Pre-launch Review
WAITLIST
Scanned pages: 1117-1132
# Copyright: Public domain.# Filename: WAITLIST.agc# Purpose: Part of the source code for Luminary 1A build 099.# It is part of the source code for the Lunar Module's (LM)# Apollo Guidance Computer (AGC), for Apollo 11.# Assembler: yaYUL# Contact: Ron Burkey <info@sandroid.org>.# Website: www.ibiblio.org/apollo.# Pages: 1117-1132# Mod history: 2009-05-25 RSB Adapted from the corresponding# Luminary131 file, using page# images from Luminary 1A.# 2011-01-06 JL Fixed pseudo-label indentation.# 2011-05-07 JL Removed workarounds.## 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 001 of AGC program LMY99 by NASA 2021112-061# 16:27 JULY 14, 1969
# Page 1117# PROGRAM DESCRIPTION DATE -- 10 OCTOBER 1966# MOD NO -- 2 LOG SECTION -- WAITLIST# MOD BY -- MILLER (DTMAX INCREASED TO 162.5 SEC) ASSEMBLY -- SUNBURST REV 5# MOD 3 BY KERNAN (INHINT INSERTED AT WAITLIST) 2/28/68 SKIPPER REV 4# MOD 4 BY KERNAN (TWIDDLE IN 54) 3/28/68 SKIPPER REV 13.## FUNCTIONAL DESCRIPTION --# PART OF A SECTION OF PROGRAMS -- WAITLIST, TASKOVER, T3RUPT, USED TO CALL A PROGRAM (CALLED A TASK),# WHICH IS TO BEGIN IN C(A) CENTISECONDS. WAITLIST UPDATES TIME3, LST1, AND LST2. THE MEANING OF THESE LISTS# FOLLOW.## C(TIME3) = 16384 -(T1-T) CENTISECONDS, (T=PRESENT TIME, T1-TIME FOR TASK1)## C(LST1) = -(T2-T1)+1# C(LST1 +1) = -(T3-T2)+1# C(LST1 +2) = -(T4-T3)+1# ...# C(LST1 +6) = -(T8-T7)+1# C(LST1 +7) = -(T9-T8)+1## C(LST2) = 2CADR OF TASK1# C(LST2 +2) = 2CADR OF TASK2# ...# C(LST2 +14) = 2CADR OF TASK8# C(LST2 +16) = 2CADR OF TASK9## WARNINGS --# 1) 1 <= C(A) <= 16250D (1 CENTISECOND TO 162.5 SEC)# 2) 9 TASKS MAXIMUM# 3) TASKS CALLED UNDER INTERRUPT INHIBITED# 4) TASKS END BY TC TASKOVER## CALLING SEQUENCE --# L-1 CA DELTAT (TIME IN CENTISECONDS TO TASK START)# L TC WAITLIST# L+1 2CADR DESIRED TASK.# L+2 (MINOR OF 2CADR)# L+3 RELINT (RETURNS HERE)## TWIDDLE --# TWIDDLE IS FOR USE WHEN THE TASK BEING SET UP IS IN THE SAME EBANK AND FBANK AS THE USER. IN# SUCH CASES, IT IMPROVES UPON WAITLIST BY ELIMINATING THE NEED FOR THE BBCON HALF OF THE 2CADR,# Page 1118# SAVING A WORD. TWIDDLE IS LIKE WAITLIST IN EVERY RESPECT EXCEPT CALLING SEQUENCE, TO WIT,# L-1 CA DELTAT# L TC TWIDDLE# L+1 ADRES DESIRED TASK# L+2 RELINT (RETURNS HERE)## NORMAL EXIT MODES --# AT L+3 OF CALLING SEQUENCE.## ALARM OR ABORT EXIT MODES --# TC ABORT# OCT 1203 (WAITLIST OVERFLOW -- TOO MANY TASKS)## ERASABLE INITIALIZATION REQUIRED --# ACCOMPLISHED BY FRESH START -- LST2, ..., LST2 +16 = ENDTASK# LST1, ..., LST1 +7 = NEG1/2## OUTPUT --# LST1 AND LST2 UPDATED WTIH NEW TASK AND ASSOCIATED TIME.## DEBRIS --# CENTRALS -- A,Q,L# OTHER -- WAITEXIT, WAITADR, WAITTEMP, WAITBANK## DETAILED ANALYSIS OF TIMING --# CONTROL WILL NOT BE RETURNED TO THE SPECIFIED ADDRESS (2CADR) IN EXACTLY DELTA T CENTISECONDS.# THE APPROXIMATE TIME MAY BE CALCULATED AS FOLLOWS:# LET T0 = THE TIME OF THE TC WAITLIST# LET TS = T0 +147U + COUNTER INCREMENTS (SET UP TIME)# LET X = TS -(100TS)/100 (VARIANCE FROM COUNTERS)# LET Y = LENGTH OF TIME OF INHIBIT INTERRUPT AFTER T3RUPT# LET Z = LENGTH OF TIME TO PROCESS TASKS WHICH ARE DUE THIS T3RUPT BUT DISPATCHED EARLIER.# (Z=0, USUALLY).# LET DELTD = THE ACTUAL TIME TAKEN TO GIVE CONTROL TO 2CADR# THEN DELTD = TS+DELTA T -X +Y +Z +1.05MS* +COUNTERS*# *THE TIME TAKEN BY WAITLIST ITSELF AND THE COUNTER TICKING DURING THIS WAITLIST TIME.# IN SHORT, THE ACTUAL TIME TO RETURN CONTROL TO A 2CADR IS AUGMENTED BY THE TIME TO SET UP THE TASK'S# INTERRUPT, ALL COUNTERS TICKING, THE T3RUPT PROCESSING TIME, THE WAITLIST PROCESSING TIME AND THE POSSIBILITY# OF OTHER TASKS INHIBITING THE INTERRUPT.
BLOCK 02# Page 1119 EBANK= LST1 # TASK LISTS IN SWITCHED E BANK.
COUNT* $$/WAITTWIDDLE INHINT TS L # SAVE DELAY TIME IN L CA POSMAX ADS Q # CREATING OVERFLOW AND Q-1 IN Q CA BBANK EXTEND ROR SUPERBNK XCH L
WAITLIST INHINT XCH Q # SAVE DELTA T IN Q AND RETURN IN TS WAITEXIT # WAITEXIT. EXTEND INDEX WAITEXIT # IF TWIDDLING, THE TS SKIPS TO HERE DCA 0 # PICK UP 2CADR OF TASK. -1 TS WAITADR # BBCON WILL REMAIN IN LDLY2 CAF WAITBB # ENTRY FROM FIXDELAY AND VARDELAY. XCH BBANK TCF WAIT2
# RETURN TO CALLER AFTER TASK INSERTION:
LVWTLIST DXCH WAITEXIT AD TWO DTCB
EBANK= LST1WAITBB BBCON WAIT2
# RETURN TO CALLER +2 AFTER WAITING DT SPECIFIED AT CALLER +1.
FIXDELAY INDEX Q # BOTH ROUTINES MUST BE CALLED UNDER CAF 0 # WAITLIST CONTROL AND TERMINATE THE TASK INCR Q # IN WHICH THEY WERE CALLED.
# RETURN TO CALLER +1 AFTER WAITING THE DT AS ARRIVING IN A.
VARDELAY XCH Q # DT TO Q. TASK ADRES TO WAITADR. TS WAITADR CA BBANK # BBANK IS SAVED DURING DELAY. EXTEND ROR SUPERBNK # ADD SBANK TO BBCON. TS L CAF DELAYEX TS WAITEXIT # GO TO TASKOVER AFTER TASK ENTRY. TCF DLY2
# Page 1120DELAYEX TCF TASKOVER -2 # RETURNS TO TASKOVER.
# Page 1121# ENDTASK MUST ENTERED IN FIXED-FIXED SO IT IS DISTINGUISHABLE BY ITS ADRES ALONE.
EBANK= LST1ENDTASK -2CADR SVCT3
SVCT3 CCS FLAGWRD2 # DRIFT FLAG TCF TASKOVER TCF TASKOVER TCF +1
CKIMUSE CCS IMUCADR # DON'T DO NBDONLY IF SOMEONE ELSE IS IN TCF SVCT3X # IMUSTALL. TCF +3 TCF SVCT3X TCF SVCT3X
+3 CAF PRIO35 # COMPENSATE FOR NBD COEFFICIENTS ONLY. TC NOVAC # ENABLE EVERY 81.93 SECONDS EBANK= NBDX 2CADR NBDONLY
TCF TASKOVER
SVCT3X TC FIXDELAY # DELAY MAX OF 2 TIMES FOR IMUZERO. DEC 500 TC SVCT3 # CHECK DRIFT FLAG AGAIN.
# Page 1122# BEGIN TASK INSERTION.
BANK 01 COUNT* $$/WAITWAIT2 TS WAITBANK # BBANK OF CALLING PROGRAM. CA Q EXTEND BZMF WAITPOOH
CS TIME3 AD BIT8 # BIT 8 = OCT 200 CCS A # TEST 200 - C(TIME3). IF POSITIVE, # IT MEANS THAT TIME3 OVERFLOW HAS OCCURRED PRIOR TO CS TIME3 AND THAT # C(TIME3) = T - T1, INSTEAD OF 1.0 - (T1 - T). THE FOLLOWING FOUR # ORDERS SET C(A) = TD - T1 + 1 IN EITHER CASE.
AD OCT40001 # OVERFLOW HAS OCCURRED. SET C(A) = CS A # T - T1 + 1.0 - 201
# NORMAL CASE (C(A) NNZ) YIELDS SAME C(A): -( -(1.0-(T1-T)) + 200) - 1
AD OCT40201 AD Q # RESULT = TD - T1 + 1.
CCS A # TEST TD - T1 + 1.
AD LST1 # IF TD - T1 POS, GO TO WTLST5 WITH TCF WTLST5 # C(A) = (TD - T1) + C(LST1) = TD-T2+1
NOOP CS Q
# NOTE THAT THIS PROGRAM SECTION IS NEVER ENTERED WHEN T-T1 G/E -1,# SINCE TD-T1+1 = (TD-T) + (T-T1+1), AND DELTA T = TD-T G/E +1. (G/E# SYMBOL MEANS GREATER THAN OR EQUAL TO). THUS THERE NEED BE NO CON-# CERN OVER A PREVIOUS OR IMMINENT OVEFLOW OF TIME3 HERE.
AD POS1/2 # WHEN TD IS NEXT, FORM QUANTITY AD POS1/2 # 1.0 - DELTA T = 1.0 - (TD - T) XCH TIME3 AD NEGMAX AD Q # 1.0 - DELTAT T NOW COMPLETE. EXTEND # ZERO INDEX Q. QXCH 7 # (ZQ)
# Page 1123WTLST4 XCH LST1 XCH LST1 +1 XCH LST1 +2 XCH LST1 +3 XCH LST1 +4 XCH LST1 +5 XCH LST1 +6 XCH LST1 +7
CA WAITADR # (MINOR PART OF TASK CADR HAS BEEN IN L.) INDEX Q TCF +1
DXCH LST2 DXCH LST2 +2 DXCH LST2 +4 DXCH LST2 +6 DXCH LST2 +8D DXCH LST2 +10D # AT END, CHECK THAT C(LST2 +10) IS STD DXCH LST2 +12D DXCH LST2 +14D DXCH LST2 +16D AD ENDTASK # END ITEM, AS CHECK FOR EXCEEDING # THE LENGTH OF THE LIST. EXTEND # DUMMY TASK ADRES SHOULD BE IN FIXED- BZF LVWTLIST # FIXED SO ITS ADRES ALONE DISTINGUISHES TCF WTABORT # IT.
# Page 1124WTLST5 CCS A # TEST TD - T2 + 1 AD LST1 +1 TCF +4 AD ONE TC WTLST2 OCT 1
+4 CCS A # TEST TD - T3 + 1 AD LST1 +2 TCF +4 AD ONE TC WTLST2 OCT 2
+4 CCS A # TEST TD - T4 + 1 AD LST1 +3 TCF +4 AD ONE TC WTLST2 OCT 3
+4 CCS A # TEST TD - T5 + 1 AD LST1 +4 TCF +4 AD ONE TC WTLST2 OCT 4
+4 CCS A # TEST TD - T6 + 1 AD LST1 +5 TCF +4 AD ONE TC WTLST2 OCT 5
+4 CCS A # TEST TD - T7 + 1 AD LST1 +6 TCF +4 AD ONE TC WTLST2 OCT 6
# Page 1125 +4 CCS A # TEST TD - T2 + 1 AD LST1 +7 TCF +4 AD ONE TC WTLST2 OCT 7
+4 CCS AWTABORT TC FILLED NOOP # CAN'T GET HERE AD ONE TC WTLST2 OCT 10
OCT40201 OCT 40201
# Page 1126FILLED DXCH WAITEXIT TC BAILOUT1 # NO ROOM IN THE INN OCT 01203
# Page 1127# THE ENTRY TC WTLST2 JUST PRECEDING OCT N IS FOR T LE TD LE T -1.# N N+1# (LE MEANS LESS THAN OR EQUAL TO). AT ENTRY, C(A) = -(TD - T + 1)# N+1# THE LST1 ENTRY -(T -T +1) IS TO BE REPLACED BY -(TD - T + 1), AND# N+1 N N# THE ENTRY -(T - TD + 1) IS TO BE INSERTED IMMEDIATELY FOLLOWING.# N+1
WTLST2 TS WAITTEMP # C(A) = -(TD - T + 1) INDEX Q CAF 0 TS Q # INDEX VALUE INTO Q.
CAF ONE AD WAITTEMP INDEX Q # C(A) = -(TD - T ) + 1. ADS LST1 -1 # N
CS WAITTEMP INDEX Q TCF WTLST4
# C(TIME3) = 1.0 - (T1 - T)## C(LST1) = - (T2 - T1) + 1# C(LST1+1) = - (T3 - T2) + 1# C(LST1+2) = - (T4 - T3) + 1# C(LST1+3) = - (T5 - T4) + 1# C(LST1+4) = - (T6 - T5) + 1## C(LST2) = 2CADR TASK1# C(LST2+2) = 2CADR TASK2# C(LST2+4) = 2CADR TASK3# C(LST2+6) = 2CADR TASK4# C(LST2+8) = 2CADR TASK5# C(LST2+10) = 2CADR TASK6
# Page 1128# ENTERS HERE ON T3 RUPT TO DISPATCH WAITLISTED TASK.
T3RUPT EXTEND ROR SUPERBNK # READ CURRENT SUPERBANK VALUE AND TS BANKRUPT # SAVE WITH E AND F BANK VALUES. EXTEND QXCH QRUPT
T3RUPT2 CAF NEG1/2 # DISPATCH WAITLIST TASK. XCH LST1 +7 XCH LST1 +6 XCH LST1 +5 XCH LST1 +4 # 1. MOVE UP LST1 CONTENTS, ENTERING XCH LST1 +3 # A VALUE OF 1/2 +1 AT THE BOTTOM XCH LST1 +2 # FOR T6-T5, CORRESPONDING TO THE XCH LST1 +1 # INTERVAL 81.91 SEC FOR ENDTASK. XCH LST1 AD POSMAX # 2. SET T3 = 1.0 - T2 - T USING LIST 1. ADS TIME3 # SO T3 WON'T TICK DURING UPDATE. TS RUPTAGN CS ZERO TS RUPTAGN # SETS RUPTAGN TO +1 ON OVERFLOW.
EXTEND # DISPATCH TASK. DCS ENDTASK DXCH LST2 +16D DXCH LST2 +14D DXCH LST2 +12D DXCH LST2 +10D DXCH LST2 +8D DXCH LST2 +6 DXCH LST2 +4 DXCH LST2 +2 DXCH LST2
XCH L EXTEND WRITE SUPERBNK # SET SUPERBANK FROM BBCON OF 2CADR XCH L # RESTORE TO L FOR DXCH Z. DTCB
# Page 1129# RETURN, AFTER EXECUTION OF T3 OVERFLOW TASK:
BLOCK 02 COUNT* $$/WAITTASKOVER CCS RUPTAGN # IF +1 RETURN TO T3RUPT, IF -0 RESUME. CAF WAITBB TS BBANK TCF T3RUPT2 # DISPATCH NEXT TASK IF IT WAS DUE.
CA BANKRUPT EXTEND WRITE SUPERBNK # RESTORE SUPERBANK BEFORE RESUME IS DONE
RESUME EXTEND QXCH QRUPTNOQRSM CA BANKRUPT XCH BBANKNOQBRSM DXCH ARUPT RELINT RESUME
# Page 1130# LONGCALL# PROGRAM DESCRIPTION DATE -- 17 MARCH 1967# PROGRAM WRITTEN BY W.H.VANDEVER LOG SECTION WAITLIST# MOD BY -- R. MELANSON TO ADD DOCUMENTATION ASSEMBLY SUNDISK REV. 100## FUNCTIONAL DESCRIPTION --# LONGCALL IS CALLED WITH THE DELTA TIME ARRIVING IN A,L SCALED AS TIME2,TIME1 WITH THE 2CADR OF THE TASK# IMMEDIATELY FOLLOWING THE TC LONGCALL. FOR EXAMPLE, IT MIGHT BE DONE AS FOLLOWS WHERE TIMELOC IS THE NAME OF# A DP REGISTER CONTAINING A DELTA TIME AND WHERE TASKTODO IS THE NAME OF THE LOCATION AT WHICH LONGCALL IS TO# START.# CALLING SEQUENCE --# EXTEND# DCA TIMELOC# TC LONGCALL# 2CADR TASKTODO# NORMAL EXIT MODE --# 1) TC WAITLIST# 2) DTCB (TC L+3 OF CALLING ROUTINE 1ST PASS THRU LONGCYCL)# 3) DTCB (TO TASKOVER ON SUBSEQUENT PASSES THRU LONGCYCL)# ALARM OR ABORT EXIT MODE --# NONE# OUTPUT --# LONGTIME AND LONGTIME+1 = DELTA TIME# LONGEXIT AND LONGEXIT+1 = RETURN 2CADR# LONGCADR AND LONGCADR+1 = TASK 2CADR# A = SINGLE PRECISION TIME FOR WAITLIST# ERASABLE INITIALIZATION --# A = MOST SIGNIFICANT PART OF DELTA TIME# L = LEAST SIGNIFICANT PART OF DELTA TIME# Q = ADDRESS OF 2CADR TASK VALUE# DEBRIS --# A,Q,L# LONGCADR AND LONGCADR+1# LONGEXIT AND LONGEXIT+1# LONGTIME AND LONGTIME+1# *** THE FOLLOWING IS TO BE IN FIXED-FIXED AND UNSWITCHED ERRASIBLE **
BLOCK 02 EBANK= LST1LONGCALL DXCH LONGTIME # OBTAIN THE DELTA TIME
EXTEND # OBTAIN THE 2CADR# Page 1131 NDX Q DCA 0 DXCH LONGCADR
EXTEND # NOW GO TO THE APPROPRIATE SWITCHED BANK DCA LGCL2CDR # FOR THE REST OF LONGCALL DTCB
EBANK= LST1LGCL2CDR 2CADR LNGCALL2
# *** THE FOLLOWING MAY BE IN A SWITCHED BANK, INCLUDING ITS ERASABLE ***
BANK 01 COUNT* $$/WAITLNGCALL2 LXCH LONGEXIT +1 # SAVE THE CORRECT BB FOR RETURN CA TWO # OBTAIN THE RETURN ADDRESS ADS Q TS LONGEXIT
CA LONGTIME # CHECK FOR LEGITIMATE DELTA-TIME CCS A TCF LONGCYCL # HI-ORDER OK --> ALL IS OK. TCF +2 # HI-ORDER ZERO --> CHECK LO-ORDER. TCF LONGPOOH # HI-ORDER NEG. --> NEG. DT +2 CA LONGTIME +1 # CHECK LO-ORDER FOR ZERO OR NEGATIVE. EXTEND BZMF LONGPOOH # BAD DELTA-TIME. ABORT
# *** WAITLIST TASK LONGCYCL ***
LONGCYCL EXTEND # CAN WE SUCCESFULLY TAKE ABOUT 1.25 DCS DPBIT14 # MINUTES OFF OF LONGTIME DAS LONGTIME
CCS LONGTIME +1 # THE REASONING BEHIND THIS PART IS TCF MUCHTIME # INVOLVED, TAKING INTO ACCOUNT THAT THE # WORDS MAY NOT BE SIGNED CORRECTED (DP # BASIC INSTRUCTIONS # DO NOT SIGN CORRECT) AND THAT WE SUBTRAC- # TED BIT14 (1 OVER HALF THE POS. VALUE # REPRESENTABLE IN SINGLE WORD) NOOP # CAN'T GET HERE ************* TCF +1 CCS LONGTIME TCF MUCHTIMEDPBIT14 OCT 00000 OCT 20000
# LONGCALL# Page 1132LASTTIME CA BIT14 # GET BACK THE CORRECT DELTA T FOR WAITLIST ADS LONGTIME +1 TC WAITLIST EBANK= LST1 2CADR GETCADR # THE ENTRY TO OUR LONGCADR
LONGRTRN CA TSKOVCDR # SET IT UP SO THAT ONLY THE FIRST EXIT IS DXCH LONGEXIT # TO THE CALLER OF LONGCALL DTCB # THE REST ARE TO TASKOVER
MUCHTIME CA BIT14 # WE HAVE OVER OUR ABOUT 1.25 MINUTES TC WAITLIST # SO SET UP FOR ANOTHER CYCLE THROUGH HERE EBANK= LST1 2CADR LONGCYCL
TCF LONGRTRN # NOW EXIT PROPERLY
# *** WAITLIST TASK GETCADR ***
GETCADR DXCH LONGCADR # GET THE LONGCALL THAT WE WISHED TO START DTCB # AND TRANSFER CONTROL TO IT
TSKOVCDR GENADR TASKOVERLONGPOOH DXCH LONGEXIT TCF +2WAITPOOH DXCH WAITEXIT +2 TC POODOO1 OCT 01204