diff --git a/Source/HBIOS/cfg_dyno.asm b/Source/HBIOS/cfg_dyno.asm
index 8226482d..132459e3 100644
--- a/Source/HBIOS/cfg_dyno.asm
+++ b/Source/HBIOS/cfg_dyno.asm
@@ -19,6 +19,7 @@ BIOS		.EQU	BIOS_WBW	; HARDWARE BIOS: BIOS_[WBW|UNA]
 BATCOND		.EQU	FALSE		; ENABLE LOW BATTERY WARNING MESSAGE
 HBIOS_MUTEX	.EQU	FALSE		; ENABLE REENTRANT CALLS TO HBIOS (ADDS OVERHEAD)
 USELZSA2	.EQU	TRUE		; ENABLE FONT COMPRESSION
+TICKFREQ	.EQU	50		; DESIRED PERIODIC TIMER INTERRUPT FREQUENCY (HZ)
 ;
 BOOT_TIMEOUT	.EQU	0		; AUTO BOOT TIMEOUT IN SECONDS, 0 TO DISABLE
 ;
diff --git a/Source/HBIOS/cfg_ezz80.asm b/Source/HBIOS/cfg_ezz80.asm
index 990d2e1d..e5425351 100644
--- a/Source/HBIOS/cfg_ezz80.asm
+++ b/Source/HBIOS/cfg_ezz80.asm
@@ -19,6 +19,7 @@ BIOS		.EQU	BIOS_WBW	; HARDWARE BIOS: BIOS_[WBW|UNA]
 BATCOND		.EQU	FALSE		; ENABLE LOW BATTERY WARNING MESSAGE
 HBIOS_MUTEX	.EQU	FALSE		; ENABLE REENTRANT CALLS TO HBIOS (ADDS OVERHEAD)
 USELZSA2	.EQU	TRUE		; ENABLE FONT COMPRESSION
+TICKFREQ	.EQU	50		; DESIRED PERIODIC TIMER INTERRUPT FREQUENCY (HZ)
 ;
 BOOT_TIMEOUT	.EQU	0		; AUTO BOOT TIMEOUT IN SECONDS, 0 TO DISABLE
 ;
diff --git a/Source/HBIOS/cfg_master.asm b/Source/HBIOS/cfg_master.asm
index faafae4e..01b2ee73 100644
--- a/Source/HBIOS/cfg_master.asm
+++ b/Source/HBIOS/cfg_master.asm
@@ -16,6 +16,7 @@ BIOS		.EQU	BIOS_WBW	; HARDWARE BIOS: BIOS_[WBW|UNA]
 BATCOND		.EQU	FALSE		; ENABLE LOW BATTERY WARNING MESSAGE
 HBIOS_MUTEX	.EQU	FALSE		; ENABLE REENTRANT CALLS TO HBIOS (ADDS OVERHEAD)
 USELZSA2	.EQU	TRUE		; ENABLE FONT COMPRESSION
+TICKFREQ	.EQU	50		; DESIRED PERIODIC TIMER INTERRUPT FREQUENCY (HZ)
 ;
 BOOT_TIMEOUT	.EQU	0		; AUTO BOOT TIMEOUT IN SECONDS, 0 TO DISABLE
 ;
diff --git a/Source/HBIOS/cfg_mk4.asm b/Source/HBIOS/cfg_mk4.asm
index 8e23bf25..d3bc9127 100644
--- a/Source/HBIOS/cfg_mk4.asm
+++ b/Source/HBIOS/cfg_mk4.asm
@@ -19,6 +19,7 @@ BIOS		.EQU	BIOS_WBW	; HARDWARE BIOS: BIOS_[WBW|UNA]
 BATCOND		.EQU	FALSE		; ENABLE LOW BATTERY WARNING MESSAGE
 HBIOS_MUTEX	.EQU	FALSE		; ENABLE REENTRANT CALLS TO HBIOS (ADDS OVERHEAD)
 USELZSA2	.EQU	TRUE		; ENABLE FONT COMPRESSION
+TICKFREQ	.EQU	50		; DESIRED PERIODIC TIMER INTERRUPT FREQUENCY (HZ)
 ;
 BOOT_TIMEOUT	.EQU	0		; AUTO BOOT TIMEOUT IN SECONDS, 0 TO DISABLE
 ;
diff --git a/Source/HBIOS/cfg_n8.asm b/Source/HBIOS/cfg_n8.asm
index 7cb9a714..6d669358 100644
--- a/Source/HBIOS/cfg_n8.asm
+++ b/Source/HBIOS/cfg_n8.asm
@@ -19,6 +19,7 @@ BIOS		.EQU	BIOS_WBW	; HARDWARE BIOS: BIOS_[WBW|UNA]
 BATCOND		.EQU	FALSE		; ENABLE LOW BATTERY WARNING MESSAGE
 HBIOS_MUTEX	.EQU	FALSE		; ENABLE REENTRANT CALLS TO HBIOS (ADDS OVERHEAD)
 USELZSA2	.EQU	TRUE		; ENABLE FONT COMPRESSION
+TICKFREQ	.EQU	50		; DESIRED PERIODIC TIMER INTERRUPT FREQUENCY (HZ)
 ;
 BOOT_TIMEOUT	.EQU	0		; AUTO BOOT TIMEOUT IN SECONDS, 0 TO DISABLE
 ;
diff --git a/Source/HBIOS/cfg_rcz180.asm b/Source/HBIOS/cfg_rcz180.asm
index fcdf9d72..ec13c61b 100644
--- a/Source/HBIOS/cfg_rcz180.asm
+++ b/Source/HBIOS/cfg_rcz180.asm
@@ -19,6 +19,7 @@ BIOS		.EQU	BIOS_WBW	; HARDWARE BIOS: BIOS_[WBW|UNA]
 BATCOND		.EQU	FALSE		; ENABLE LOW BATTERY WARNING MESSAGE
 HBIOS_MUTEX	.EQU	FALSE		; ENABLE REENTRANT CALLS TO HBIOS (ADDS OVERHEAD)
 USELZSA2	.EQU	TRUE		; ENABLE FONT COMPRESSION
+TICKFREQ	.EQU	50		; DESIRED PERIODIC TIMER INTERRUPT FREQUENCY (HZ)
 ;
 BOOT_TIMEOUT	.EQU	0		; AUTO BOOT TIMEOUT IN SECONDS, 0 TO DISABLE
 ;
diff --git a/Source/HBIOS/cfg_rcz80.asm b/Source/HBIOS/cfg_rcz80.asm
index 02a35956..7896465a 100644
--- a/Source/HBIOS/cfg_rcz80.asm
+++ b/Source/HBIOS/cfg_rcz80.asm
@@ -19,6 +19,7 @@ BIOS		.EQU	BIOS_WBW	; HARDWARE BIOS: BIOS_[WBW|UNA]
 BATCOND		.EQU	FALSE		; ENABLE LOW BATTERY WARNING MESSAGE
 HBIOS_MUTEX	.EQU	FALSE		; ENABLE REENTRANT CALLS TO HBIOS (ADDS OVERHEAD)
 USELZSA2	.EQU	TRUE		; ENABLE FONT COMPRESSION
+TICKFREQ	.EQU	50		; DESIRED PERIODIC TIMER INTERRUPT FREQUENCY (HZ)
 ;
 BOOT_TIMEOUT	.EQU	0		; AUTO BOOT TIMEOUT IN SECONDS, 0 TO DISABLE
 ;
diff --git a/Source/HBIOS/cfg_sbc.asm b/Source/HBIOS/cfg_sbc.asm
index e682bc01..f834039d 100644
--- a/Source/HBIOS/cfg_sbc.asm
+++ b/Source/HBIOS/cfg_sbc.asm
@@ -19,6 +19,7 @@ BIOS		.EQU	BIOS_WBW	; HARDWARE BIOS: BIOS_[WBW|UNA]
 BATCOND		.EQU	FALSE		; ENABLE LOW BATTERY WARNING MESSAGE
 HBIOS_MUTEX	.EQU	FALSE		; ENABLE REENTRANT CALLS TO HBIOS (ADDS OVERHEAD)
 USELZSA2	.EQU	TRUE		; ENABLE FONT COMPRESSION
+TICKFREQ	.EQU	50		; DESIRED PERIODIC TIMER INTERRUPT FREQUENCY (HZ)
 ;
 BOOT_TIMEOUT	.EQU	0		; AUTO BOOT TIMEOUT IN SECONDS, 0 TO DISABLE
 ;
diff --git a/Source/HBIOS/cfg_scz180.asm b/Source/HBIOS/cfg_scz180.asm
index 07d679ce..3f72aefa 100644
--- a/Source/HBIOS/cfg_scz180.asm
+++ b/Source/HBIOS/cfg_scz180.asm
@@ -19,6 +19,7 @@ BIOS		.EQU	BIOS_WBW	; HARDWARE BIOS: BIOS_[WBW|UNA]
 BATCOND		.EQU	FALSE		; ENABLE LOW BATTERY WARNING MESSAGE
 HBIOS_MUTEX	.EQU	FALSE		; ENABLE REENTRANT CALLS TO HBIOS (ADDS OVERHEAD)
 USELZSA2	.EQU	TRUE		; ENABLE FONT COMPRESSION
+TICKFREQ	.EQU	50		; DESIRED PERIODIC TIMER INTERRUPT FREQUENCY (HZ)
 ;
 BOOT_TIMEOUT	.EQU	0		; AUTO BOOT TIMEOUT IN SECONDS, 0 TO DISABLE
 ;
diff --git a/Source/HBIOS/cfg_zeta.asm b/Source/HBIOS/cfg_zeta.asm
index 93dcb107..13ecfb5d 100644
--- a/Source/HBIOS/cfg_zeta.asm
+++ b/Source/HBIOS/cfg_zeta.asm
@@ -19,6 +19,7 @@ BIOS		.EQU	BIOS_WBW	; BIOS_[WBW|UNA]: HARDWARE BIOS
 BATCOND		.EQU	FALSE		; ENABLE LOW BATTERY WARNING MESSAGE
 HBIOS_MUTEX	.EQU	FALSE		; ENABLE REENTRANT CALLS TO HBIOS (ADDS OVERHEAD)
 USELZSA2	.EQU	TRUE		; ENABLE FONT COMPRESSION
+TICKFREQ	.EQU	50		; DESIRED PERIODIC TIMER INTERRUPT FREQUENCY (HZ)
 ;
 BOOT_TIMEOUT	.EQU	0		; AUTO BOOT TIMEOUT IN SECONDS, 0 TO DISABLE
 ;
diff --git a/Source/HBIOS/ctc.asm b/Source/HBIOS/ctc.asm
index 0f056946..a9d80441 100644
--- a/Source/HBIOS/ctc.asm
+++ b/Source/HBIOS/ctc.asm
@@ -21,19 +21,24 @@ CTC_PREIO	.EQU	CTCBASE + CTCPRECH
 CTC_SCLIO	.EQU	CTCBASE + CTCTIMCH
 ;
   #IF (CTCMODE == CTCMODE_CTR)
-CTC_DIV		.EQU	CTCOSC / 50
+CTC_DIV		.EQU	CTCOSC / TICKFREQ
   #ENDIF
   #IF (CTCMODE == CTCMODE_TIM16)
-CTC_DIV		.EQU	CTCOSC / 16 / 50
+CTC_DIV		.EQU	CTCOSC / 16 / TICKFREQ
   #ENDIF
   #IF (CTCMODE == CTCMODE_TIM256)
-CTC_DIV		.EQU	CTCOSC / 256 / 50
+CTC_DIV		.EQU	CTCOSC / 256 / TICKFREQ
   #ENDIF
 ;
 	.ECHO "CTC DIVISOR: "
 	.ECHO CTC_DIV
 	.ECHO "\n"
 ;
+#IF ((CTC_DIV == 0) | (CTC_DIV > $FFFF))
+	.ECHO "COMPUTED CTC DIVISOR IS UNUSABLE!\n"
+	!!!
+#ENDIF
+;
 CTC_DIVHI	.EQU	((CTC_DIV >> 8) & $FF)
 CTC_DIVLO	.EQU	(CTC_DIV & $FF)
 ;
@@ -91,7 +96,7 @@ CTC_PREINIT1:
 	OUT	(CTCBASE),A		; SETUP CTC BASE INT VECTOR
 ;
 	; IN ORDER TO DIVIDE THE CTC INPUT CLOCK DOWN TO THE
-	; DESIRED 50 HZ PERIODIC INTERRUPT, WE NEED TO CONFIGURE ONE
+	; DESIRED PERIODIC INTERRUPT, WE NEED TO CONFIGURE ONE
 	; CTC CHANNEL AS A PRESCALER AND ANOTHER AS THE ACTUAL
 	; TIMER INTERRUPT.  THE PRESCALE CHANNEL OUTPUT MUST BE WIRED
 	; TO THE TIMER CHANNEL TRIGGER INPUT VIA HARDWARE.
diff --git a/Source/HBIOS/hbios.asm b/Source/HBIOS/hbios.asm
index 3af09e56..65c4dbff 100644
--- a/Source/HBIOS/hbios.asm
+++ b/Source/HBIOS/hbios.asm
@@ -1228,6 +1228,20 @@ HB_CPU2:
 	LD	(IVT(INT_TIM0)),HL	; Z180 TIMER 0
 
 	; SETUP PERIODIC TIMER INTERRUPT ON TIMER 0
+	; *** THIS ASSUMES A TICKFREQ OF 50HZ!!! ***
+;
+#IF (TICKFREQ != 50)
+	.ECHO "TICKFREQ *MUST* BE 50 FOR Z180 TIMER\n"
+	!!!
+#ENDIF
+;
+	; Z180 PRESCALES THE COUNTER BY 20 SO,
+	; RLDR = CPU CLK / 20 / TICKFREQ
+	; IF WE ASSUME TICKFREQ = 50, WE CAN SIMPIFY TO
+	; RLDR = CPU CLK / 1000
+	; NOW IF DIVIDE BOTH SIDES BY 1000, WE CAN USE
+	; CPUKHZ VALUE AND SIMPLIFY TO
+	; RLDR = CPUKHZ
 	LD	HL,(CB_CPUKHZ)		; 50HZ = 18432000 / 20 / 50 / X, SO X = CPU KHZ
 	OUT0	(Z180_TMDR0L),L		; INITIALIZE TIMER 0 DATA REGISTER
 	OUT0	(Z180_TMDR0H),H
@@ -2453,7 +2467,7 @@ SYS_GETSECS:
 	LD	A,(HB_SECTCK)
 	HB_EI
 	NEG			; CONVERT DOWNCOUNTER TO UPCOUNTER
-	ADD	A,TICKSPERSEC
+	ADD	A,TICKFREQ
 	LD	C,A
 	XOR	A
 	RET
@@ -2799,9 +2813,9 @@ HB_TICK:
 	LD	HL,HB_TICKS		; POINT TO TICK COUNTER
 	CALL	INC32HL
 	LD	HL,HB_SECTCK		; POINT TO SECONDS TICK COUNTER
-	DEC	(HL)			; COUNTDOWN 50 TICKS
+	DEC	(HL)			; COUNTDOWN ONE SECOND OF TICKS
 	JR	NZ,HB_TICK1		; NOT DONE, SKIP AHEAD
-	LD	A,TICKSPERSEC		; 50 TICKS PER SECOND
+	LD	A,TICKFREQ		; TICKS PER SECOND
 	LD	(HL),A			; RESET COUNTDOWN REGISTER
 	CALL	VEC_SECOND		; DO SECONDS PROCESSING VIA VECTOR
 ;
@@ -4179,7 +4193,7 @@ IDLECOUNT	.DB	0
 HEAPCURB	.DW	0		; MARK HEAP ADDRESS AFTER INITIALIZATION
 ;
 HB_TICKS	.FILL	4,0		; 32 BIT TICK COUNTER
-HB_SECTCK	.DB	TICKSPERSEC	; TICK COUNTER FOR FRACTIONAL SECONDS
+HB_SECTCK	.DB	TICKFREQ	; TICK COUNTER FOR FRACTIONAL SECONDS
 HB_SECS		.FILL	4,0		; 32 BIT SECONDS COUNTER
 ;
 HB_CPUTYPE	.DB	0		; 0=Z80, 1=80180, 2=SL1960, 3=ASCI BRG
diff --git a/Source/HBIOS/std.asm b/Source/HBIOS/std.asm
index 3c2f8af0..32b1739a 100644
--- a/Source/HBIOS/std.asm
+++ b/Source/HBIOS/std.asm
@@ -345,8 +345,6 @@ CPUKHZ		.SET	CPUKHZ * 2	; ADJUST FOR DOUBLE SPEED OPERATION
 ;
 CPUMHZ		.EQU	CPUKHZ / 1000	; CPU FREQ IN MHZ
 ;
-TICKSPERSEC	.EQU	50
-;
 ; MEMORY BANK CONFIGURATION
 ;
 #IF (BIOS == BIOS_UNA)
diff --git a/Source/ver.inc b/Source/ver.inc
index f20047e5..3b64400a 100644
--- a/Source/ver.inc
+++ b/Source/ver.inc
@@ -2,4 +2,4 @@
 #DEFINE	RMN	1
 #DEFINE	RUP	0
 #DEFINE	RTP	0
-#DEFINE BIOSVER	"3.1-pre.10"
+#DEFINE BIOSVER	"3.1-pre.11"
diff --git a/Source/ver.lib b/Source/ver.lib
index 821e6368..9a135bda 100644
--- a/Source/ver.lib
+++ b/Source/ver.lib
@@ -3,5 +3,5 @@ rmn	equ	1
 rup	equ	0
 rtp	equ	0
 biosver	macro
-	db	"3.1-pre.10"
+	db	"3.1-pre.11"
 	endm