diff --git a/Source/HBIOS/cfg_MASTER.asm b/Source/HBIOS/cfg_MASTER.asm
index 5e4f8708..470a523e 100644
--- a/Source/HBIOS/cfg_MASTER.asm
+++ b/Source/HBIOS/cfg_MASTER.asm
@@ -128,6 +128,8 @@ CTCOSC		.EQU	614400		; CTC CLOCK FREQUENCY
 ;
 PCFENABLE	.EQU	FALSE		; ENABLE PCF8584 I2C CONTROLLER
 PCFBASE		.EQU	$F0		; PCF8584 BASE I/O ADDRESS
+PCFCLK		.EQU	12		; PCF CLOCK BASE
+PCFTRNS		.EQU	90		; PCF TRANSFER SPEED
 ;
 EIPCENABLE	.EQU	FALSE		; EIPC: ENABLE Z80 EIPC (Z84C15) INITIALIZATION
 ;
diff --git a/Source/HBIOS/cfg_RCZ80.asm b/Source/HBIOS/cfg_RCZ80.asm
index df87d202..77c0c6c3 100644
--- a/Source/HBIOS/cfg_RCZ80.asm
+++ b/Source/HBIOS/cfg_RCZ80.asm
@@ -96,6 +96,8 @@ CTCOSC		.SET	CPUOSC		; CTC CLOCK FREQUENCY
 ;
 PCFENABLE	.SET	FALSE		; ENABLE PCF8584 I2C CONTROLLER
 PCFBASE		.SET	$F0		; PCF8584 BASE I/O ADDRESS
+PCFCLK		.SET	8		; PCF CLOCK BASE
+PCFTRNS		.SET	90		; PCF TRANSFER SPEED
 ;
 EIPCENABLE	.SET	FALSE		; EIPC: ENABLE Z80 EIPC (Z84C15) INITIALIZATION
 ;
diff --git a/Source/HBIOS/pcf.asm b/Source/HBIOS/pcf.asm
index c8c0eaa1..0d5216c8 100644
--- a/Source/HBIOS/pcf.asm
+++ b/Source/HBIOS/pcf.asm
@@ -82,10 +82,46 @@ PCF_TRNS11 	.EQU	002H	;  11 kHz */
 PCF_TRNS15 	.EQU	003H	; 1.5 kHz */
 ;
 ; BELOW VARIABLES CONTROL PCF CLOCK DIVISOR PROGRAMMING
-; HARD-CODED FOR NOW
 ;
-PCF_CLK	  	.EQU	PCF_CLK12
-PCF_TRNS	.EQU	PCF_TRNS90
+#IF (PCFCLK = 3)
+PCF_CLK .EQU PCF_CLK3
+#ELSE
+ #IF (PCFCLK = 443)
+PCF_CLK .EQU PCF_CLK443
+ #ELSE
+  #IF (PCFCLK = 6)
+PCF_CLK .EQU PCF_CLK6
+  #ELSE
+   #IF (PCFCLK = 8)
+PCF_CLK .EQU PCF_CLK8
+   #ELSE
+    #IF (PCFCLK = 12)
+PCF_CLK .EQU PCF_CLK12
+    #ELSE ***ERROR
+     .ERROR "PCFCLK UNDEFINED OR WRONG VALUE VALID VALUES ARE (3,443,6,8,12)"
+    #ENDIF
+   #ENDIF
+  #ENDIF
+ #ENDIF
+#ENDIF
+;
+#IF (PCFTRNS = 90)
+PCF_TRNS .EQU PCF_TRNS90
+#ELSE
+ #IF (PCFTRNS = 45)
+PCF_TRNS .EQU PCF_TRNS45
+ #ELSE
+  #IF (PCFTRNS = 11)
+PCF_TRNS .EQU PCF_TRNS11
+  #ELSE
+   #IF (PCFTRNS = 15)
+PCF_TRNS .EQU PCF_TRNS15
+   #ELSE ***ERROR
+    .ERROR "PCFTRNS UNDEFINED OR WRONG VALUE VALID VALUES ARE (90,45,11,15)"
+   #ENDIF
+  #ENDIF
+ #ENDIF
+#ENDIF
 ;
 ; TIMEOUT AND DELAY VALUES (ARBITRARY)
 ;