Overlay Freeway Crossing and exit back to SSV.

Put the game code at address 10000 to avoid clobbering SSV.
^Z exits back to timesharing.

src/imsrc/free.way

@@ -1,6 +1,8 @@
 	TITLE              FREEWAY CROSSING PROGRAM
+IFNDEF BEGIN, BEGIN=10000
 	.INSRT IMLAC;IMDEFS
-	LOC 100
+	.ADDR.=1
+	LOC BEGIN
 	JMS INPUT  ;MAIN PROGRAM
 	JMS START1 ;START UP BY INITIALIZING
 LOOP1:	JMS KEYS ;CHECK AND ACT ON KEYBOARD
@@ -24,13 +26,13 @@ LOOP2:	JMS POS ;MODIFY CAR POSITIONS
 	JMS EXEC   ;EXECUTE DISPLAY
 	JMP LOOP2  ;END OF MAIN PROGRAM,LOOP
 POS:	0   ;GET NEW CAR POSITIONS
-	LAW CARTAB ;INDEXING
+	LAC [CARTAB] ;INDEXING
 	DAC NCARTAB' ;FOR CAR TABLE
-	LAW RVEL   ;INDEXING
+	LAC [RVEL]   ;INDEXING
 	DAC NRVEL'  ;FOR RANDOM VELOCITY
-	LAW VEL    ;INDEXING
+	LAC [VEL]    ;INDEXING
 	DAC NVEL'   ;FOR VELOCITIES
-	LAW POSIT
+	LAC [POSIT]
 	DAC NPOSIT' ;FOR CURRENT POSITIONS
 	LWC 6      ;LOOP SIX TIMES
 	DAC CTR'
@@ -147,6 +149,9 @@ KEYS:	0  ;KEYBOARD READ ROUTINE
 
 	CLA
 	KRC
+	SAM [1372]	;CONTROL-Z
+	JMP .+2
+	I JMP [101]	;BACK TO SSV
 	AND [177]
 	SAM [2]     ;TRANSMIT
 	JMP K2
@@ -221,7 +226,7 @@ INPUT:	0 ;INPUT VELOCITIES, ETC.
 	ASN        ;IF MISTAKE AND SET TO 0, SET TO 1
 	COA
 	DAC SUBVEL' ;STORE VELOCITY
-	LAW TAB1
+	LAC [TAB1]
 	ADD SUBVEL'
 	DAC VADR'
 	I LAC VADR'
@@ -277,11 +282,11 @@ INCAR:	LAC [B] ;INITIALIZE OUTPUT BUFFER
 	SUB NK2'
 	JMS OUTPUT ;OUTPUT SCORMX
 	HLT        ;INPUT CAR SPEEDS
-	LAW CARTAB ;INDEXING
+	LAC [CARTAB] ;INDEXING
 	DAC NCARTAB' ;FOR CAR CALLS
-	LAW RVEL
+	LAC [RVEL]
 	DAC NRVEL'  ;FOR RANDOM VELOCITIES
-	LAW VEL
+	LAC [VEL]
 	DAC NVEL'   ;FOR VELOCITIES
 	LWC 6
 	DAC CTR'   ;LOOP SIX TIMES
@@ -347,7 +352,7 @@ SCORMD:	0 ;ROUTINE TO MODIFY SCORE
 	DAC NSCORE'
 	CLA        ;NOW PUT IN DISPLAY
 	DAC BLANK' ;BLANK INDICATOR
-	LAW NUM1
+	LAC [NUM1]
 	DAC NNUM1'
 	LAW 12
 	DAC SDIV
@@ -402,9 +407,10 @@ START1:	0 ;ALTERNATE START LOCATION
 	CLA
 	DAC OTC'
 START4:	LAC PERMSET'
+	IOF
 	ASZ
 	JMP START3
-	LAW TAB
+	LAC [TAB]
 	DAC VADR'
 	LAC TAB
 	DAC DIGIT
@@ -464,9 +470,9 @@ ENDD:	0   ;DID THE SUBJECT MAKE IT?
 CRASH:	0 ;ROUTINE TO CHECK FOR CRASH
 	KSN
 	KRC        ;CLEAR KEYBOARD
-	LAW POSIT  ;INDEXING
+	LAC [POSIT]  ;INDEXING
 	DAC NPOSIT' ;FOR POSITIONS
-	LAW VEL
+	LAC [VEL]
 	DAC NVEL'
 	LWC 6
 	DAC CTR'   ;LOOP COUNTER
@@ -517,6 +523,9 @@ CRASH1:	KSN ;CHECK KEYBOARD
 	JMP CRASH1
 	CLA
 	KRC
+	SAM [1372]	;CONTROL-Z
+	JMP .+2
+	I JMP [101]	;BACK TO SSV
 	AND [177]
 	SAM [2]     ;CHECK FOR XMIT
 	JMP CRASH1 ;IF NOT LOOP
@@ -814,7 +823,7 @@ EXEC:	0  ;EXECUTE ONE DISPLAY CYCLE
 	LDA        ;LOAD DATA SWITCHES
 	ASM        ;SKIP IF BIT 0 ON
 	HLT        ;OTHERWISE STOP
-	LAW DIS    ;GET DISPLAY ADDRESS
+	LAC [DIS]  ;GET DISPLAY ADDRESS
 	DLA
 	DON        ;RUN DISPLAY
 	I JMP EXEC ;RETURN
@@ -1151,6 +1160,7 @@ REST:	DNOP  ;DISPLAY WAIT ROUTINE
 	DNOP
 	DRJM      ;RETURN
 DIS:	DHVC  ;START OF DISPLAY
+	DADR
 	DSTS 1
 	DLXA 1400 ;DRAW HIGHWAY
 	DLYA 4600
@@ -1490,7 +1500,7 @@ CRUNC0:	DNOP
 	DLYA 4000
 	DHLT
 L:	..ZZ=.      ;LITERALS GO HERE
-	LOC 3000
+	LOC <BEGIN+3000>&77000
 	ISZ OTA'    ;MODULE TO PRINT OUTPUT BUFFER--START HERE
 	LAC [B]
 	DAC OTB'    ;UNPACK COUNTER
@@ -1519,4 +1529,4 @@ B:	0           ;PRINT BUFFER
 	LOC ..ZZ
 	CONSTANTS   ;LITERALS
 	VARIABLES
-	END
+	END BEGIN+1