT*          $$/R47

AGSINIT         CAF             REFSMBIT
                MASK            FLAGWRD3                # CHECK REFSMFLG.
                CCS             A

## Page 222
                TC              REDSPTEM                # REFSMMAT IS OK
                TC              ALARM                   # REFSMMAT IS BAD
                OCT             220
                TC              ENDEXT

NEWAGS          EXTEND
                DCA             SAMPTIME                # TIME OF THE :ENTER: KEYSTROKE
                DXCH            AGSK                    # BECOMES NEW AEA CLOCK :ZERO:

REDSPTEM        EXTEND
                DCA             AGSK
                DXCH            DSPTEMX
AGSDISPK        CAF             V06N16
                TC              BANKCALL                # R1 = 00XXX. HRS., R2 = 000XX MIN.,
                CADR            GOMARKF                 # R3 = 0XX.XX SEC.
                TC              ENDEXT                  # TERMINATE RETURN
                TC              AGSVCALC                # PROCEED   RETURN
                CS              BIT6                    # IS ENTER VIA A V32
                AD              MPAC
                EXTEND
                BZF             NEWAGS                  # YES, USE KEYSTROKE TIME FOR NEW AGSK

                EXTEND                                  # NO, NEW AGSK LOADED VIA V25
                DCA             DSPTEMX                 # LOADED INTO DSPTEMX BY KEYING
                TC              REDSPTEM        -1      # V25E FOLLOWED BY HRS.,MINS.,SECS.
                                                        # DISPLAY THE NEW K

AGSVCALC        TC              INTPRET
                SET
                                NODOFLAG                # DONT ALLOW V37
                SET             EXIT
                                XDSPFLAG

                CAF             V06N16
                TC              BANKCALL
                CADR            EXDSPRET

                TC              INTPRET                 # EXTRAPOLATE LEM AND CSM STATE VECTORS
                RTB                                     # TO THE PRESENT TIME
                                LOADTIME                # LOAD MPAC WITH TIME2,TIME1
                STCALL          TDEC1                   # CALCULATE LEM STATE VECTOR
                                LEMPREC
                CALL                                    # CALL ROUTINE TO CONVERT TO SM COORDS AND
                                SCALEVEC                # PROVIDE PROPER SCALING
                STODL           AGSBUFF                 # (LEMPREC AND CSMPREC LEAVE TDEC1 IN TAT)
                                TAT                     # TAT = TIME TO WHICH RATT1 AND VATT1 ARE
                STCALL          TDEC1                   # COMPUTED(CSEC SINCE CLOCK START B-28).
                                CSMPREC                 # CALCULATE CSM STATE VECTOR FOR SAME TIME
                CALL
                                SCALEVEC

## Page 223
                STODL           AGSBUFF         +6
                                TAT
                DSU             DDV                     # CALCULATE AND STORE THE TIME
                                AGSK
                                TSCALE
                STORE           AGSBUFF         +12D
                EXIT

                CAF             LAGSLIST
                TS              DNLSTCOD

                CAF             20SEC                   # DELAY FOR 20 SEC WHILE THE AGS
                TC              BANKCALL                # DOWNLIST IS TRANSMITTED
                CADR            DELAYJOB

                CA              AGSWORD
                TS              DNLSTCOD                # RETURN TO THE OLD DOWNLIST
                CAF             IMUSEBIT
                MASK            FLAGWRD0                # CHECK IMUSE FLAG.
                CCS             A
                TC              AGSEND                  # IMU IS BEING USED - DO NOT ZERO
CKSTALL         CCS             IMUCADR                 # CHECK FOR IMU USAGE WHICH AVOIDS THE
                TCF             +3                      # IMUSE BIT:  I.E., IMU COMPENSATION.
                TCF             +6                      # FREE.  GO AHEAD WITH THE IMU ZERO.
                TCF             +1
   +3           CAF             TEN                     # WAIT .1 SEC AND TRY AGAIN.
                TC              BANKCALL
                CADR            DELAYJOB
                TCF             CKSTALL

   +6           TC              BANKCALL                # IMU IS NOT IN USE
                CADR            IMUZERO                 # SET IMU ZERO DISCRETE FOR 320MSECS
                TC              BANKCALL                # WAIT 3 SEC FOR COUNTERS TO INCREMENT
                CADR            IMUSTALL
                TC              AGSEND
AGSEND          TC              DOWNFLAG                # ALLOW V37
                ADRES           NODOFLAG

                CAF             V50N16
                TC              BANKCALL
                CADR            GOMARK3
                TCF             ENDEXT
                TCF             ENDEXT
                TC              ENDEXT

SCALEVEC        VLOAD           MXV
                                VATT1
                                REFSMMAT
                VXSC            VSL2
                                VSCALE

## Page 224
                VAD             VAD                     # THIS SECTION ROUNDS THE VECTOR, AND
                                AGSRND1                 # CORRECTS FOR THE FACT THAT THE AGS
                                AGSRND2                 # IS A 2 S COMPLIMENT MACHINE WHILE THE
                RTB                                     # LGC IS A 1 S COMPLIMENT MACHINE.
                                VECSGNAG
                STOVL           VATT1
                                RATT1
                MXV             VXSC
                                REFSMMAT
                                RSCALE
                VSL8            VAD                     # AGAIN THIS SECTION ROUNDS.  TWO VECTORS
                                AGSRND1                 # ARE ADDED TO DEFEAT ALSIGNAG IN THE
                VAD             RTB                     # CASE OF A HIGH-ORDER ZERO COUPLED WITH
                                AGSRND2                 # A LOW ORDER NEGATIVE PART.
                                VECSGNAG
                LXA,1
                                VATT1
                SXA,1           LXA,1
                                MPAC            +1
                                VATT1           +2
                SXA,1           LXA,1
                                MPAC            +4
                                VATT1           +4
                SXA,1           RVQ
                                MPAC            +6

LAGSLIST        =               ONE
V01N14          VN              0114
V50N00A         VN              5000
V00N25          EQUALS          OCT31
V06N16          VN              0616
V00N34          EQUALS          34DEC
V50N16          VN              5016
TSCALE          2DEC            100             B-10    # CSEC TO SEC SCALE FACTOR
20SEC           DEC             2000
RSCALE          2DEC            3.280839        B-3     # METERS TO FEET SCALE FACTOR
VSCALE          2DEC            3.280839        E2 B-9  # METERS/CS TO FEET/SEC SCALE FACTOR
AGSRND1         2OCT            0000060000
                2OCT            0000060000
                2OCT            0000060000
AGSRND2         2OCT            0000037777
                2OCT            0000037777

## Page 225
                2OCT            0000037777

                SBANK=          LOWSUPER                # FOR SUBSEQUENT LOW 2CADRS.