EXECUTIVE.s

# Copyright:	Public domain.
# Filename:	EXECUTIVE.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:	1208-1220
# 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 1208
		BLOCK	02

# TO ENTER A JOB REQUEST REQUIRING NO VAC AREA:

		COUNT	02/EXEC
		
NOVAC		INHINT
		AD	FAKEPRET	# LOC(MPAC +6) - LOC(QPRET)
		TS	NEWPRIO		# PRIORITY OF NEW JOB + NOVAC C(FIXLOC)

		EXTEND
		INDEX	Q		# Q WILL BE UNDISTURBED THROUGHOUT.
		DCA	0		# 2CADR OF JOB ENTERED.
		DXCH	NEWLOC
		CAF	EXECBANK
		XCH	FBANK
		TS	EXECTEM1
		TCF	NOVAC2		# ENTER EXECUTIVE BANK.

# TO ENTER A JOB REQUEST REQUIREING A VAC AREA -- E.G., ALL (PARTIALLY) INTERPRETIVE JOBS.

FINDVAC		INHINT
		TS	NEWPRIO
		EXTEND
		INDEX	Q
		DCA	0
SPVACIN		DXCH	NEWLOC
		CAF	EXECBANK
		XCH	FBANK
		TCF	FINDVAC2	# OFF TO EXECUTIVE SWITCHED-BANK.

# TO ENTER A FINDVAC WITH THE PRIORITY IN NEWPRIO TO THE 2CADR ARRIVING IN A AND L:
# USERS OF SPVAC MUST INHINT BEFORE STORING IN NEWPRIO.

SPVAC		XCH	Q
		AD	NEG2
		XCH	Q
		TCF	SPVACIN

# TO SUSPEND A BASIC JOB SO A HIGHER PRIORITY JOB MAY BE SERVICED:

CHANG1		LXCH	Q
		CAF	EXECBANK
		XCH	BBANK
		TCF	CHANJOB

# TO SUSPEND AN INTERPRETIVE JOB:

CHANG2		CS	LOC		# NEGATIVE LOC SHOWS JOB = INTERPRETIVE.
# ITRACE (4) REFERS TO "CHANG2"
# Page 1209
		TS	L
	+2	CAF	EXECBANK
 		TS	BBANK
		TCF	CHANJOB -1

# Page 1210
# TO VOLUNTARILY SUSPEND A JOB UNTIL THE COMPLETION OF SOME ANTICIPATED EVENT (I/O EVENT ETC.):

JOBSLEEP	TS	LOC
		CAF	EXECBANK
		TS	FBANK
		TCF	JOBSLP1

# TO AWAKEN A JOB PUT TO SLEEP IN THE ABOVE FASHION:

JOBWAKE		INHINT
		TS	NEWLOC
		CS	TWO		# EXIT IS VIA FINDVAC/NOVAC PROCEDURES.
		ADS	Q
		CAF	EXECBANK
		XCH	FBANK
		TCF	JOBWAKE2

# TO CHANGE THE PRIORITY OF A JOB CURRENTLY UNDER EXECUTION:

PRIOCHNG	INHINT			# NEW PRIORITY ARRIVES IN A.  RETURNS TO
		TS	NEWPRIO		# CALLER AS SOON AS NEW JOB PRIORITY IS
		CAF	EXECBANK	# HIGHEST.  PREPARE FOR POSSIBLE BASIC-
		XCH	BBANK		# STYLE CHANGE-JOB.
		TS	BANKSET
		CA	Q
		TCF	PRIOCH2

# TO REMOVE A JOB FROM EXECUTIVE CONSIDERATIONS:

ENDOFJOB	CAF	EXECBANK
		TS	FBANK
		TCF	ENDJOB1

ENDFIND		CA	EXECTEM1	# RETURN TO CALLER AFTER JOB ENTRY
		TS	FBANK		# COMPLETE.
		TCF	Q+2
EXECBANK	CADR	FINDVAC2

FAKEPRET	ADRES	MPAC -36D	# LOC(MPAC +6) - LOC(QPRET)

# Page 1211
# LOCATE AN AVAILABLE VAC AREA

		BANK	01
		COUNT	01/EXEC
		
FINDVAC2	TS	EXECTEM1	# (SAVE CALLER'S BANK FIRST.)
		CCS	VAC1USE
		TCF	VACFOUND
		CCS	VAC2USE
		TCF	VACFOUND
		CCS	VAC3USE
		TCF	VACFOUND
		CCS	VAC4USE
		TCF	VACFOUND
		CCS	VAC5USE
		TCF	VACFOUND
		TC	BAILOUT
		OCT	1201		# NO VAC AREAS.

VACFOUND	AD	TWO		# RESERVE THIS VAC AREA BY STORING A ZERO
		ZL			# IN ITS VAC USE REGISTER AND STORE THE
		INDEX	A		# ADDRESS OF THE FIRST WORD OF IT IN THE
		LXCH	0 	-1	# LOW NINE BITS OF THE PRIORITY WORD.
		ADS	NEWPRIO

NOVAC2		CAF	ZERO		# NOVAC ENTERS HERE.  FIND A CORE SET.
		TS	LOCCTR
		CAF	NO.CORES	# SEVEN SETS OF ELEVEN REGISTERS EACH.
NOVAC3		TS	EXECTEM2
		INDEX	LOCCTR
		CCS	PRIORITY	# EACH PRIORITY REGISTER CONTAINS -0 IF
		TCF	NEXTCORE	# THE CORESPONDING CORE SET IS AVAILABLE.
NO.CORES	DEC	6
		TCF	NEXTCORE	# AN ACTIVE JOB HAS A POSITIVE PRIORITY
					# BUT A DORMANT JOB'S PRIORITY IS NEGATIVE

# Page 1212
CORFOUND	CA	NEWPRIO		# SET THE PRIORITY OF THIS JOB IN THE CORE
		INDEX	LOCCTR		# SET'S PRIORITY REGISTER AND SET THE
		TS	PRIORITY	# JOB'S PUSH-DOWN POINTER AT THE BEGINNING
		MASK	LOW9		# OF THE WORK AREA AND OVERFLOW INDICATOR.
		INDEX	LOCCTR
		TS	PUSHLOC		# OFF TO PREPARE FOR INTERPRETIVE PROGRAMS.

		CCS	LOCCTR		# IF CORE SET ZERO IS BEING LOADED, SET UP
		TCF	SETLOC		# OVFIND AND FIXLOC IMMEDIATELY.
		TS	OVFIND
		CA	PUSHLOC
		TS	FIXLOC

SPECTEST	CCS	NEWJOB		# SEE IF ANY ACTIVE JOBS WAITING (RARE).
		TCF	SETLOC		# MUST BE AWAKENED OUT UNCHANGED JOB.
		TC	CCSHOLE
		TC	CCSHOLE
		TS	NEWJOB		# +0 SHOWS ACTIVE JOB ALREADY SET.
		DXCH	NEWLOC
		DXCH	LOC
		TCF	ENDFIND

SETLOC		DXCH	NEWLOC		# SET UP THE LOCATION REGISTERS FOR THIS
		INDEX	LOCCTR
		DXCH	LOC
		INDEX	NEWJOB		# THIS INDEX INSTRUCTION INSURES THAT THE
		CS	PRIORITY	# HIGHEST ACTIVE PRIORITY WILL BE COMPARED
		AD	NEWPRIO		# WITH THE NEW PRIORITY TO SEE IF NEWJOB
		EXTEND			# SHOULD BE SET TO SIGNAL A SWITCH.
		BZMF	ENDFIND
		CA	LOCCTR		# LOCCTR IS LEFT SET AT THIS CORE SET IF
		TS	NEWJOB		# THE CALLER WANTS TO LOAD ANY MPAC
		TCF	ENDFIND		# REGISTERS, ETC.

NEXTCORE	CAF	COREINC
		ADS	LOCCTR
		CCS	EXECTEM2
		TCF	NOVAC3
		TC	BAILOUT		# NO CORE SETS.
		OCT	1202
# Page 1213
# THE FOLLOWING ROUTINE SWAPS CORE SET 0 WITH THAT WHOSE RELATIVE ADDRESS IS IN NEWJOB.

	-2	LXCH	LOC
	-1	CAE	BANKSET		# BANKSET, NOT BBANK, HAS RIGHT CONTENTS.
CHANJOB		INHINT
		EXTEND
		ROR	SUPERBNK	# PICK UP CURRENT SBANK FOR BBCON
		XCH	L		# LOC IN A AND BBCON IN L.
	+4	INDEX	NEWJOB		# SWAP LOC AND BANKSET.
		DXCH	LOC
		DXCH	LOC

		CAE	BANKSET
		EXTEND
		WRITE	SUPERBNK	# SET SBANK FOR NEW JOB.
		DXCH	MPAC		# SWAP MULTI-PURPOSE ACCUMULATOR AREAS.
		INDEX	NEWJOB
		DXCH	MPAC
		DXCH	MPAC
		DXCH	MPAC +2
		INDEX	NEWJOB
		DXCH	MPAC +2
		DXCH	MPAC +2
		DXCH	MPAC +4
		INDEX	NEWJOB
		DXCH	MPAC +4
		DXCH	MPAC +4
		DXCH	MPAC +6
		INDEX	NEWJOB
		DXCH	MPAC +6
		DXCH	MPAC +6

		CAF	ZERO
		XCH	OVFIND		# MAKE PUSHLOC NEGATIVE IF OVFIND NZ.
		EXTEND
		BZF	+3
		CS	PUSHLOC
		TS	PUSHLOC

		DXCH	PUSHLOC
		INDEX	NEWJOB
		DXCH	PUSHLOC
		DXCH	PUSHLOC		# SWAPS PUSHLOC AND PRIORITY.
		CAF	LOW9		# SET FIXLOC TO BASE OF VAC AREA.
		MASK	PRIORITY
		TS	FIXLOC

		CCS	PUSHLOC		# SET OVERFLOW INDICATOR ACCORDING TO
		CAF	ZERO
		TCF	ENDPRCHG -1

# Page 1214
		CS	PUSHLOC
		TS	PUSHLOC
		CAF	ONE
		XCH	OVFIND
		TS	NEWJOB

ENDPRCHG	RELINT
		DXCH	LOC		# BASIC JOBS HAVE POSITIVE ADDRESSES, SO
		EXTEND			# DISPATCH WITH A DTCB.
		BZMF	+2		# IF INTERPRETIVE, SET UP EBANK, ETC.
		DTCB
# Page 1215
		COM			# EPILOGUE TO JOB CHANGE FOR INTERPRETIVE
		AD	ONE
		TS	LOC		# RESUME
		TCF	INTRSM

# COMPLETE JOBSLEEP PREPARATIONS.

JOBSLP1		INHINT
		CS	PRIORITY	# NNZ PRIORITY SHOWS JOB ASLEEP.
		TS	PRIORITY
		CAF	LOW7
		MASK	BBANK
		EXTEND
		ROR	SUPERBNK	# SAVE OLD SUPERBANK VALUE.
		TS	BANKSET
		CS	ZERO
JOBSLP2		TS	BUF 	+1	# HOLDS -- HIGHEST PRIORITY.
		TCF	EJSCAN		# SCAN FOR HIGHEST PRIORITY ALA ENDOFJOB.

NUCHANG2	INHINT			# QUICK... DON'T LET NEWJOB CHANGE TO +0.
		CCS	NEWJOB
		TCF		+3	# NEWJOB STILL PNZ
		RELINT			# NEW JOB HAS CHANGED TO +0.  WAKE UP JOB
		TCF	ADVAN 	+2	# VIA NUDIRECT.  (VERY RARE CASE.)

		CAF	TWO
		EXTEND
		WOR	DSALMOUT	# TURN ON ACTIVITY LIGHT
		DXCH	LOC		# AND SAVE ADDRESS INFO FOR BENEFIT OF
		TCF	CHANJOB +4	# 	POSSIBLE SLEEPING JOB.

# Page 1216
# TO WAKE UP A JOB, EACH CORE SET IS FOUND TO LOCATE ALL JOBS WHICH ARE ASLEEP.  IF THE FCADR IN THE
# LOC REGISTER OF ANY SUCH JOB MATCHES THAT SUPPLIED BY THE CALLER, THAT JOB IS AWAKENED.  IF NO JOB IS FOUND,
# LOCCTR IS SET TO -1 AND NO FURTHER ACTION TAKES PLACE.

JOBWAKE2	TS	EXECTEM1
		CAF	ZERO		# BEGIN CORE SET SCAN
		TS	LOCCTR
		CAF	NO.CORES
JOBWAKE4	TS	EXECTEM2
		INDEX	LOCCTR
		CCS	PRIORITY
		TCF	JOBWAKE3	# ACTIVE JOB -- CHECK NEXT CORE SET.
COREINC		DEC	12		# 12 REGISTERS PER CORE SET.
		TCF	WAKETEST	# SLEEPING JOB -- SEE IF CADR MATCHES.

JOBWAKE3	CAF	COREINC
		ADS	LOCCTR
		CCS	EXECTEM2
		TCF	JOBWAKE4
		CS	ONE		# EXIT IF SLEEPIG JOB NOT FOUND.
		TS	LOCCTR
		TCF	ENDFIND

WAKETEST	CS	NEWLOC
		INDEX	LOCCTR
		AD	LOC
		EXTEND
		BZF	+2		# IF MATCH.
		TCF 	JOBWAKE3	# EXAMINE NEXT CORE SET IF NO MATCH.

		INDEX	LOCCTR		# RE-COMPLEMENT PRIORITY TO SHOW JOB AWAKE
		CS	PRIORITY
		TS	NEWPRIO
		INDEX	LOCCTR
		TS	PRIORITY

		CS	FBANKMSK	# MASK UP THE 2CADR OF THE WAKE ADDRESS
		MASK	NEWLOC		# USING THE CADR IN NEWLOC AND THE EBANK
		AD	2K		# HALF OF BBANK SAVED IN BANKSET.
		XCH	NEWLOC
		MASK	FBANKMSK
		INDEX	LOCCTR
		AD	BANKSET
		TS	NEWLOC +1

		CCS	LOCCTR		# SPECIAL TREATMENT IF THIS JOB WAS
		TCF	SETLOC		# ALREADY IN THE RUN (0) POSITION.
		TCF	SPECTEST

# Page 1217
# PRIORITY CHANGE.  CHANGE THE CONTENTS OF PRIORITY AND SCAN FOR THE JOB OF HIGHEST PRIORITY.

PRIOCH2		TS	LOC
		CAF	ZERO		# SET FLAG TO TELL ENDJOB SCANNER IF THIS
		TS	BUF		# JOB IS STILL HIGHEST PRIORITY.
		CAF	LOW9
		MASK	PRIORITY
		AD	NEWPRIO
		TS	PRIORITY
		COM
		TCF	JOBSLP2		# AND TO EJSCAN.

# Page 1218
# RELEASE THIS CORE SET AND VAC AREA AND SCAN FOR THE JOB OF HIGHEST ACTIVE PRIORITY.

ENDJOB1		INHINT
		CS	ZERO
		TS	BUF +1
		XCH	PRIORITY
		MASK	LOW9
		TS	L

		CS	FAKEPRET
		AD	L

		EXTEND
		BZMF	EJSCAN		# NOVAC ENDOFJOB

		CCS	L
		INDEX	A
		TS	0

EJSCAN		CCS	PRIORITY +12D
		TC	EJ1
		TC	CCSHOLE
		TCF	+1

		CCS	PRIORITY +24D	# EXAMINE EACH PRIORITY REGISTER TO FIND
		TC	EJ1		# THE JOB OF HIGHEST ACTIVE PRIORITY.
		TC	CCSHOLE
		TCF	+1

		CCS	PRIORITY +36D
		TC	EJ1
-CCSPR		-CCS	PRIORITY
		TCF	+1

		CCS	PRIORITY +48D
		TC	EJ1
		TC	CCSHOLE
		TCF	+1

		CCS	PRIORITY +60D
		TC	EJ1
		TC	CCSHOLE
		TCF	+1

		CCS	PRIORITY +72D
		TC	EJ1
		TC	CCSHOLE
		TCF	+1

# Page 1219
# EVALUATE THE RESULTS OF THE SCAN.

		CCS	BUF 	+1	# SEE IF THERE ARE ANY ACTIVE JOBS WAITING
		TC	CCSHOLE
		TC	CCSHOLE

		TCF	+2
		TCF	DUMMYJOB
		CCS	BUF		# BUF IS ZERO IS THIS IS A PRIOCHNG AND
		TCF	+2		# CHANGED PRIORITY IS STILL HIGHEST.
		TCF	ENDPRCHG -1

		INDEX	A		# OTHERWISE, SET NEWJOB TO THE RELATIVE
		# Was CAF --- RSB 2004
		CA	0 	-1	# ADDRESS OF THE NEW JOB'S CORE SET.
		AD	-CCSPR
		TS	NEWJOB
		TCF	CHANJOB -2

EJ1		TS	BUF 	+2
		AD	BUF 	+1	# - OLD HIGH PRIORITY.
		CCS	A
		CS	BUF 	+2
		TCF	EJ2		# NEW HIGH PRIORITY.
		NOOP
		INDEX	Q
		TC	2		# PROCEED WITH SEARCH.

EJ2		TS	BUF 	+1
		EXTEND
		QXCH	BUF		# FOR LOCATING CCS PRIORITY + X INSTR.
		INDEX	BUF
		TC	2

# Page 1220
# IDLING AND COMPUTER ACTIVITY (GREEN) LIGHT MAINTENANCE. THE IDLING ROUTIEN IS NOT A JOB IN ITSELF,
# BUT RATHER A SUBROUTINE OF THE EXECUTIVE.

		EBANK=	SELFRET		# SELF-CHECK STORAGE IN EBANK.

DUMMYJOB	CS	ZERO		# SET NEWJOB TO -0 FOR IDLING.
		TS	NEWJOB
		RELINT
		CS	TWO		# TURN OFF THE ACTIVITY LIGHT.
		EXTEND
		WAND	DSALMOUT
ADVAN		CCS	NEWJOB		# IS THE NEWJOB ACTIVE?
		TCF	NUCHANG2	# YES... ONE REQUIRING A CHANGE JOB.
		CAF	TWO		# NEW JOB ALREADY IN POSITION FOR
		TCF	NUDIRECT	# EXECUTION

		CA	SELFRET
		TS	L		# PUT RETURN ADDRESS IN L.
		CAF	SELFBANK
		TCF	SUPDXCHZ +1	# AND DISPATCH JOB.

		EBANK=	SELFRET
SELFBANK	BBCON	SELFCHK

NUDIRECT	EXTEND			# TURN THE GREEN LIGHT BACK ON.
		WOR	DSALMOUT
		DXCH	LOC		# JOBS STARTED IN THIS FASHION MUST BE
		TCF	SUPDXCHZ

		BLOCK	2		# IN FIXED-FIXED SO OTHERS MAY USE.

		COUNT	02/EXEC

# SUPDXCHZ -- ROUTINE TO TRANSFER TO SUPERBANK.
# CALLING SEQUENCE:
#		TCF	SUPDXCHZ	# WITH 2CADR OF DESIRED LOCATION IN A + l.

SUPDXCHZ	XCH	L		# BASIC.
	+1	EXTEND
		WRITE	SUPERBNK
		TS	BBANK
		TC	L

NEG100		OCT	77677