diff --git a/Source/HBIOS/Config/RCZ280_ext.asm b/Source/HBIOS/Config/RCZ280_ext.asm
index b28f1aec..9f3b2de2 100644
--- a/Source/HBIOS/Config/RCZ280_ext.asm
+++ b/Source/HBIOS/Config/RCZ280_ext.asm
@@ -36,6 +36,7 @@ Z280_MEMWAIT	.SET	0		; Z280: MEMORY WAIT STATES (0-3)
 Z280_IOWAIT	.SET	1		; Z280: I/O WAIT STATES TO ADD ABOVE 1 W/S BUILT-IN (0-3)
 Z280_INTWAIT	.SET	0		; Z280: INT ACK WAIT STATUS (0-3)
 ;
+Z2UENABLE	.SET	TRUE		; Z2U: ENABLE Z280 UART SERIAL DRIVER (Z2U.ASM)
 UARTENABLE	.SET	TRUE		; UART: ENABLE 8250/16550-LIKE SERIAL DRIVER (UART.ASM)
 ACIAENABLE	.SET	TRUE		; ACIA: ENABLE MOTOROLA 6850 ACIA DRIVER (ACIA.ASM)
 SIOENABLE	.SET	TRUE		; SIO: ENABLE ZILOG SIO SERIAL DRIVER (SIO.ASM)
diff --git a/Source/HBIOS/Config/RCZ280_nat.asm b/Source/HBIOS/Config/RCZ280_nat.asm
index 1459c043..a1b105d2 100644
--- a/Source/HBIOS/Config/RCZ280_nat.asm
+++ b/Source/HBIOS/Config/RCZ280_nat.asm
@@ -38,7 +38,7 @@ Z280_MEMWAIT	.SET	0		; Z280: MEMORY WAIT STATES (0-3)
 Z280_IOWAIT	.SET	1		; Z280: I/O WAIT STATES TO ADD ABOVE 1 W/S BUILT-IN (0-3)
 Z280_INTWAIT	.SET	0		; Z280: INT ACK WAIT STATUS (0-3)
 ;
-Z2UENABLE	.SET	TRUE		; Z2U: ENABLE Z280 UART SERICAL DRIVER (Z2U.ASM)
+Z2UENABLE	.SET	TRUE		; Z2U: ENABLE Z280 UART SERIAL DRIVER (Z2U.ASM)
 UARTENABLE	.SET	TRUE		; UART: ENABLE 8250/16550-LIKE SERIAL DRIVER (UART.ASM)
 ACIAENABLE	.SET	FALSE		; ACIA: ENABLE MOTOROLA 6850 ACIA DRIVER (ACIA.ASM)
 SIOENABLE	.SET	TRUE		; SIO: ENABLE ZILOG SIO SERIAL DRIVER (SIO.ASM)
diff --git a/Source/HBIOS/cfg_dyno.asm b/Source/HBIOS/cfg_dyno.asm
index fa112c85..339cfce7 100644
--- a/Source/HBIOS/cfg_dyno.asm
+++ b/Source/HBIOS/cfg_dyno.asm
@@ -85,7 +85,7 @@ ASCISWAP	.EQU	FALSE		; ASCI: SWAP CHANNELS
 ASCI0CFG	.EQU	DEFSERCFG	; ASCI 0: SERIAL LINE CONFIG
 ASCI1CFG	.EQU	DEFSERCFG	; ASCI 1: SERIAL LINE CONFIG
 ;
-Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERICAL DRIVER (Z2U.ASM)
+Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERIAL DRIVER (Z2U.ASM)
 ;
 ACIAENABLE	.EQU	FALSE		; ACIA: ENABLE MOTOROLA 6850 ACIA DRIVER (ACIA.ASM)
 ;
diff --git a/Source/HBIOS/cfg_ezz80.asm b/Source/HBIOS/cfg_ezz80.asm
index fc2e29e5..2519e683 100644
--- a/Source/HBIOS/cfg_ezz80.asm
+++ b/Source/HBIOS/cfg_ezz80.asm
@@ -99,7 +99,7 @@ UARTRC		.EQU	TRUE		; UART: AUTO-DETECT RC UART
 ;
 ASCIENABLE	.EQU	FALSE		; ASCI: ENABLE Z180 ASCI SERIAL DRIVER (ASCI.ASM)
 ;
-Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERICAL DRIVER (Z2U.ASM)
+Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERIAL DRIVER (Z2U.ASM)
 ;
 ACIAENABLE	.EQU	FALSE		; ACIA: ENABLE MOTOROLA 6850 ACIA DRIVER (ACIA.ASM)
 ;
diff --git a/Source/HBIOS/cfg_master.asm b/Source/HBIOS/cfg_master.asm
index aec799d8..b50d2843 100644
--- a/Source/HBIOS/cfg_master.asm
+++ b/Source/HBIOS/cfg_master.asm
@@ -129,7 +129,7 @@ ASCISWAP	.EQU	FALSE		; ASCI: SWAP CHANNELS
 ASCI0CFG	.EQU	DEFSERCFG	; ASCI 0: SERIAL LINE CONFIG
 ASCI1CFG	.EQU	DEFSERCFG	; ASCI 1: SERIAL LINE CONFIG
 ;
-Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERICAL DRIVER (Z2U.ASM)
+Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERIAL DRIVER (Z2U.ASM)
 Z2U0BASE	.EQU	$10		; Z2U 0: BASE I/O ADDRESS
 Z2U0CFG		.EQU	DEFSERCFG	; Z2U 0: SERIAL LINE CONFIG
 ;
diff --git a/Source/HBIOS/cfg_mk4.asm b/Source/HBIOS/cfg_mk4.asm
index 1b6796a8..6bda2c1c 100644
--- a/Source/HBIOS/cfg_mk4.asm
+++ b/Source/HBIOS/cfg_mk4.asm
@@ -100,7 +100,7 @@ ASCISWAP	.EQU	FALSE		; ASCI: SWAP CHANNELS
 ASCI0CFG	.EQU	DEFSERCFG	; ASCI 0: SERIAL LINE CONFIG
 ASCI1CFG	.EQU	DEFSERCFG	; ASCI 1: SERIAL LINE CONFIG
 ;
-Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERICAL DRIVER (Z2U.ASM)
+Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERIAL DRIVER (Z2U.ASM)
 ;
 ACIAENABLE	.EQU	FALSE		; ACIA: ENABLE MOTOROLA 6850 ACIA DRIVER (ACIA.ASM)
 ;
diff --git a/Source/HBIOS/cfg_n8.asm b/Source/HBIOS/cfg_n8.asm
index c612c8dc..d26166c4 100644
--- a/Source/HBIOS/cfg_n8.asm
+++ b/Source/HBIOS/cfg_n8.asm
@@ -103,7 +103,7 @@ ASCISWAP	.EQU	FALSE		; ASCI: SWAP CHANNELS
 ASCI0CFG	.EQU	DEFSERCFG	; ASCI 0: SERIAL LINE CONFIG
 ASCI1CFG	.EQU	DEFSERCFG	; ASCI 1: SERIAL LINE CONFIG
 ;
-Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERICAL DRIVER (Z2U.ASM)
+Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERIAL DRIVER (Z2U.ASM)
 ;
 ACIAENABLE	.EQU	FALSE		; ACIA: ENABLE MOTOROLA 6850 ACIA DRIVER (ACIA.ASM)
 ;
diff --git a/Source/HBIOS/cfg_rcz180.asm b/Source/HBIOS/cfg_rcz180.asm
index e05513a8..b4f58511 100644
--- a/Source/HBIOS/cfg_rcz180.asm
+++ b/Source/HBIOS/cfg_rcz180.asm
@@ -102,7 +102,7 @@ ASCISWAP	.EQU	FALSE		; ASCI: SWAP CHANNELS
 ASCI0CFG	.EQU	DEFSERCFG	; ASCI 0: SERIAL LINE CONFIG
 ASCI1CFG	.EQU	DEFSERCFG	; ASCI 1: SERIAL LINE CONFIG
 ;
-Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERICAL DRIVER (Z2U.ASM)
+Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERIAL DRIVER (Z2U.ASM)
 ;
 ACIAENABLE	.EQU	FALSE		; ACIA: ENABLE MOTOROLA 6850 ACIA DRIVER (ACIA.ASM)
 ;
diff --git a/Source/HBIOS/cfg_rcz280.asm b/Source/HBIOS/cfg_rcz280.asm
index 29e5b669..42b28a98 100644
--- a/Source/HBIOS/cfg_rcz280.asm
+++ b/Source/HBIOS/cfg_rcz280.asm
@@ -102,7 +102,7 @@ UARTRC		.EQU	TRUE		; UART: AUTO-DETECT RC UART
 ;
 ASCIENABLE	.EQU	FALSE		; ASCI: ENABLE Z180 ASCI SERIAL DRIVER (ASCI.ASM)
 ;
-Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERICAL DRIVER (Z2U.ASM)
+Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERIAL DRIVER (Z2U.ASM)
 Z2U0BASE	.EQU	$10		; Z2U 0: BASE I/O ADDRESS
 Z2U0CFG		.EQU	DEFSERCFG	; Z2U 0: SERIAL LINE CONFIG
 ;
diff --git a/Source/HBIOS/cfg_rcz80.asm b/Source/HBIOS/cfg_rcz80.asm
index 6430151c..af0c027d 100644
--- a/Source/HBIOS/cfg_rcz80.asm
+++ b/Source/HBIOS/cfg_rcz80.asm
@@ -98,7 +98,7 @@ UARTRC		.EQU	TRUE		; UART: AUTO-DETECT RC UART
 ;
 ASCIENABLE	.EQU	FALSE		; ASCI: ENABLE Z180 ASCI SERIAL DRIVER (ASCI.ASM)
 ;
-Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERICAL DRIVER (Z2U.ASM)
+Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERIAL DRIVER (Z2U.ASM)
 ;
 ACIAENABLE	.EQU	TRUE		; ACIA: ENABLE MOTOROLA 6850 ACIA DRIVER (ACIA.ASM)
 ACIADEBUG	.EQU	FALSE		; ACIA: ENABLE DEBUG OUTPUT
diff --git a/Source/HBIOS/cfg_sbc.asm b/Source/HBIOS/cfg_sbc.asm
index b8dc97f0..495c7286 100644
--- a/Source/HBIOS/cfg_sbc.asm
+++ b/Source/HBIOS/cfg_sbc.asm
@@ -94,7 +94,7 @@ UARTRC		.EQU	FALSE		; UART: AUTO-DETECT RC UART
 ;
 ASCIENABLE	.EQU	FALSE		; ASCI: ENABLE Z180 ASCI SERIAL DRIVER (ASCI.ASM)
 ;
-Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERICAL DRIVER (Z2U.ASM)
+Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERIAL DRIVER (Z2U.ASM)
 ;
 ACIAENABLE	.EQU	FALSE		; ACIA: ENABLE MOTOROLA 6850 ACIA DRIVER (ACIA.ASM)
 ;
diff --git a/Source/HBIOS/cfg_scz180.asm b/Source/HBIOS/cfg_scz180.asm
index af6b4b3e..f8fc2c1a 100644
--- a/Source/HBIOS/cfg_scz180.asm
+++ b/Source/HBIOS/cfg_scz180.asm
@@ -97,7 +97,7 @@ ASCISWAP	.EQU	FALSE		; ASCI: SWAP CHANNELS
 ASCI0CFG	.EQU	DEFSERCFG	; ASCI 0: SERIAL LINE CONFIG
 ASCI1CFG	.EQU	DEFSERCFG	; ASCI 1: SERIAL LINE CONFIG
 ;
-Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERICAL DRIVER (Z2U.ASM)
+Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERIAL DRIVER (Z2U.ASM)
 ;
 ACIAENABLE	.EQU	FALSE		; ACIA: ENABLE MOTOROLA 6850 ACIA DRIVER (ACIA.ASM)
 ;
diff --git a/Source/HBIOS/cfg_zeta.asm b/Source/HBIOS/cfg_zeta.asm
index 026e471e..788e4dfe 100644
--- a/Source/HBIOS/cfg_zeta.asm
+++ b/Source/HBIOS/cfg_zeta.asm
@@ -82,7 +82,7 @@ UARTRC		.EQU	FALSE		; UART: AUTO-DETECT RC UART
 ;
 ASCIENABLE	.EQU	FALSE		; ASCI: ENABLE Z180 ASCI SERIAL DRIVER (ASCI.ASM)
 ;
-Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERICAL DRIVER (Z2U.ASM)
+Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERIAL DRIVER (Z2U.ASM)
 ;
 ACIAENABLE	.EQU	FALSE		; ACIA: ENABLE MOTOROLA 6850 ACIA DRIVER (ACIA.ASM)
 ;
diff --git a/Source/HBIOS/cfg_zeta2.asm b/Source/HBIOS/cfg_zeta2.asm
index 9e7a447c..bf9ac447 100644
--- a/Source/HBIOS/cfg_zeta2.asm
+++ b/Source/HBIOS/cfg_zeta2.asm
@@ -93,7 +93,7 @@ UARTRC		.EQU	FALSE		; UART: AUTO-DETECT RC UART
 ;
 ASCIENABLE	.EQU	FALSE		; ASCI: ENABLE Z180 ASCI SERIAL DRIVER (ASCI.ASM)
 ;
-Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERICAL DRIVER (Z2U.ASM)
+Z2UENABLE	.EQU	FALSE		; Z2U: ENABLE Z280 UART SERIAL DRIVER (Z2U.ASM)
 ;
 ACIAENABLE	.EQU	FALSE		; ACIA: ENABLE MOTOROLA 6850 ACIA DRIVER (ACIA.ASM)
 ;
diff --git a/Source/HBIOS/z2u.asm b/Source/HBIOS/z2u.asm
index 4e4333cd..ef3644b9 100644
--- a/Source/HBIOS/z2u.asm
+++ b/Source/HBIOS/z2u.asm
@@ -48,16 +48,13 @@
 ; | +-------------- IE:		RECEIVER INT ENBABLE
 ; +---------------- EN:		RECEIVER ENABLE
 ;
-; THE Z280 UART USES MODE 3 INTERRUPT PROCESSING REGARDLESS OF THE INT
-; MODE SETTING.  SINCE MODE 3 REQUIRES A LARGE INTERRUPT VECTOR TABLE
-; AND THAT TABLE MUST BE ACCESSIBLE WITHOUT USING EXTERNAL BANK
-; SWITCHING, IT IS IMPRACTICAL TO SUPPORT THIS UART UNLESS NATIVE
-; Z280 MEMORY MANAGEMENT IS IN USE.
-;
-#IF (MEMMGR != MM_Z280)
-	.ECHO	"*** ERROR: Z280 UART REQUIRES NATIVE MEMORY MANAGER!!!\n"
-	!!!	; FORCE AN ASSEMBLY ERROR
-#ENDIF
+; INTERRUPT DRIVEN PROCESSING IS ONLY USED WHEN THE SYSTEM IS IN
+; INTERRUPT MODE 3.  THIS IS BECAUSE THE BUILT-IN UART *ALWAYS* USES
+; MODE 3 PROCESSING.  SINCE MODE 3 PROCESSING REQUIRES THE MODE 3
+; INTERRUPT VECTOR TABLE WHICH IS LARGE AND WON'T FIT WELL IN HIGH
+; RAM, IT IS IMPRACTICAL TO IMPLEMENT ANY INTERRUPT DRIVEN PROCESSING
+; UNLESS FULL BLOWN INTERRUPT MODE 3 W/ NATIVE MEMORY MANAGEMENT
+; IS BEING USED.
 ;
 Z2U_BUFSZ	.EQU	32		; RECEIVE RING BUFFER SIZE
 ;
@@ -97,7 +94,7 @@ Z2U_PREINIT2:
 	ADD	IY,DE			; BUMP IY TO NEXT ENTRY
 	DJNZ	Z2U_PREINIT0		; LOOP UNTIL DONE
 ;
-#IF (INTMODE > 0)
+#IF (INTMODE == 3)
 	; SETUP INT VECTORS AS APPROPRIATE
 	LD	A,(Z2U_DEV)		; GET DEVICE COUNT
 	OR	A			; SET FLAGS
@@ -158,7 +155,7 @@ Z2U_INIT1:
 ;
 ; RECEIVE INTERRUPT HANDLER
 ;
-#IF (INTMODE > 0)
+#IF (INTMODE == 3)
 ;
 ; INT ENTRY POINT
 ;
@@ -256,7 +253,7 @@ Z2U_FNTBL:
 	.ECHO	"*** INVALID Z2U FUNCTION TABLE ***\n"
 #ENDIF
 ;
-#IF (INTMODE == 0)
+#IF (INTMODE < 3)
 ;
 Z2U_IN:
 	CALL	Z2U_IST			; CHECK FOR CHAR READY
@@ -348,7 +345,7 @@ Z2U_OUT:
 ;
 ;
 ;
-#IF (INTMODE == 0)
+#IF (INTMODE < 3)
 ;
 Z2U_IST:
 ;
@@ -431,7 +428,7 @@ Z2U_INITDEVX:
 	OUT	(Z280_UARTCFG),A	; SET CONFIG REGISTER
 	LD	A,%10000000		; ENABLE, NO INTS, 1 STOP BITS
 	OUT	(Z280_UARTXCTL),A	; SET CONFIG REGISTER
-#IF (INTMODE > 0)
+#IF (INTMODE == 3)
 	LD	A,%11000000		; ENABLE W/ INTS
 #ELSE
 	LD	A,%10000000		; ENABLE, NO INTS
@@ -443,7 +440,7 @@ Z2U_INITDEVX:
 	LD	C,Z280_IOPR		; REG C POINTS TO I/O PAGE REGISTER
 	.DB	$ED,$6E			; LDCTL	(C),HL
 ;
-#IF (INTMODE > 0)
+#IF (INTMODE == 3)
 ;
 	; RESET THE RECEIVE BUFFER
 	LD	E,(IY+6)
@@ -525,7 +522,7 @@ Z2U_PRTCFG:
 ;
 Z2U_DEV	.DB	0			; DEVICE NUM USED DURING INIT
 ;
-#IF (INTMODE == 0)
+#IF (INTMODE < 3)
 ;
 Z2U0_RCVBUF	.EQU	0
 ;
diff --git a/Source/ver.inc b/Source/ver.inc
index 8f7fe9e3..1f737d7e 100644
--- a/Source/ver.inc
+++ b/Source/ver.inc
@@ -2,4 +2,4 @@
 #DEFINE	RMN	1
 #DEFINE	RUP	1
 #DEFINE	RTP	0
-#DEFINE BIOSVER	"3.1.1-pre.33"
+#DEFINE BIOSVER	"3.1.1-pre.34"
diff --git a/Source/ver.lib b/Source/ver.lib
index fffe697e..85edf7f6 100644
--- a/Source/ver.lib
+++ b/Source/ver.lib
@@ -3,5 +3,5 @@ rmn	equ	1
 rup	equ	1
 rtp	equ	0
 biosver	macro
-	db	"3.1.1-pre.33"
+	db	"3.1.1-pre.34"
 	endm