Pre-launch Review
WAITLIST
Scanned pages: 1221-1235
# Copyright: Public domain.# Filename: WAITLIST.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: 1221-1235# Mod history: 2009-05-14 RSB Adapted 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 1221# 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 4BY 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 1222# 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 WITH 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 1223 EBANK= LST1 # TASK LISTS IN SWITCHED E BANK.
COUNT 02/WAIT
TWIDDLE 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 EXTEND BZMF WATLST0- 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
WATLST0- TC POODOO OCT 1204 # WAITLIST CALL WITH ZERO OR NEG DT
# 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# Page 1224 ROR SUPERBNK # ADD SBANK TO BBCON. TS L CAF DELAYEX TS WAITEXIT # GO TO TASKOVER AFTER TASK ENTRY. TCF DLY2
DELAYEX TCF TASKOVER -2 # RETURNS TO TASKOVER
# Page 1225# 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
CCS IMUCADR # DON'T DO NBDONLY IF SOMEONE ELSE IS IN TCF SVCT3X 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
SETLOC FFTAG6 BANK
SVCT3X TC FIXDELAY # DELAY MAX OF 2 TIMES FOR IMU ZERO DEC 500 TC SVCT3 # CHECK DRIFT FLAG AGAIN
# Page 1226# BEGIN TASK INSERTION.
BANK 01 COUNT 01/WAIT
WAIT2 TS WAITBANK # BBANK OF CALLING PROGRAM. 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 OVERFLOW 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 1227WTLST4 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 1228WTLST5 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 1229 +4 CCS A AD LST1 +7 TCF +4 AD ONE TC WTLST2 OCT 7
+4 CCS AWTABORT TC BAILOUT # NO ROOM IN THE INN. OCT 1203
AD ONE TC WTLST2 OCT 10
OCT40201 OCT 40201
# Page 1230# THE ENTRY TO 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
# Page 1231# 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 WONT 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 1232# RETURN, AFTER EXECUTION OF T3 OVERFLOW TASK:
BLOCK 02 COUNT 02/WAIT
TASKOVER 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 1233# 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 1234 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 01/WAIT
LNGCALL2 LXCH LONGEXIT +1 # SAVE THE CORRECT BB FOR RETURN CA TWO # OBTAIN THE RETURN ADDRESS ADS Q TS LONGEXIT
# *** 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
# LONGCALLLASTTIME CA BIT14 # GET BACK THE CORRECT DELTA TFOR 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# Page 1235 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 TASKOVER