Add $^N to RUG.

$^N sets a temporary breakpoint at the next instruction and proceeds.
When the breakpoint is hit, it's removed.  The standard breakpoint
table is used.

src/rug/ar.633

@@ -971,7 +971,10 @@ PP=.-2
 	JMP PR1
 ;B HANDLER - SET AND REMOVE BREAKPOINTS
 
-O.BKPT:	MOV #-1,A
+O.BKPT:	JSR PC,BKPT
+	JMP O.DCD		;RETURN
+
+BKPT:	MOV #-1,A
 	TST D
 	BEQ O.ERR1	;FOR NOW THAT COMMAND IS MEANINGLESS
 	ASR F		;GET ONE BIT TO CARRY
@@ -992,7 +995,7 @@ O.SET1:	MOV F,-(E)		;SET BREAKPOINT
 	BEQ O.DCDB
 	MOVB #'I,O.BPM+1-O.ADR1(E)	;SET MAP TO I SPACE
 .ENDC
-O.DCDB:	JMP O.DCD		;RETURN
+O.DCDB:	RTS PC
 
 ;$$B HANDLER DELETE BKPT AT 1500 BY 1500$$B, $$B REMOVES ALL
 DELT:	CLR D
@@ -1017,6 +1020,17 @@ DELDON:	RTS PC
 DELTB:	JSR PC,DELT1
 	BR O.DCDB
 O.ERR1:	JMP O.ERR
+; SINGLE STEP USING TEMPORARY BREAKPOINT
+O.NEXT:	MOV UPC,F
+	ADD LENGTH,F		;COMPUTE ADDRESS
+	TST (F)+		; FOR NEXT INSTRUCTION
+	MOV F,NEXT
+	MOV #1,D
+	JSR PC,BKPT		;SET TEMPORARY BREAKPOINT AT F
+	CLR D
+	JMP O.PROC		;PROCEED
+
+NEXT:	0			;SAVED ADDRESS
 
 ; SEARCHES - $MSK   HAS THE MASK
 ;		$MSK+2 HAS THE FWA
@@ -1372,10 +1386,22 @@ O.B2:
 
 	MOV F,UPC	;WANT DECREMENTED PC
 	MOVB E,O.P	;ALLOW PROCEED
+	CMP F,NEXT
+	BEQ O.B6	;TEMPORARY $^N BREAKPOINT
 	DEC O.CT(E)
 	BLE O.B5
 	JMP PR0
 
+O.B6:	MOV #1,D	;REMOVE TEMPORARY BREAKPOINT
+	JSR PC,DELT1
+	JSR PC,CRLF
+	JSR 5,TYPE
+	.ASCIZ /SN;/
+	.EVEN
+	MOV NEXT,A
+	CLR NEXT
+	BR O.B3
+
 O.B5:	MOV #1,O.CT(E)	;RESET COUNT TO 1
 	MOVB E,A
 	ADD #140,A
@@ -1386,10 +1412,10 @@ O.B5:	MOV #1,O.CT(E)	;RESET COUNT TO 1
 BPTNM==.+1
 	.ASCIZ /B ;/
 	.EVEN
-	MOV #1,BYTWRD		;SET WORD MODE
 	MOVB O.P,E
 	MOV O.ADR1(E),A	;GET ADDRESS OF BREAK
-O.B3:	MOV A,CURADR
+O.B3:	MOV #1,BYTWRD		;SET WORD MODE
+	MOV A,CURADR
 	JSR PC,GETWRD
 	MOV CURADR,A	;ARG FOR SYMBOL IN A
 	JSR 5,SYMBOL	;LOOK UP SYMBOL, TYPE IT AND ANY OFFSET
@@ -4060,6 +4086,7 @@ O.LGDR:
 	O.EFF ;  E  SEARCH EFFECTIVE ADDRESS
 	O.BKPT ;  B  BREAKPOINTS
 	O.PROC ;  P  PROCEED
+	O.NEXT ;  $^N NEXT
 	SETCMD
 	SETSMD
 	SETIMD
@@ -4129,6 +4156,7 @@ ALT:	.BYTE 'G	;  G
 	.BYTE 'E	;  E
 	.BYTE 'B	;  B
 	.BYTE 'P	;  P
+	.BYTE 16	;  ^N
 	.BYTE 'C
 	.BYTE 'S
 	.BYTE 'I