Handle Overflow in CPUSPD

Edge case where the CPU speed detection routine would overflow in a fast emulator and return a speed of 0.000 MHz.  Modified to fail back to the default CPU speed from the config file if an overflow occurs.

Source/HBIOS/hbios.asm

@@ -1908,7 +1908,7 @@ HB_CPU1:
 ; LATER.
 ;
 	CALL	HB_CPUSPD		; DYNAMIC CPU SPEED DETECTION
-	JR	NZ,HB_CPUSPD2		; SKIP AHEAD IF FAILED
+	JR	NZ,HB_CPU2		; SKIP AHEAD IF FAILED
 ;
 ; RECORD THE UPDATED CPU OSCILLATOR SPEED
 ;
@@ -1921,7 +1921,7 @@ HB_CPU1:
 ;
 	LD	(HB_CPUOSC),HL		; RECORD MEASURED SPEED
 ;
-HB_CPUSPD2:
+HB_CPU2:
 ;
 ; INIT CPUKHZ BASED ON OSCILLATOR SPEED
 ;
@@ -6299,14 +6299,15 @@ HB_CPUSPD1:
 	POP	AF
 	OUT0	(Z180_DCNTL),A
   #ENDIF
-;
-	LD	A,H
-	OR	L
-	RET	Z			; FAILURE, USE DEFAULT CPU SPEED
 ;
 	; MOVE LOOP COUNT TO HL
 	PUSH	DE
 	POP	HL
+;
+	; CHECK FOR OVERFLOW (NOT TICKING)
+	LD	A,H
+	OR	L
+	JR	Z,HB_CPUSPD2		; FAILURE, USE DEFAULT CPU SPEED
 ;
 	; TIMES 4 FOR CPU SPEED IN KHZ
 ;	RES	0,L			; GRANULARITY
@@ -6366,14 +6367,14 @@ HB_RDSEC:
 	CALL	DSRTC_END		; FINISH IT
 	LD	A,E			; VALUE TO A
 	RET
-;
-  #ELSE
-;
-	OR	$FF			; SIGNAL ERROR
-	RET				; NO RTC, ABORT
 ;
 #ENDIF
 ;
+HB_CPUSPD2:
+	; HANDLE NO RTC OR NOT TICKING
+	OR	$FF			; SIGNAL ERROR
+	RET				; AND DONE
+;
 ; SYSTEM CHECK: DUMP MACHINE STATE AND CONTINUE?
 ;
 SYSCHKA: