diff --git a/Source/HBIOS/dsrtc.asm b/Source/HBIOS/dsrtc.asm
index c4e8608b..be29dc5e 100644
--- a/Source/HBIOS/dsrtc.asm
+++ b/Source/HBIOS/dsrtc.asm
@@ -247,9 +247,7 @@ DSRTC_DISPATCH:
 	JP	Z,DSRTC_SETALM	; SET ALARM
 	DEC	A
 	JP	Z,DSRTC_DEVICE	; REPORT RTC DEVICE INFO
-	CALL	SYSCHK
-	LD	A,ERR_NOFUNC
-	OR	A
+	SYSCHKERR(ERR_NOFUNC)
 	RET
 ;
 ; NVRAM FUNCTIONS ARE NOT AVAILABLE IN SIMULATOR
@@ -258,9 +256,7 @@ DSRTC_GETBLK:
 DSRTC_SETBLK:
 DSRTC_GETALM:
 DSRTC_SETALM:
-	CALL	SYSCHK
-	LD	A,ERR_NOTIMPL
-	OR	A
+	SYSCHKERR(ERR_NOTIMPL)
 	RET
 ;
 ; RTC GET TIME
diff --git a/Source/HBIOS/hbios.asm b/Source/HBIOS/hbios.asm
index 4bb00aa7..9fa24610 100644
--- a/Source/HBIOS/hbios.asm
+++ b/Source/HBIOS/hbios.asm
@@ -132,6 +132,11 @@ MODCNT	.SET	MODCNT + 1
 #DEFINE	LED(N)	\;
 #ENDIF
 ;
+#DEFINE SYSCHKERR(HB_ERR) \
+  #DEFCONT \	CALL	SYSCHKA
+  #DEFCONT \	LD	A,HB_ERR
+  #DEFCONT \	OR	A
+;
 ;
 ;
 #IF (INTMODE == 0)
@@ -3128,7 +3133,7 @@ HB_DISPATCH:
 	PUSH	AF
 	LD	A,(HB_STACK - HB_STKSIZ + $08)
 	CP	$FF
-	CALL	SYSCHK
+	SYSCHKERR(ERR_INTERNAL)
 	LD	A,$FF
 	LD	(HB_STACK - HB_STKSIZ + $08),A
 	POP	AF
@@ -3156,9 +3161,7 @@ HB_DISPATCH1:
 	; FALL THRU
 ;
 HB_DISPERR:
-	CALL	SYSCHK
-	LD	A,ERR_NOFUNC
-	OR	A
+	SYSCHKERR(ERR_NOFUNC)
 	RET
 ;
 ;==================================================================================================
@@ -3620,9 +3623,7 @@ RTC_DISPATCH:
 	RET
 ;
 RTC_DISPERR:
-	CALL	SYSCHK
-	LD	A,ERR_NOHW
-	OR	A
+	SYSCHKERR(ERR_NOHW)
 	RET
 ;
 ; SET RTC DISPATCH ADDRESS, USED BY RTC DRIVERS DURING INIT
@@ -3820,9 +3821,7 @@ SYS_RESET:
 	JR	Z,SYS_RESCOLD
 	CP	BF_SYSRES_USER
 	JR	Z,SYS_RESUSER
-	CALL	SYSCHK
-	LD	A,ERR_NOFUNC
-	OR	A			; SIGNAL ERROR
+	SYSCHKERR(ERR_NOFUNC)
 	RET
 ;
 ; SOFT RESET HBIOS, RELEASE HEAP MEMORY NOT USED BY HBIOS
@@ -4026,9 +4025,7 @@ SYS_ALLOC:
 ; ALL OTHER REGISTERS PRESERVED
 ;
 SYS_FREE:
-	CALL	SYSCHK			; NOT YET IMPLEMENTED
-	LD	A,ERR_NOTIMPL		; NOT YET INMPLEMENTED
-	OR	A			; SET FLAGS
+	SYSCHKERR(ERR_NOTIMPL)		; NOT YET INMPLEMENTED
 	RET
 ;
 ; GET SYSTEM INFORMATION
@@ -4068,9 +4065,7 @@ SYS_GET:
 	JP	Z,SYS_GETBNKINFO
 	CP	BF_SYSGET_CPUSPD
 	JP	Z,SYS_GETCPUSPD
-	CALL	SYSCHK
-	LD	A,ERR_NOFUNC		; SIGNAL ERROR
-	OR	A			; SET FLAGS
+	SYSCHKERR(ERR_NOFUNC)		; SIGNAL ERROR
 	RET
 ;
 ; GET TIMER
@@ -4157,7 +4152,7 @@ SYS_GETBNKINFO:
 	XOR	A
 	RET
 ;
-; GET SYSTEM CPU SPEED ORMANCE ATTRIBUTES
+; GET SYSTEM CPU SPEED PERFORMANCE ATTRIBUTES
 ;   RETURNS:
 ;     L: CLOCK MULT (0:HALF, 1:FULL, 2: DOUBLE)
 ;     D: MEMORY WAIT STATES
@@ -4362,9 +4357,7 @@ SYS_SET:
 	JR	Z,SYS_SETBOOTINFO
 	CP	BF_SYSSET_CPUSPD
 	JR	Z,SYS_SETCPUSPD
-	CALL	SYSCHK
-	LD	A,ERR_NOFUNC		; SIGNAL ERROR
-	OR	A			; SET FLAGS
+	SYSCHKERR(ERR_NOFUNC)		; SIGNAL ERROR
 	RET
 ;
 ; SET BOOT INFORMATION
@@ -4725,9 +4718,7 @@ SYS_INT:
 	JR	Z,SYS_INTGET
 	CP	BF_SYSINT_SET
 	JR	Z,SYS_INTSET
-	CALL	SYSCHK
-	LD	A,ERR_NOFUNC		; SIGNAL ERROR
-	OR	A			; SET FLAGS
+	SYSCHKERR(ERR_NOFUNC)		; SIGNAL ERROR
 	RET
 ;
 ; GET INTERRUPT SYSTEM INFORMATION
@@ -4753,9 +4744,7 @@ SYS_INTINFO:
 ;
 SYS_INTVECADR:
 #IF (INTMODE == 0)
-	CALL	SYSCHK			; INVALID FOR INT MODE 0
-	LD	A,ERR_BADCFG		; SIGNAL ERROR
-	OR	A			; SET FLAGS
+	SYSCHKERR(ERR_BADCFG)		; SIGNAL ERROR. INVALID FOR INT MODE 0
 	RET
 #ENDIF
 #IF (INTMODE == 1)
@@ -4769,9 +4758,7 @@ SYS_INTVECADR:
 	LD	A,E			; INCOMING INDEX POSITION TO A
 	CP	C			; COMPARE TO VECTOR COUNT
 	JR	C,SYS_INTGET1		; CONTINUE IF POSITION IN RANGE
-	CALL	SYSCHK			; ELSE ERROR
-	LD	A,ERR_RANGE		; SIGNAL ERROR
-	OR	A			; SET FLAGS
+	SYSCHKERR(ERR_RANGE)		; ELSE ERROR
 	RET
 SYS_INTGET1:
 	OR	A			; CLEAR CARRY
@@ -5252,15 +5239,11 @@ HB_DISPCALC:
 	RET				; JUMP TO DRIVER FUNC ADR ON TOS
 ;
 HB_FUNCERR:
-	CALL	SYSCHK
-	LD	A,ERR_NOFUNC		; SIGNAL ERROR
-	OR	A			; SET FLAGS
+	SYSCHKERR(ERR_NOFUNC)		; SIGNAL ERROR
 	RET
 ;
 HB_UNITERR:
-	CALL	SYSCHK
-	LD	A,ERR_NOUNIT		; SIGNAL ERROR
-	OR	A			; SET FLAGS
+	SYSCHKERR(ERR_NOUNIT)		; SIGNAL ERROR
 	RET
 ;
 ; ADD AN ENTRY TO THE UNIT TABLE AT ADDRESS IN HL
@@ -5347,9 +5330,7 @@ HB_ALLOC:
 HB_ALLOC1:
 	; ERROR RETURN
 	POP	DE			; RESTORE INCOMING DE
-	CALL	SYSCHK
-	LD	A,ERR_NOMEM		; SIGNAL ERROR
-	OR	A			; SET FLAGS
+	SYSCHKERR(ERR_NOMEM)		; SIGNAL ERROR
 	RET
 ;
 HB_TMPSZ	.DW	0
@@ -6337,12 +6318,12 @@ HB_RDSEC:
 ;
 ; SYSTEM CHECK: DUMP MACHINE STATE AND CONTINUE?
 ;
-SYSCHK:
+SYSCHKA:
 	; CHECK DIAG LEVEL TO SEE IF WE SHOULD DISPLAY
 	PUSH	AF			; PRESERVE INCOMING AF VALUE
 	LD	A,(CB_DIAGLVL)		; GET DIAGNOSTIC LEVEL
 	CP	DL_ERROR		; >= ERROR LEVEL
-	JR	C,SYSCHK1		; IF NOT, GO HOME
+;	JR	C,SYSCHK1		; IF NOT, GO HOME
 	POP	AF			; RESTORE INCOMING AF VALUE
 ;
 	; DISPLAY SYSCHK MESSAGE
@@ -6351,6 +6332,17 @@ SYSCHK:
 	CALL	WRITESTR		; PRINT IT
 	POP	DE			; RESTORE DE VALUE
 	CALL	XREGDMP			; DUMP REGISTERS
+
+	; DISPLAY ERROR CODE. IT IS AT RETURN ADDRESS+1 .. LD A,XX
+	EX	(SP),HL			; GET RETURN ADDRESS
+	INC	HL			; POINT TO THE ERROR CODE
+	PUSH	AF
+	LD	A,(HL)			; DISPLAY
+	CALL	PRTHEXBYTE
+	POP	AF
+	DEC	HL			; RESTORE RETURN ADDRESS
+	EX	(SP),HL
+;
 	JR	CONTINUE		; CHECK W/ USER
 ;
 SYSCHK1:
diff --git a/Source/HBIOS/md.asm b/Source/HBIOS/md.asm
index f96a782c..8277468e 100644
--- a/Source/HBIOS/md.asm
+++ b/Source/HBIOS/md.asm
@@ -157,9 +157,7 @@ MD_FNTBL:
 MD_VERIFY:
 MD_FORMAT:
 MD_DEFMED:
-	CALL	SYSCHK			; INVALID SUB-FUNCTION
-	LD	A,ERR_NOTIMPL
-	OR	A
+	SYSCHKERR(ERR_NOTIMPL)		; INVALID SUB-FUNCTION
 	RET
 ;
 ;
@@ -182,9 +180,7 @@ MD_CAP:					; ASSUMES THAT UNIT 0 IS RAM, UNIT 1 IS ROM
 	JR	Z,MD_CAP0		; UNIT 0
 	DEC	A			; TRY UNIT 1
 	JR	Z,MD_CAP1		; UNIT 1
-	CALL	SYSCHK			; INVALID UNIT
-	LD	A,ERR_NOUNIT
-	OR	A
+	SYSCHKERR(ERR_NOUNIT)		; INVALID UNIT
 	RET
 MD_CAP0:
 	LD	A,(HCB + HCB_RAMBANKS)	; POINT TO RAM BANK COUNT
diff --git a/Source/HBIOS/ppide.asm b/Source/HBIOS/ppide.asm
index 2b18f519..fd55cb1c 100644
--- a/Source/HBIOS/ppide.asm
+++ b/Source/HBIOS/ppide.asm
@@ -470,9 +470,7 @@ PPIDE_FNTBL:
 PPIDE_VERIFY:
 PPIDE_FORMAT:
 PPIDE_DEFMED:
-	CALL	SYSCHK			; NOT IMPLEMENTED
-	LD	A,ERR_NOTIMPL
-	OR	A
+	SYSCHKERR(ERR_NOTIMPL)		; NOT IMPLEMENTED
 	RET
 ;
 ;
diff --git a/Source/HBIOS/sio.asm b/Source/HBIOS/sio.asm
index f1de029c..4342d9f2 100644
--- a/Source/HBIOS/sio.asm
+++ b/Source/HBIOS/sio.asm
@@ -843,9 +843,7 @@ SIO_INITGO:
 	LD	L,SIO1_VEC		; ASSUME CHIP 1
 	DEC	A			; CHIP 1?
 	JR	Z,SIO_INITIVT		; IF SO, DO IT
-	CALL 	SYSCHK			; IMPOSSIBLE SITUATION
-	LD	A,ERR_NOUNIT
-	OR	A
+	SYSCHKERR(ERR_NOUNIT)		; IMPOSSIBLE SITUATION
 	RET
 SIO_INITIVT:
 	LD	A,L			; VALUE TO A