diff --git a/Source/HBIOS/Config/RCZ280_ext.asm b/Source/HBIOS/Config/RCZ280_ext.asm
index 5787b247..f38142f3 100644
--- a/Source/HBIOS/Config/RCZ280_ext.asm
+++ b/Source/HBIOS/Config/RCZ280_ext.asm
@@ -22,7 +22,6 @@
 ; PLEASE REFER TO THE CUSTOM BUILD INSTRUCTIONS (README.TXT) IN THE SOURCE DIRECTORY (TWO
 ; DIRECTORIES ABOVE THIS ONE).
 ;
-#DEFINE PLATFORM_NAME "RC2014 (EXT MMU)"
 #DEFINE	BOOT_DEFAULT	"H"		; DEFAULT BOOT LOADER CMD ON <CR> OR AUTO BOOT
 ;
 #include "cfg_rcz280.asm"
diff --git a/Source/HBIOS/Config/RCZ280_nat.asm b/Source/HBIOS/Config/RCZ280_nat.asm
index 518058c5..9eec800d 100644
--- a/Source/HBIOS/Config/RCZ280_nat.asm
+++ b/Source/HBIOS/Config/RCZ280_nat.asm
@@ -22,7 +22,6 @@
 ; PLEASE REFER TO THE CUSTOM BUILD INSTRUCTIONS (README.TXT) IN THE SOURCE DIRECTORY (TWO
 ; DIRECTORIES ABOVE THIS ONE).
 ;
-#DEFINE PLATFORM_NAME "RC2014 (NATIVE MMU)"
 #DEFINE	BOOT_DEFAULT	"H"		; DEFAULT BOOT LOADER CMD ON <CR> OR AUTO BOOT
 ;
 #include "cfg_rcz280.asm"
diff --git a/Source/HBIOS/acia.asm b/Source/HBIOS/acia.asm
index 54832171..0746c9cd 100644
--- a/Source/HBIOS/acia.asm
+++ b/Source/HBIOS/acia.asm
@@ -660,7 +660,7 @@ ACIA0_RCVBUF:
 ACIA0_BUFCNT    .DB     0               ; CHARACTERS IN RING BUFFER
 ACIA0_HD        .DW     ACIA0_BUF       ; BUFFER HEAD POINTER
 ACIA0_TL        .DW     ACIA0_BUF       ; BUFFER TAIL POINTER
-ACIA0_BUF       .FILL   32,0            ; RECEIVE RING BUFFER
+ACIA0_BUF       .FILL   ACIA_BUFSZ,0    ; RECEIVE RING BUFFER
 ACIA0_BUFEND    .EQU    $               ; END OF BUFFER
 ACIA0_BUFSZ     .EQU    $ - ACIA0_BUF   ; SIZE OF RING BUFFER
 ;
@@ -670,7 +670,7 @@ ACIA1_RCVBUF:
 ACIA1_BUFCNT    .DB     0               ; CHARACTERS IN RING BUFFER
 ACIA1_HD        .DW     ACIA1_BUF       ; BUFFER HEAD POINTER
 ACIA1_TL        .DW     ACIA1_BUF       ; BUFFER TAIL POINTER
-ACIA1_BUF       .FILL   32,0            ; RECEIVE RING BUFFER
+ACIA1_BUF       .FILL   ACIA_BUFSZ,0    ; RECEIVE RING BUFFER
 ACIA1_BUFEND    .EQU    $               ; END OF BUFFER
 ACIA1_BUFSZ     .EQU    $ - ACIA1_BUF   ; SIZE OF RING BUFFER
 ;
diff --git a/Source/HBIOS/asci.asm b/Source/HBIOS/asci.asm
index 57ee1e16..dc05caba 100644
--- a/Source/HBIOS/asci.asm
+++ b/Source/HBIOS/asci.asm
@@ -778,7 +778,7 @@ ASCI0_RCVBUF:
 ASCI0_BUFCNT	.DB	0		; CHARACTERS IN RING BUFFER
 ASCI0_HD	.DW	ASCI0_BUF	; BUFFER HEAD POINTER
 ASCI0_TL	.DW	ASCI0_BUF	; BUFFER TAIL POINTER
-ASCI0_BUF	.FILL	32,0		; RECEIVE RING BUFFER
+ASCI0_BUF	.FILL	ASCI_BUFSZ,0	; RECEIVE RING BUFFER
 ASCI0_BUFEND	.EQU	$		; END OF BUFFER
 ASCI0_BUFSZ	.EQU	$ - ASCI0_BUF	; SIZE OF RING BUFFER
 ;
@@ -786,7 +786,7 @@ ASCI1_RCVBUF:
 ASCI1_BUFCNT	.DB	0		; CHARACTERS IN RING BUFFER
 ASCI1_HD	.DW	ASCI1_BUF	; BUFFER HEAD POINTER
 ASCI1_TL	.DW	ASCI1_BUF	; BUFFER TAIL POINTER
-ASCI1_BUF	.FILL	32,0		; RECEIVE RING BUFFER
+ASCI1_BUF	.FILL	ASCI_BUFSZ,0	; RECEIVE RING BUFFER
 ASCI1_BUFEND	.EQU	$		; END OF BUFFER
 ASCI1_BUFSZ	.EQU	$ - ASCI1_BUF	; SIZE OF RING BUFFER
 ;
diff --git a/Source/HBIOS/hbios.asm b/Source/HBIOS/hbios.asm
index d10cddfe..b9851839 100644
--- a/Source/HBIOS/hbios.asm
+++ b/Source/HBIOS/hbios.asm
@@ -1862,7 +1862,31 @@ HB_Z280BUS1:
 	LD	A,INTMODE
 	CALL	PRTDECB
 #ENDIF
-
+;
+	CALL	PRTSTRD
+	.TEXT	", MMU=$"
+	CALL	PRTSTRD
+#IF (MEMMGR == MM_NONE)
+	.TEXT	"NONE$"
+#ENDIF
+#IF (MEMMGR == MM_SBC)
+	.TEXT	"SBC$"
+#ENDIF
+#IF (MEMMGR == MM_Z2)
+	.TEXT	"Z2$"
+#ENDIF
+#IF (MEMMGR == MM_N8)
+	.TEXT	"N8$"
+#ENDIF
+#IF (MEMMGR == MM_Z180)
+	.TEXT	"Z180$"
+#ENDIF
+#IF (MEMMGR == MM_Z280)
+	.TEXT	"Z280$"
+#ENDIF
+#IF (MEMMGR == MM_ZRC)
+	.TEXT	"ZRC$"
+#ENDIF
 ;
 ; DISPLAY MEMORY CONFIG
 ;
@@ -1979,29 +2003,10 @@ INITSYS4:
 	
 	HB_DI				; NOT SURE THIS IS NEEDED
 
-	;; FIXUP BNKSEL TO WORK ON USER MODE PDRS
-	;XOR	A
-	;LD	(W_MMU0+1),A
-	;LD	(W_MMU1+1),A
-	
 	; FIXUP BNKSEL TO WORK ON USER MODE PDRS
 	XOR	A
 	LD	(Z280_BNKSEL2+1),A
 	
-	;CALL	NEWLINE
-	;LD	DE,$1050
-	;LD	A,4
-	;CALL	PRTHEXBUF
-
-	;; FIXUP SYSCALL TO KEEP INTERRUPTS ENABLED
-	;LD	HL,$007F
-	;LD	(Z280_IVT + $50),HL
-	
-	;CALL	NEWLINE
-	;LD	DE,$1050
-	;LD	A,4
-	;CALL	PRTHEXBUF
-
 	; MAKE USER MODE BANK CORRECT
 	LD	A,(HB_CURBNK)		; GET CURRENT BANK
 	CALL	HBX_BNKSEL
@@ -3972,6 +3977,10 @@ HB_TMPREF	.DW	0
 ;==================================================================================================
 ;
 #IF (MEMMGR == MM_Z280)
+;
+	; THE Z280 IVT MUST BE ON A 4K BOUNDARY.  IT HAS BEEN LOCATED
+	; HERE IN AN EFFORT TO MINIMIZE WASTED SPACE.  THERE SHOULD BE
+	; A LITTLE LESS THAN 4K OF CODE ABOVE.
 ;
 	.FILL	$1000 - ($ & $FFF)	; MUST BE 4K ALIGNED!
 ;
@@ -4028,7 +4037,7 @@ Z280_IVT:
 	.DW	$0000			; EPU INTERNAL OPERATION EXTENDED INSTRUCTION TRAP VECTOR
 	.DW	0, 0			; RESERVED
 	.DW	0, 0			; RESERVED
-	; PROGRAM COUNTER VALUES FOR NMI/INTA
+	; PROGRAM COUNTER VALUES FOR NMI/INTA (16)
 	.DW	HBX_IV00
 	.DW	HBX_IV01
 	.DW	HBX_IV02
@@ -4045,17 +4054,19 @@ Z280_IVT:
 	.DW	HBX_IV0D
 	.DW	HBX_IV0E
 	.DW	HBX_IV0F
-	.FILL	(128 - 16) * 2, 0
-	; PROGRAM COUNTER VALUES FOR INTB
-	.FILL	128 * 2, 0
-	; PROGRAM COUNTER VALUES FOR INTC
-	.FILL	128 * 2, 0
+	; THE REMAINDER OF THE Z280 IVT IS TRUNCATED HERE BECAUSE IT
+	; TAKES A BUNCH OF SPACE AND IS NOT USED.  WE SUPPORT ONLY
+	; 16 VECTORED INTERRUPTS AND THEY MUST BE CONNECTED TO INTA.
 ;
 #ENDIF
 ;
 ; Z280 BANK SELECTION (CALLED FROM PROXY)
 ;
-#IF (MEMMGR == MM_Z280)
+; THIS VERSION USES A MASSIVE (512 BYTE) TABLE TO OPTIMIZE THE
+; SPEED OF THE BANK SWITCH.  BY USING THE TABLE, IT IS POSSIBLE
+; EXECUTE THE CORE OF THE BANKSWITCH WITH A SINGLE OTIRW.
+;
+#IF (MEMMGR == MM_Z280) & FALSE
 ;
 ; REG A HAS BANK ID
 ;
@@ -4068,7 +4079,7 @@ Z280_BNKSEL:
 	LD	C,Z280_IOPR		; I/O PAGE REGISTER TO C
 	.DB	$ED,$6E			; LDCTL (C),HL
 ;
-	; POINT HL TO STARTING ENTRY TO PROGRAM
+	; POINT HL TO STARTING ENTRY TO PROGRAM.
 	; OPTIMIZED TO ASSUME HL IS PAGE ALIGNED!
 	LD	H,Z280_PDRTBL >> 8
 	SLA	A
@@ -4082,6 +4093,11 @@ Z280_BNKSEL1:
 ;
 Z280_BNKSEL2:
 	; POINT TO FIRST PDR TO PROGRAM ($00=USER, $10=SYSTEM)
+	; THIS CODE USES $10 (FIRST SYSTEM PDR) INITIALLY FOR
+	; SYSTEM STARTUP.  ONCE WE HAVE TRANSITIONED TO THE
+	; RAM PAGE CODE OF HBIOS, THE LINE BELOW IS MODIFIED
+	; IN MEMORY TO POINT TO THE FIRST USER PDR.  THIS IS
+	; DONE NEAR INITSYS4.
 	LD	A,$10			; FIRST SYSTEM PDR
 	OUT	(Z280_MMUPDRPTR),A	; SET THE PDR POINTER
 ;
@@ -4090,7 +4106,7 @@ Z280_BNKSEL2:
 	LD	B,8			; PROGRAM 8 PDRS
 	.DB	$ED,$93			; OTIRW
 ;	
-	; SELECT I/O PAGE FOR MMU
+	; RESTORE I/O PAGE TO $00
 	LD	L,$00			; NORMAL I/O PAGE $00
 	LD	C,Z280_IOPR		; I/O PAGE REGISTER TO C
 	.DB	$ED,$6E			; LDCTL (C),HL
@@ -4105,7 +4121,7 @@ Z280_BNKSEL2:
 #ENDIF
 ;
 #IF (($ % 2) == 1)
-	; BYTE ALIGN THE TABLE
+	; WORD ALIGN THE TABLE
 	.DB	0
 #ENDIF
 ;
@@ -4402,84 +4418,70 @@ Z280_PDRTBL:
 ;
 #ENDIF
 ;
-#IF (MEMMGR == MM_Z280) & FALSE
+; Z280 BANK SELECTION (CALLED FROM PROXY)
+;
+; THIS VERSION IS SLOWER, BUT ABOIDS THE USE OF THE 512
+; BYTE TABLE.
+;
+#IF (MEMMGR == MM_Z280)
+;
+; REG A HAS BANK ID
 ;
 Z280_BNKSEL:
-	PUSH	HL
-	PUSH	DE
 	PUSH	BC
-	LD	L,$FF			; MMU PAGE I/O REG IS $FF
-	LD	C,Z280_IOPR		; REG C POINTS TO I/O PAGE REGISTER
-	.DB	$ED,$6E			; OP CODE FOR LDCTL (C),HL
-	LD	E,0			; DE IS TEMPLATE
-	BIT	7,A
-	JR	Z,MMU_ROM		; TO ROM ROUTINE IF BIT 7 IS ZERO
-	RES	7,A
-	RR	A			; EXTRACT THE LSB
-	PUSH	AF			; SAVE THE CONDITION FLAG
-	OR	$08			; RAM BASE IS $080000
-	LD	D,A			; REG D CONTAINS THE HIGH BYTE TEMPLATE
-	POP	AF
-	JR	C,W_MMU1
-	JR	W_MMU0
-MMU_ROM:
-	OR	A			; CLEAR THE CARRY FLAG
-	RR	A			; EXTRACT THE LSB
-	LD	D,A			; REG D CONTAINS THE HIGH BYTE TEMPLATE
-	JR	C,W_MMU1
-W_MMU0:
-	LD	A,$10			; SYSTEM PAGE
-	OUT	(Z280_MMUPDRPTR),A
-	LD	C,Z280_MMUBLKMOV	; ACCESS BLOCK MOVE PORT SO POINTER WILL AUTOINCREM
-	LD	H,D			; GET TEMPLATE INTO HL
-	LD	L,$0A			; LOWEST 4K OF MEMORY
-	.DB	$ED,$BF			; OUTW (C),HL
-	LD	L,$1A			; MODIFY THE TEMPLATE FOR NEXT 4K
-	.DB	$ED,$BF			; OUTW (C),HL
-	LD	L,$2A			; MODIFY THE TEMPLATE FOR NEXT 4K
-	.DB	$ED,$BF			; OUTW (C),HL
-	LD	L,$3A			; MODIFY THE TEMPLATE FOR NEXT 4K
-	.DB	$ED,$BF			; OUTW (C),HL
-	LD	L,$4A			; MODIFY THE TEMPLATE FOR NEXT 4K
-	.DB	$ED,$BF			; OUTW (C),HL
-	LD	L,$5A			; MODIFY THE TEMPLATE FOR NEXT 4K
-	.DB	$ED,$BF			; OUTW (C),HL
-	LD	L,$6A			; MODIFY THE TEMPLATE FOR NEXT 4K
-	.DB	$ED,$BF			; OUTW (C),HL  
-	LD	L,$7A			; MODIFY THE TEMPLATE FOR NEXT 4K
-	.DB	$ED,$BF			; OUTW (C),HL  
-	JR	W_MMU2
-W_MMU1:
-	LD	A,$10			; SYSTEM PAGE
-	OUT	(Z280_MMUPDRPTR),A
-	LD	C,Z280_MMUBLKMOV	; ACCESS BLOCK MOVE PORT SO POINTER WILL AUTOINCREM
-	LD	H,D			; GET TEMPLATE INTO HL
-	LD	L,$8A			; LOWEST 4K OF MEMORY
+	PUSH	HL
+;
+	; SELECT I/O PAGE FOR MMU
+	LD	L,$FF			; MMU AT I/O PAGE $FF
+	LD	C,Z280_IOPR		; I/O PAGE REGISTER TO C
+	.DB	$ED,$6E			; LDCTL (C),HL
+;
+	; CONVERT BANK ID TO TOP 12 BITS OF PHYSICAL ADDRESS
+	; WITH $0A IN THE LOW ORDER NIBBLE:
+	; BANK ID: R000 BBBB
+	; PDR: 0000 RBBB B000 1010
+;	
+	; IF R BIT (RAM/ROM) IS SET, WE WANT TO CONVERT
+	; FROM R000 BBBB -> 000R BBBB
+	BIT	7,A			; CHECK BIT
+	JR	Z,Z280_BNKSEL1		; NOT SET, SKIP AHEAD
+	XOR	%10010000		; FIX IT
+;
+Z280_BNKSEL1:
+	;MULTU	A,$80			; HL=0000 RBBB B000 0000
+	.DB	$FD,$ED,$F9,$80		; MULTU A,$80
+;	
+	LD	A,$0A			; VALUE FOR LOW NIBBLE
+	OR	L			; COMBINE WITH L
+	LD	L,A			; PUT IT BACK
+;	
+Z280_BNKSEL2:
+	; POINT TO FIRST PDR TO PROGRAM ($00=USER, $10=SYSTEM)
+	; THIS CODE USES $10 (FIRST SYSTEM PDR) INITIALLY FOR
+	; SYSTEM STARTUP.  ONCE WE HAVE TRANSITIONED TO THE
+	; RAM PAGE CODE OF HBIOS, THE LINE BELOW IS MODIFIED
+	; IN MEMORY TO POINT TO THE FIRST USER PDR.  THIS IS
+	; DONE NEAR INITSYS4.
+	LD	A,$10			; FIRST SYSTEM PDR
+	OUT	(Z280_MMUPDRPTR),A	; SET THE PDR POINTER
+;
+	; PROGRAM 8 PDRS
+	LD	C,Z280_MMUBLKMOV	; PDR BLOCK MOVE PORT
+	LD	B,8			; PROGRAM 8 PDRS
+	LD	A,$10			; PDR VALUE INCREMENT
+Z280_BNKSEL3:
 	.DB	$ED,$BF			; OUTW (C),HL
-	LD	L,$9A			; MODIFY THE TEMPLATE FOR NEXT 4K
-	.DB	$ED,$BF			; OUTW (C),HL        
-	LD	L,$AA			; MODIFY THE TEMPLATE FOR NEXT 4K
-	.DB	$ED,$BF			; OUTW (C),HL  
-	LD	L,$BA			; MODIFY THE TEMPLATE FOR NEXT 4K
-	.DB	$ED,$BF			; OUTW (C),HL  
-	LD	L,$CA			; MODIFY THE TEMPLATE FOR NEXT 4K
-	.DB	$ED,$BF			; OUTW (C),HL  
-	LD	L,$DA			; MODIFY THE TEMPLATE FOR NEXT 4K
-	.DB	$ED,$BF			; OUTW (C),HL  
-	LD	L,$EA			; MODIFY THE TEMPLATE FOR NEXT 4K
-	.DB	$ED,$BF			; OUTW (C),HL  
-	LD	L,$FA			; MODIFY THE TEMPLATE FOR NEXT 4K
-	.DB	$ED,$BF			; OUTW (C),HL        
-W_MMU2:        
-	;.DB    $ED,$65			; PCACHE
-	LD	L,$00                   ; RESTORE I/O PAGE REG TO 0
-	LD	C,Z280_IOPR
+	.DB	$ED,$6D			; ADD HL, A ; BUMP VALUE
+	DJNZ	Z280_BNKSEL3		; DO ALL PDRS
+;	
+	; RESTORE I/O PAGE TO $00
+	LD	L,$00			; NORMAL I/O PAGE $00
+	LD	C,Z280_IOPR		; I/O PAGE REGISTER TO C
 	.DB	$ED,$6E			; LDCTL (C),HL
-	POP	BC
-	POP	DE
+;	
 	POP	HL
+	POP	BC
 	RET
-;
 #ENDIF
 ;
 ; Z280 BANK COPY (CALLED FROM PROXY)
@@ -4488,13 +4490,13 @@ W_MMU2:
 ;
 Z280_BNKCPY:
 	; Z280 MEMORY TO MEMORY DMA
-	; USE FLOW THROUGH MODE DMA
+	; USE FLOW THROUGH MODE
 	; SINGLE BYTE TRANSFER
 	; TRANSACTION DESCRIPTION REGISTER (TDR)
 	; %0000 0000 0000 0000
 	; - AUTO INCREMENT MEMORY
 	; - FLOWTHROUGH OPERATION
-	; - SINGLE TRANSACTION
+	; - SINGLE TRANSACTION (CAN WE USE CONTINUOUS???)
 	; - 1 BYTE XFER SIZE
 
 	PUSH	HL
diff --git a/Source/HBIOS/z2u.asm b/Source/HBIOS/z2u.asm
index 6d8199b1..46eeb5ff 100644
--- a/Source/HBIOS/z2u.asm
+++ b/Source/HBIOS/z2u.asm
@@ -56,7 +56,7 @@
 ; UNLESS FULL BLOWN INTERRUPT MODE 3 W/ NATIVE MEMORY MANAGEMENT
 ; IS BEING USED.
 ;
-Z2U_BUFSZ	.EQU	32		; RECEIVE RING BUFFER SIZE
+Z2U_BUFSZ	.EQU	128		; RECEIVE RING BUFFER SIZE
 ;
 Z2U_NONE	.EQU	0		; NOT PRESENT
 Z2U_PRESENT	.EQU	1		; PRESENT
@@ -566,7 +566,7 @@ Z2U0_RCVBUF:
 Z2U0_BUFCNT	.DB	0		; CHARACTERS IN RING BUFFER
 Z2U0_HD		.DW	Z2U0_BUF	; BUFFER HEAD POINTER
 Z2U0_TL		.DW	Z2U0_BUF	; BUFFER TAIL POINTER
-Z2U0_BUF	.FILL	32,0		; RECEIVE RING BUFFER
+Z2U0_BUF	.FILL	Z2U_BUFSZ,0	; RECEIVE RING BUFFER
 Z2U0_BUFEND	.EQU	$		; END OF BUFFER
 Z2U0_BUFSZ	.EQU	$ - Z2U0_BUF	; SIZE OF RING BUFFER
 ;
diff --git a/Source/ver.inc b/Source/ver.inc
index 289c3d7e..0a509e88 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.39"
+#DEFINE BIOSVER	"3.1.1-pre.40"
diff --git a/Source/ver.lib b/Source/ver.lib
index 37751c05..4ceb188d 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.39"
+	db	"3.1.1-pre.40"
 	endm