diff --git a/Source/HBIOS/ez80instr.inc b/Source/HBIOS/ez80instr.inc
index dbb4ed8f..4e854af9 100644
--- a/Source/HBIOS/ez80instr.inc
+++ b/Source/HBIOS/ez80instr.inc
@@ -11,6 +11,27 @@
   #DEFINE EZ80_FN 	.DB	$49, $D7	; RST.L $10
   #DEFINE EZ80_BNKSEL 	.DB	$49, $DF	; RST.L $18
 
+  #DEFINE EZ80_UTIL_INIT	LD A, 0 \ LD B, 0 \ EZ80_FN
+  #DEFINE EZ80_UTIL_EHL_TO_HL	LD A, 0 \ LD B, 1 \ EZ80_FN
+  #DEFINE EZ80_UTIL_HL_TO_EHL	LD A, 0 \ LD B, 2 \ EZ80_FN
+
+  #DEFINE EZ80_RTC_INIT 	LD A, 1 \ LD B, 0 \ EZ80_FN
+  #DEFINE EZ80_RTC_GET_TIME 	LD A, 1	\ LD B, 1 \ EZ80_FN
+  #DEFINE EZ80_RTC_SET_TIME 	LD A, 1	\ LD B, 2 \ EZ80_FN
+
+  #DEFINE EZ80_TMR_GET_TICKS	LD A, 2 \ LD B, 0 \ EZ80_FN
+  #DEFINE EZ80_TMR_GET_SECONDS	LD A, 2 \ LD B, 1 \ EZ80_FN
+  #DEFINE EZ80_TMR_SET_TICKS	LD A, 2 \ LD B, 2 \ EZ80_FN
+  #DEFINE EZ80_TMR_SET_SECONDS	LD A, 2 \ LD B, 3 \ EZ80_FN
+
+  #DEFINE EZ80_UART_IN		LD A, 3 \ LD B, 0 \ EZ80_FN
+  #DEFINE EZ80_UART_OUT		LD A, 3 \ LD B, 1 \ EZ80_FN
+  #DEFINE EZ80_UART_IN_STAT	LD A, 3 \ LD B, 2 \ EZ80_FN
+  #DEFINE EZ80_UART_OUT_STAT	LD A, 3 \ LD B, 3 \ EZ80_FN
+  #DEFINE EZ80_UART_CONFIG	LD A, 3 \ LD B, 4 \ EZ80_FN
+  #DEFINE EZ80_UART_QUERY	LD A, 3 \ LD B, 5 \ EZ80_FN
+  #DEFINE EZ80_UART_RESET	LD A, 3 \ LD B, 6 \ EZ80_FN
+
   #DEFINE RET.L		.DB	$49 \ RET
 
   #DEFINE IN0_A(p)	.DB	$ED,$38,p
diff --git a/Source/HBIOS/ez80rtc.asm b/Source/HBIOS/ez80rtc.asm
index e58bad36..78fae96f 100644
--- a/Source/HBIOS/ez80rtc.asm
+++ b/Source/HBIOS/ez80rtc.asm
@@ -20,9 +20,7 @@ EZ80RTC_INIT:
 	CALL	NEWLINE			; FORMATTING
 	PRTS("EZ80 RTC: ON-CHIP $")
 
-	LD	A, 1			; RTC FIRMWARE FUNCTION GROUP
-	LD	B, 0			; RTC INIT FUNCTION
-	EZ80_FN	
+	EZ80_RTC_INIT()
 	JR	Z, RTC_POWERED
 
 	PUSH	AF
@@ -33,9 +31,7 @@ EZ80RTC_INIT:
 RTC_POWERED:
 	; DISPLAY CURRENT TIME
 	LD	HL, EZ80RTC_BCDBUF_EXT	; POINT TO BCD BUF EXTENDED
-	LD	A, 1			; RTC FIRMWARE FUNCTION GROUP
-	LD	B, 1			; READ DATE-TIME INTO (HL)
-	EZ80_FN
+	EZ80_RTC_GET_TIME()
 
 	LD	HL, EZ80RTC_BCDBUF	; POINT TO BCD BUF
 	CALL	PRTDT			; DISPLAY THIS TIME
@@ -83,9 +79,7 @@ EZ80RTC_DISPATCH:
 EZ80RTC_GETTIM:
 	PUSH	HL
 	LD	HL, EZ80RTC_BCDBUF_EXT	; POINT TO BCD BUF EXTENDED
-	LD	A, 1			; RTC FIRMWARE FUNCTION GROUP
-	LD	B, 1			; READ DATE-TIME INTO (HL)
-	EZ80_FN
+	EZ80_RTC_GET_TIME()		; (HL) <- TIME
 
 	LD	A, BID_BIOS		; COPY FROM BIOS BANK
 	LD	(HB_SRCBNK), A		; SET IT
@@ -118,9 +112,7 @@ EZ80RTC_SETTIM:
 
 	LD	HL, EZ80RTC_BCDBUF_EXT	; POINT TO BCD BUF EXTENDED
 	LD	(HL), $20		; CENTURY NOT SUPPORT BY HBIOS
-	LD	A, 1			; RTC FIRMWARE FUNCTION GROUP
-	LD	B, 2			; WRITE DATE-TIME FROM (HL)
-	EZ80_FN
+	EZ80_RTC_SET_TIME()		; (HL) -> SYSTEM TIME
 
 	XOR	A			; SIGNAL SUCCESS
 	RET
diff --git a/Source/HBIOS/ez80uart.asm b/Source/HBIOS/ez80uart.asm
index e79fa9a3..abc7e104 100644
--- a/Source/HBIOS/ez80uart.asm
+++ b/Source/HBIOS/ez80uart.asm
@@ -58,9 +58,7 @@ EZUART_INIT:
 ;  A: Status (0-OK, else error)
 ;
 EZUART_IN:
-	LD	A, 3			; UART
-	LD	B, 0			; UART-IN
-	EZ80_FN				; CHAR RETURNED IN E
+	EZ80_UART_IN()			; CHAR RETURNED IN E
 	RET
 ;
 ; ### Function 0x01 -- Character Output (CIOOUT)
@@ -76,9 +74,7 @@ EZUART_IN:
 ;  A: Status (0-OK, else error)
 ;
 EZUART_OUT:
-	LD	A, 3			; UART
-	LD	B, 1			; UART-OUT
-	EZ80_FN
+	EZ80_UART_OUT()
 	RET
 ;
 ; ### Function 0x02 -- Character Input Status (CIOIST)
@@ -94,9 +90,7 @@ EZUART_OUT:
 ;  A: Status / Characters Pending
 ;
 EZUART_IST:
-	LD	A, 3			; UART
-	LD	B, 2			; UART-IST
-	EZ80_FN
+	EZ80_UART_IN_STAT()
 	RET
 ;
 ; ### Function 0x03 -- Character Output Status (CIOOST)
@@ -110,9 +104,7 @@ EZUART_IST:
 ;   A: Status (0 -> Full, 1 -> OK to send, < 0 -> HBIOS error code)
 ;
 EZUART_OST:
-	LD	A, 3			; UART
-	LD	B, 3			; UART-OST
-	EZ80_FN
+	EZ80_UART_OUT_STAT()
 	RET
 
 BAUD_RATE	.EQU	115200
@@ -137,10 +129,7 @@ EZUART_INITDEV:
 	CP	$FF
 	JR	NZ, NOT_RESET
 
-	; reset requested
-	LD	A, 3			; UART
-	LD	B, 6			; UART-RESET
-	EZ80_FN
+	EZ80_UART_RESET()
 	RET
 
 NOT_RESET:
@@ -152,10 +141,7 @@ NOT_RESET:
 	LD	DE, 75			; BAUD RATE DECODE CONSTANT
 	CALL	DECODE			; DE:HL := BAUD RATE
 
-	;; convert E:HL{15:0} to HL{23:0}
-	LD	A, 0
-	LD	B, 1			; UTIL - LD HL, E:HL
-	EZ80_FN
+	EZ80_UTIL_EHL_TO_HL()		; HL{23:0} <- E:HL{15:0}
 
 	POP	DE			; RESTORE REQUESTED LINE CHARACTERISTICS
 	LD	A, E
@@ -182,9 +168,7 @@ ISKIP3:
 
 	; D NOW CONTAINS THE LINE CONTROL BITS AS PER EZ80 FUNCTION
 
-	LD	A, 3			; UART
-	LD	B, 4			; UART-CONFIG
-	EZ80_FN
+	EZ80_UART_CONFIG()
 	RET
 
 #DEFINE	TRANSLATE(nnn,rrr) \
@@ -208,9 +192,7 @@ ISKIP3:
 ;  A: Status (0-OK, else error)
 ;
 EZUART_QUERY:
-	LD	A, 3			; UART
-	LD	B, 5			; UART-QUERY
-	EZ80_FN		
+	EZ80_UART_QUERY()
 					; HL{23:0} := BAUD RATE
 					; D = LINE CONTROL BITS
 	PUSH	DE			; SAVE D
diff --git a/Source/HBIOS/hbios.asm b/Source/HBIOS/hbios.asm
index 03c5edb0..359a3e83 100644
--- a/Source/HBIOS/hbios.asm
+++ b/Source/HBIOS/hbios.asm
@@ -1439,7 +1439,7 @@ BOOTWAIT:
 	XOR	A			; FUNCTION CODE TO INIT FIRMWARE
 	LD	HL, PLT_DESCR
 
-	EZ80_FN				; PROVIDE FIRMWARE DETAILS OF BUILD CONFIGURATION
+	EZ80_UTIL_INIT()			; PROVIDE FIRMWARE DETAILS OF BUILD CONFIGURATION
 	JR	PLT_DESCR_END
 
 PLT_DESCR:
@@ -5048,9 +5048,7 @@ SYS_GETFN:
 ;
 SYS_GETTIMER:
 #IF (CPUFAM == CPU_EZ80)
-	LD	A, 2
-	LD	B, 0			; GET TIMER TICK
-	EZ80_FN
+	EZ80_TMR_GET_TICKS()
 	RET
 
 #ELSE
@@ -5071,15 +5069,10 @@ SYS_GETTIMER:
 ;
 SYS_GETSECS:
 #IF (CPUFAM == CPU_EZ80)
-	LD	A, 2
-	LD	B, 1			; GET SECOND TICK
-	EZ80_FN
+	EZ80_TMR_GET_SECONDS()
 
-	LD	A, 0
-	LD	B, 2			; LD E:HL{15:0}, HL
-	EZ80_FN
+	EZ80_UTIL_HL_TO_EHL()		; E:HL{15:0} <- HL{23:0}
 	LD	D, 0
-
 	RET
 
 #ELSE
@@ -5302,14 +5295,8 @@ SYS_SETBOOTINFO:
 ;
 SYS_SETTIMER:
 #IF (CPUFAM == CPU_EZ80)
-	;; convert E:HL{15:0} to HL{23:0}
-	LD	A, 0
-	LD	B, 1			; UTIL - LD HL, E:HL
-	EZ80_FN
-
-	LD	A, 2		
-	LD	B, 2			; SET TICKS
-	EZ80_FN
+	EZ80_UTIL_EHL_TO_HL()		; HL{23:0} <- E:HL{15:0}
+	EZ80_TMR_SET_TICKS()
 	RET
 #ELSE
 	LD	BC,HB_TICKS
@@ -5326,13 +5313,9 @@ SYS_SETTIMER:
 ;
 SYS_SETSECS:
 #IF (CPUFAM == CPU_EZ80)
-	LD	A, 0
-	LD	B, 1			; UTIL - LD HL, E:HL
-	EZ80_FN
+	EZ80_UTIL_EHL_TO_HL()		; HL{23:0} <- E:HL{15:0}
 
-	LD	A, 2
-	LD	B, 3			; SET SECS
-	EZ80_FN
+	EZ80_TMR_SET_SECONDS()
 	RET
 #ELSE
 	LD	BC,HB_SECS