Put DSDP conditionals around use of CONO bit 0.

DSD is the deselection device.  It allows the PDP-6 and PDP-10 to
share some devices and "deselect" them when they are not in use.
CONI/O bit 0 (the sign bit) is set when a device is free to use.

This change ensures the bit 0 checks are only done when DSDP is
enabled.

src/system/itsdev.977

@@ -772,9 +772,11 @@ IFN 340P,[
 	TRNN A,77
 	JRST LPTBR2
 	CONSZ DIS,7400
-	JUMPL A,SRECYC	;SPECIAL DISPLAY CHNL
+IFN DSDP,JUMPL A,SRECYC	;SPECIAL DISPLAY CHNL
+.ELSE	JRST SRECYC
+LPTBR2:
 ]
-LPTBR2:	MOVEM B,LPTB
+	MOVEM B,LPTB
 IFN PLTP,[
 	CONSZ PLT,SDS+PDS
 	JRST PLTBRK	;PLOTTER
@@ -1942,8 +1944,11 @@ BBLK
 SUBTTL	INPUT MULTIPLEXOR
 
 IFN IMXP,[
-APOTSE:	CONI MPX,T
+APOTSE:
+IFN DSDP,[
+	CONI MPX,T
 	JUMPE T,ILUUO	;MPX NOT AVAIL
+]
 	MOVE C,B
 APOTS1:	UMOVE A,(C)
 	ANDI A,377	;GET IMPX CHNL
@@ -2087,8 +2092,11 @@ UPOT6:	HRRE C,POTVAL(A)	;GET PREV INCREMENTAL VALUE
 INARK:	SETOM POTUSR(A)	;THIS POT A LOSER, FLUSH
 	SOS POTCON
 	SOS IMPXF
+IFN DSDP,[
 	SOSGE IMXNTO
-IFDEF DSDP,DATAO DSDEVN,[MPX]
+	 DATAO DSDEVN,[MPX]
+]
+.ELSE	SOS IMXNTO
 	JRST UPOTR		;RETURN FOR MORE POTS
 
 UPOT4:	HRREI C,-6(B)		;C_DELTA-6
@@ -2432,9 +2440,12 @@ BBLK
 	MOVE A,DBLKP1
 	JRST 12,@DBLKPB
 
-SRCYRB:	CONI DIS,A
+SRCYRB:
+IFN DSDP,[
+	CONI DIS,A
 	SKIPGE A
 	CONO DIS,100	;WOULD ASSIGN IF IDLE
+]
 	MOVE A,[JSR DIGNOR]
 	JRST SRCYB1
 
@@ -2645,12 +2656,15 @@ SUBTTL	340 DISPLAY
 
 ADSDV:		;A HAS NEW 340MD
 	CONO PI,CLKOFF
+IFN DSDP,[
 	CONI DIS,T	;DIS AVAILABLE
 	JUMPN T,ADSDV1	;YES
 	CONO DIS,0
 	CONI DIS,T
 	JUMPE T,ADSDVN	;DIS NOT AVAIABLE
-ADSDV1:	CONO DIS,DISCHN
+ADSDV1:
+]
+	CONO DIS,DISCHN
 	CONSO DIS,7
 	 JRST ADSDVN	;DIS NOT RUNNING
 	SKIPL T,DISUSR
@@ -3734,8 +3748,10 @@ IFN DSDP,[
 	POPJ P,
 
 NVDGET:	CONO NVDX,@TVCONO	;TRY TO ASSIGN BAT
+IFN DSDP,[
 	CONI NVDX,TT
 	JUMPE TT,CPOPJ
+]
 	JRST POPJ1
 
 
@@ -3844,10 +3860,10 @@ NEWORK:;	SKIPGE DAEMFL
 	SETOM NVDBKR	;NO MORE CROCKS FOR VIDISECTOR TO DO
 	MOVE T,TVCONO
 	TRZ T,703000	;SAVE STATE OF VIDI SELECT
-	CONI NVDX,A
+IFN DSDP,CONI NVDX,A
 	CONO NVDX,(T)
-	SKIPN A
 IFN DSDP,[
+	SKIPN A
 	DATAO DSDEV,[DSNVID]	;RE DEASSIGN VIDI IF WAS DEASSIGNED 
 			;(CONO DID CLEAR PIA, DONE, AND SET MODE FLOPS THO)
 ]
@@ -4569,8 +4585,11 @@ TABRTC:	0	;COUNT WITHIN TABRTE
 
 SUBTTL	INPUT MULTIPLEXOR ROUTINES
 
-IMPXO:	CONI MPX,T
+IMPXO:	
+IFN DSDP,[
+	CONI MPX,T
 	JUMPE T,OPNL25
+]
 	TRNN D,2
 	JRST IMPXO2	;READ AT MN PRGM
 	SKIPGE IMPXF	;IMAGE (READ AT PI)
@@ -4602,8 +4621,11 @@ AIMXW5:	IDIVI A,3
 
 IMPXCL:	TRNE A,4	;SKIP ON WAS READING AT MP
 IMXCL1:	SOS IMPXF	;WAS READING AT PI
+IFN DSDP,[
 	SOSGE IMXNTO
-IFDEF DSDP,DATAO DSDEVN,[MPX]
+	 DATAO DSDEVN,[MPX]
+]
+.ELSE	SOS IMXNTO
 	POPJ P,
 
 IMPXRS:	SETOM MPXWF
@@ -4714,8 +4736,11 @@ UPOTRT:	MOVSI 17,IMXACS
 
 SUBTTL	OUTPUT MULTIPLEXOR ROUTINES
 
-OMPXO:	CONI OMPX,T
+OMPXO:	
+IFN DSDP,[
+	CONI OMPX,T
 	JUMPE T,OPNL25
+]
 	AOS OMXNTO
 	HLL A,C
 	JSP Q,OPSLD3
@@ -4728,8 +4753,12 @@ OMXDS:
 OMPXS:	XCTR XRW,[DATAO OMPX,(C)]	;ZAP CHNL
 	POPJ P,
 
-OMPXCL:	SOSGE OMXNTO
-IFDEF DSDP,DATAO DSDEVN,[OMPX]
+OMPXCL:
+IFN DSDP,[
+	SOSGE OMXNTO
+	 DATAO DSDEVN,[OMPX]
+]
+.ELSE	SOS OMXNTO
 	POPJ P,
 
 EBLK