diff --git a/Source/BPBIOS/Build.cmd b/Source/BPBIOS/Build.cmd
index 7b4f4607..7f06ca88 100644
--- a/Source/BPBIOS/Build.cmd
+++ b/Source/BPBIOS/Build.cmd
@@ -10,7 +10,7 @@ set ZXINCDIR=../../tools/cpm/include/
 
 pushd ZCPR33 && call Build.cmd && popd
 
-pause
+rem pause
 
 call :makebp 33t
 call :makebp 33tbnk
@@ -25,7 +25,7 @@ call :makebp 34nbnk
 call :makebp 41tbnk
 call :makebp 41nbnk
 
-pause
+rem pause
 
 cpmrm.exe -f wbw_hd0 ../../Binary/hd0.img 0:ws*.*
 
diff --git a/Source/BPBIOS/hbios.z80 b/Source/BPBIOS/hbios.z80
index cfe8dadc..be63e92d 100644
--- a/Source/BPBIOS/hbios.z80
+++ b/Source/BPBIOS/hbios.z80
@@ -8,7 +8,8 @@ HB_DEFBNK	EQU	BID_USR		; Default bank number
 ;
 ; LOCATION OF DISPATCH ENTRY IN HBIOS BANK
 ;
-HB_DISPATCH	EQU	0403H
+HB_DISPATCH	EQU	403H
+HB_STACK	EQU	500H
 ;
 ; PLATFORM SPECIFIC CONSTANTS
 ;
@@ -76,7 +77,7 @@ HBX_BNKCPY	EQU	0FFF6H
 HBX_BNKCALL	EQU	0FFF9H
 
 HB_CURBNK	EQU	0FFE0H
-;HB_PRVBNK	EQU	0FFE1H
+HB_INVBNK	EQU	0FFE1H
 HB_SRCADR	EQU	0FFE2H
 HB_SRCBNK	EQU	0FFE4H
 HB_DSTADR	EQU	0FFE5H
@@ -114,6 +115,19 @@ HBX_INIT:
 	LD	(HB_SRCBNK),A
 	LD	(HB_DSTBNK),A
 	
+	IF  BANKED
+
+	; Copy vectors from TPA page zero to SYS page zero
+	LD	BC,(TPABNK)	; C := TPABNK, B := SYSBNK
+	CALL	XMOVE		; Set source/dest banks for copy
+	LD	HL,0		; Source address is zero
+	LD	DE,0		; Destination address is zero
+	LD	BC,40H		; Copy 40H bytes
+	CALL	MOVE		; Do it
+	LD	A,(TPABNK)	; Set all Bank regs to TPA
+
+	ENDIF
+	
 	RET
 
 HBX_XCOPY:
@@ -124,16 +138,14 @@ HBX_XCOPY:
 	RET
 
 HBX_COPY:
-	LD	(HBX_STKSAV),SP	; Save current stack
-	LD	SP,HBX_STACK	; Activate our private stack
-	CALL	HBX_BNKCPY	; Do the work with private stack active
-	LD	SP,(HBX_STKSAV)	; Back to original stack
-	RET
-
-
+	JP	HBX_BNKCPY
 	
 	IF INTPXY
-;
+
+;==================================================================================================
+; SELECT MEMORY BANK FOR LOWER 32K
+;==================================================================================================
+
 HBX_BNKSEL:
 	LD	(HB_CURBNK),A
 
@@ -186,136 +198,131 @@ HBX_ROM:
 	RLCA
 	OUT0	(CPU_BBR),A
 	RET
+
 	ENDIF
+
+;==================================================================================================
+; INTERBANK MEMORY COPY
+;==================================================================================================
+
+HBX_BNKCPY:
+	HB_DI			; NOTE: ONLY REQUIRED WHEN USING IM 1
+
+	LD	(HBX_STKSAV),SP
+	LD	SP,HBX_TMPSTK
+	LD	A,(HB_CURBNK)	; GET CURRENT BANK
+	PUSH	AF		; AND SAVE TO RESTORE LATER
+	PUSH	BC		; CUR LEN -> (SP)
 ;
-; Entry point HBX_BNKCPY is for use internally and
-; assumes a valid stack already exists in upper 32K.
+HBX_BC_LOOP:
+	EX	(SP),HL		; HL := CUR LEN, (SP) := CUR SRC
+	LD	BC,HBX_BUFSIZ	; SET BC TO BOUNCE BUFFER SIZE
+	OR	A		; CLEAR CARRY FLAG
+	SBC	HL,BC		; CUR LEN := CUR LEN - BBUF SIZE
+	JR	C,HBX_BC_LAST	; END GAME, LESS THAN BBUF BYTES LEFT
+	EX	(SP),HL		; HL := CUR SRC, (SP) := REM LEN
+	CALL	HBX_BC_ITER	; DO A FULL BBUF SIZE CHUNK
+	JR	HBX_BC_LOOP	; AND REPEAT TILL DONE
 ;
-HBX_BNKCPY:
-	; Save current bank to restore at end
-	LD	A,(HB_CURBNK)
-	LD	(HBX_CPYBNK),A
-
-	; Setup for copy loop
-	LD	(HB_SRCADR),HL	; Init working source adr
-	LD	(HB_DSTADR),DE	; Init working dest adr 
-	LD	H,B		; Move bytes to copy from BC...
-	LD	L,C		;   to HL to use as byte counter
-
-HBX_COPY2:	; Copy loop
-	LD	A,L		; Low byte of count to A
-	AND	7FH		; Isolate bits relevant to 128 byte buf
-	LD	BC,80H		; Assume full buf copy
-	JR	Z,HBX_COPY3	; If full buf copy, go do it
-	LD	C,A		; Otherwise, BC := bytes to copy
-
-HBX_COPY3:
-	PUSH	HL		; Save bytes left to copy
-	CALL	HBX_COPY4	; Do it
-	POP	HL		; Recover bytes left to copy
-	XOR	A		; Clear CF
-	SBC	HL,BC		; Reflect bytes copied in HL
-	JR	NZ,HBX_COPY2	; If any left, then loop
-
-	; FIX: this should be done elsewhere!!!
-	LD	A,HB_DEFBNK	; Default bank id
-	LD	(HB_SRCBNK),A	; ... to source bank id
-	LD	(HB_DSTBNK),A	; ... and destination bank id
-
-	LD	A,0FFH		; Load original bank ($FF is replaced at entry)
-HBX_CPYBNK	EQU	$ - 1
-
-	JR	HBX_BNKSEL	; Return via bank set
-
-HBX_COPY4:
-	; Switch to source bank
-	LD	A,(HB_SRCBNK)	; Get source bank
-	CALL	HBX_BNKSEL	; Set bank without making it current
-
-	; Copy BC bytes from HL -> BUF
-	; Allow HL to increment
-	PUSH	BC		; Save copy length
-	LD	HL,(HB_SRCADR)	; Point to source adr
-	LD	DE,HBX_BUF	; Setup buffer as interim destination
-	LDIR			; Copy BC bytes: src -> buffer
-	LD	(HB_SRCADR),HL	; Update source adr
-	POP	BC		; Recover copy length
+HBX_BC_LAST:
+	; HL IS BETWEEN -(BBUF SIZE) AND -1, BC = BBUF SIZE
+	OR	A		; CLEAR CARRY
+	ADC	HL,BC		; HL := REM LEN (0 - 127)
+	EX	(SP),HL		; HL := CUR SRC, (SP) := REM LEN
+	POP	BC		; BC := REM LEN
+	CALL	NZ,HBX_BC_ITER	; DO FINAL CHUNK, BUT ONLY IF NOT ZERO BYTES
+	POP	AF		; RECOVER ORIGINAL BANK
+	CALL	HBX_BNKSEL	; SWITCH TO CURRENT BANK AND EXIT
+	LD	SP,(HBX_STKSAV)
 	
-	; Switch to dest bank
-	LD	A,(HB_DSTBNK)	; Get destination bank
-	CALL	HBX_BNKSEL	; Set bank without making it current
-
-	; Copy BC bytes from BUF -> HL
-	; Allow DE to increment
-	PUSH	BC		; Save copy length
-	LD	HL,HBX_BUF	; Use the buffer as source now
-	LD	DE,(HB_DSTADR)	; Setup final destination for copy
-	LDIR			; Copy BC bytes: buffer -> dest
-	LD	(HB_DSTADR),DE	; Update dest adr
-	POP	BC		; Recover copy length
-
-	RET			; Done
+	HB_EI			; NOTE: ONLY REQUIRED WHEN USING IM 1
+
+	RET
 ;
+HBX_BC_ITER:
+	; HL = SRC ADR, DE = DEST ADR, BC = LEN
+	PUSH	BC		; SAVE COPY LEN
+	PUSH	DE		; FINAL DEST ON STACK
+	LD	DE,HBX_BUF	; SET DEST TO BUF
+	LD	A,(HB_SRCBNK)	; GET SOURCE BANK
+	CALL	HBX_BNKSEL	; SWITCH TO SOURCE BANK
+	LDIR			; HL -> BUF (DE), BC BYTES, HL UPDATED SRC ADR
+	POP	DE		; DE := FINAL DEST
+	POP	BC		; GET LEN BACK IN BC
+	PUSH	HL		; SAVE UPDATED SRC ADR
+	LD	HL,HBX_BUF	; SET SRC ADR TO BUF
+	LD	A,(HB_DSTBNK)	; GET DEST BANK
+	CALL	HBX_BNKSEL	; SWITCH TO DEST BANK
+	LDIR			; BUF (HL) -> DE, BC BYTES, DE UPDATED DEST ADR
+	POP	HL		; RECOVER UPDATED SRC ADR
+	; HL = UPD SRC, DE = UPD DEST, BC = 0
+	RET
+
+;==================================================================================================
 ; ENTRY POINT FOR BIOS FUNCTIONS (TARGET OF RST 08)
-;
+;==================================================================================================
+
 HBX_INVOKE:
-	LD	(HBX_STKSAV),SP	; SAVE ORIGINAL STACK FRAME
+	LD	(HBX_INVSP),SP	; SAVE ORIGINAL STACK FRAME
 	LD	A,(HB_CURBNK)	; GET CURRENT BANK
 	LD	(HB_INVBNK),A	; SAVE INVOCATION BANK
 
-	;DI
-	LD	SP,HBX_STACK	; SETUP NEW STACK FRAME
+;	HB_DI
+	LD	SP,HBX_TMPSTK	; USE SMALL TEMP STACK FRAME IN HI MEM FOR BANK SWITCH
 	LD	A,BID_HB	; HBIOS BANK
 	CALL	HBX_BNKSEL	; SELECT IT
-	;EI
+	LD	SP,HB_STACK	; NOW USE FULL HBIOS STACK IN HBIOS BANK
+;	HB_EI
 
 	CALL	HB_DISPATCH	; CALL HBIOS FUNCTION DISPATCHER
 
-	;DI
+;	HB_DI
+	LD	SP,HBX_TMPSTK	; USE SMALL TEMP STACK FRAME IN HI MEM FOR BANK SWITCH
 	PUSH	AF		; SAVE AF (FUNCTION RETURN)
 	LD	A,(HB_INVBNK)	; LOAD ORIGINAL BANK
 	CALL	HBX_BNKSEL	; SELECT IT
 	POP	AF		; RESTORE AF
-	LD	SP,(HBX_STKSAV)	; RESTORE ORIGINAL STACK FRAME
-	;EI
+	LD	SP,0		; RESTORE ORIGINAL STACK FRAME
+HBX_INVSP	EQU	$ - 2
+;	HB_EI
 
 	RET			; RETURN TO CALLER
 	
 	ENDIF
 
 ;==================================================================================================
-;	Load  A,(HL)  from  Alternate  Bank  (in Reg C)
+;	LD	A,(C:HL)
 ;==================================================================================================
 
 HBX_FRGETB:
 	LD	(HBX_STKSAV),SP	; Save current stack
-	LD	SP,HBX_STACK	; Activate our private stack
+	LD	SP,HBX_TMPSTK	; Activate our private stack
 	LD	A,(HB_CURBNK)	; Get current bank
 	LD	(HBX_BNKSAV),A	; Save current bank
 	PUSH	BC
 	LD	A,C
-	;DI
+	HB_DI
 	CALL	HBX_BNKSEL
 	LD	C,(HL)
 	LD	A,(HBX_BNKSAV)
 	CALL	HBX_BNKSEL
-	;EI
+	HB_EI
 	LD	A,C
 	POP	BC
 	LD	SP,(HBX_STKSAV)	; RESTORE ORIGINAL STACK FRAME
 	RET
 
 ;==================================================================================================
-;	Load  DE,(HL)  from  Alternate  Bank
+;	LD	DE,(C:HL)
 ;==================================================================================================
 
 HBX_FRGETW:
 	LD	(HBX_STKSAV),SP	; Save current stack
-	LD	SP,HBX_STACK	; Activate our private stack
+	LD	SP,HBX_TMPSTK	; Activate our private stack
 	LD	A,(HB_CURBNK)	; Get current bank
 	LD	(HBX_BNKSAV),A	; Save current bank
 	LD	A,C
-	;DI
+	HB_DI
 	CALL	HBX_BNKSEL
 	LD	E,(HL)
 	INC	HL
@@ -323,17 +330,17 @@ HBX_FRGETW:
 	DEC	HL
 	LD	A,(HBX_BNKSAV)
 	CALL	HBX_BNKSEL
-	;EI
+	HB_EI
 	LD	SP,(HBX_STKSAV)	; RESTORE ORIGINAL STACK FRAME
 	RET
 
 ;==================================================================================================
-;	Load  (HL),A  to  Alternate  Bank  (in Reg C)
+;	LD	(C:HL),A
 ;==================================================================================================
 
 HBX_FRPUTB:	
 	LD	(HBX_STKSAV),SP	; Save current stack
-	LD	SP,HBX_STACK	; Activate our private stack
+	LD	SP,HBX_TMPSTK	; Activate our private stack
 	PUSH	AF
 	LD	A,(HB_CURBNK)	; Get current bank
 	LD	(HBX_BNKSAV),A	; Save current bank
@@ -341,27 +348,27 @@ HBX_FRPUTB:
 	PUSH	BC
 	LD	B,A
 	LD	A,C
-	;DI
+	HB_DI
 	CALL	HBX_BNKSEL
 	LD	(HL),B
 	LD	A,(HBX_BNKSAV)
 	CALL	HBX_BNKSEL
-	;EI
+	HB_EI
 	POP	BC
 	LD	SP,(HBX_STKSAV)	; RESTORE ORIGINAL STACK FRAME
 	RET
 
 ;==================================================================================================
-;	Load  (HL),DE  to  Alternate  Bank
+;	LD	(C:HL),DE
 ;==================================================================================================
 
 HBX_FRPUTW:	
 	LD	(HBX_STKSAV),SP	; Save current stack
-	LD	SP,HBX_STACK	; Activate our private stack
+	LD	SP,HBX_TMPSTK	; Activate our private stack
 	LD	A,(HB_CURBNK)	; Get current bank
 	LD	(HBX_BNKSAV),A	; Save current bank
 	LD	A,C
-	;DI
+	HB_DI
 	CALL	HBX_BNKSEL
 	LD	(HL),E
 	INC	HL
@@ -369,26 +376,25 @@ HBX_FRPUTW:
 	DEC	HL
 	LD	A,(HBX_BNKSAV)
 	CALL	HBX_BNKSEL
-	;EI
+	HB_EI
 	LD	SP,(HBX_STKSAV)	; RESTORE ORIGINAL STACK FRAME
 	RET
 
 ;==================================================================================================
-;
 ; PRIVATE DATA
-;
+;==================================================================================================
 
 	DSEG
 
 HB_DSKBUF	DEFW	0	; Address of physical disk buffer in HBIOS bank
 HBX_BNKSAV	DEFB	0	; Saved bank id during HBIOS calls
 HBX_STKSAV	DEFW	0	; Saved stack pointer during HBIOS calls
-		DEFS	64	; Private stack for HBIOS
-HBX_STACK	EQU	$	; Top of private stack
+		DEFS	32	; Private stack for HBIOS
+HBX_TMPSTK	EQU	$	; Top of private stack
 
 	IF INTPXY
 
-HBX_RETBNK	DEFB	0	; Bank to activate on return from BNKCPY
-HBX_BUF		DEFS	80H	; Interbank copy buffer
+HBX_BUFSIZ	EQU	40H
+HBX_BUF		DEFS	HBX_BUFSIZ	; Interbank copy buffer
 
 	ENDIF
diff --git a/Source/BPBIOS/ibmv-ww.z80 b/Source/BPBIOS/ibmv-ww.z80
index 72a39f3a..540cf8a8 100644
--- a/Source/BPBIOS/ibmv-ww.z80
+++ b/Source/BPBIOS/ibmv-ww.z80
@@ -30,11 +30,11 @@ BIOSTK:	DEFB	0		; NOP if not currently in bank,
 	LD	(USP-7),HL	; Save entry HL
 	POP	HL		; Retrieve caller's return address from stack
 	LD	(USP-5),HL	; ..and set in our stack for local return
-	;DI			; No interrupts while we play with the stack
+	HB_DI			; No interrupts while we play with the stack
 	LD	(USP),SP	; Save User's Stack Pointer
 	LD	SP,USP-1	; ..and point locally, saving 1 byte for Bank
 	PUSH	AF		; Save entry A and Flags
-	LD	A,(CURBNK)	; Get current bank
+	LD	A,(HB_CURBNK)	; Get current bank
 	LD	(USP-1),A	; ..and save for exitting
 	LD	A,0C9H		; Disable other calls here
 	LD	(BIOSTK),A	; ..by poking a RETurn at entry
@@ -43,7 +43,7 @@ BIOSTK:	DEFB	0		; NOP if not currently in bank,
 	PUSH	HL		; ..at USP-2 & 3
 	LD	SP,USP-7	; Point stack pointer to do local return
 	POP	HL		; .restoring entry HL
-	;EI			; ..enabling interrupts
+	HB_EI			; ..enabling interrupts
 	RET			; And return to caller
 
 ; Restore User Stack and Bank Routine
@@ -51,7 +51,6 @@ BIOSTK:	DEFB	0		; NOP if not currently in bank,
 USRSTK:	PUSH	AF
 	LD	A,(USP-1)	; Get bank control byte from entry
 	CALL	HBX_BNKSEL
-	LD	(CURBNK),A
 	XOR	A
 	LD	(BIOSTK),A	; Patch NOP back in at start of code
 	POP	AF
@@ -65,7 +64,6 @@ USRSTK:	PUSH	AF
 FRCLR:	PUSH	AF		; Save any entry in AF
 	LD	A,(USP-1)	; Get bank control byte
 	CALL	HBX_BNKSEL
-	LD	(CURBNK),A	; WW: I ADDED THIS, IS IT RIGHT???
 	XOR	A
 	LD	(BIOSTK),A	; Patch NOP to enable stack switcher
 	POP	AF
@@ -90,7 +88,7 @@ ABORT:	LD	SP,USP		; Insure stack is in Common Memory
 ; Uses : AF
 ;::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
 
-RETMEM:	LD	A,(CURBNK)
+RETMEM:	LD	A,(HB_CURBNK)
 	RET
 
 ;::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
@@ -109,7 +107,6 @@ SELMEM:	LD	(USRBNK),A	; Update user bank
 
 SELBNK:	PUSH	AF		; Save regs
 SELBN0:	CALL	HBX_BNKSEL
-	LD	(CURBNK),A	; Save as current bank #
 	POP	AF		; restore regs
 	RET
 
@@ -188,7 +185,6 @@ FRPUTW:
 
 JPBNK:	DEFS	1		; Bank # for Far Jump or Call
 USRBNK:	DEFS	1		; User's selected bank #
-CURBNK:	DEFS	1		; Current bank #
 DMABNK:	DEFS	1		; Target bank # for disk xfers
 	DEFS	64		; 32 level stack
 USP:	DEFS	2		; User stack pointer
diff --git a/Source/BPBIOS/romwbw.lib b/Source/BPBIOS/romwbw.lib
index c6d9f83c..d666295f 100644
--- a/Source/BPBIOS/romwbw.lib
+++ b/Source/BPBIOS/romwbw.lib
@@ -66,3 +66,17 @@ MEMTOP	EQU	0FFE0H - 1	; Start of HBIOS 32 byte control block
 	ELSE
 MEMTOP	EQU	HBLOC - 1	; Start of HBIOS 512 byte proxy
 	ENDIF
+
+	IF INTPXY
+HB_EI	MACRO
+	ENDM
+HB_DI	MACRO
+	ENDM
+	ELSE
+HB_EI	MACRO
+	EI
+	ENDM
+HB_DI	MACRO
+	DI
+	ENDM
+	ENDIF
diff --git a/Source/HBIOS/hbios.asm b/Source/HBIOS/hbios.asm
index 14245931..c112c4f0 100644
--- a/Source/HBIOS/hbios.asm
+++ b/Source/HBIOS/hbios.asm
@@ -98,7 +98,7 @@ MODCNT	.SET	MODCNT + 1
 	RET
 	.FILL	(030H - $),0FFH		; RST 30
 	RET
-	.FILL	(038H - $),0FFH		; RST 38 / INT
+	.FILL	(038H - $),0FFH		; RST 38 / IM1 INT
 	RETI
 	.FILL	(066H - $),0FFH		; NMI
 	RETN
@@ -204,39 +204,42 @@ HBX_IDENT:
 ;==================================================================================================
 ;
 HBX_INVOKE:
-	LD	(HBX_STKSAV),SP	; SAVE ORIGINAL STACK FRAME
+	LD	(HBX_INVSP),SP	; SAVE ORIGINAL STACK FRAME
 	LD	A,(HB_CURBNK)	; GET CURRENT BANK
 	LD	(HB_INVBNK),A	; SAVE INVOCATION BANK
 
-	HB_DI
-	LD	SP,HBX_STACK	; USE STACK FRAME IN HI MEM
+;	HB_DI
+	LD	SP,HBX_TMPSTK	; USE SMALL TEMP STACK FRAME IN HI MEM FOR BANK SWITCH
 	LD	A,BID_BIOS	; HBIOS BANK
 	CALL	HBX_BNKSEL	; SELECT IT
 	LD	SP,HB_STACK	; NOW USE FULL HBIOS STACK IN HBIOS BANK
-	HB_EI
+;	HB_EI
 
 	CALL	HB_DISPATCH	; CALL HBIOS FUNCTION DISPATCHER
 
-	HB_DI
-	LD	SP,HBX_STACK	; USE STACK FRAME IN HI MEM
+;	HB_DI
+	LD	SP,HBX_TMPSTK	; USE SMALL TEMP STACK FRAME IN HI MEM FOR BANK SWITCH
 	PUSH	AF		; SAVE AF (FUNCTION RETURN)
 	LD	A,(HB_INVBNK)	; LOAD ORIGINAL BANK
 	CALL	HBX_BNKSEL	; SELECT IT
 	POP	AF		; RESTORE AF
 	LD	SP,0		; RESTORE ORIGINAL STACK FRAME
-HBX_STKSAV	.EQU	$ - 2
-	HB_EI
+HBX_INVSP	.EQU	$ - 2
+;	HB_EI
 
 	RET			; RETURN TO CALLER
 ;
 ;;::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
-;; SETBNK - Switch Memory Bank to Bank in A.
+;; BNKSEL - Switch Memory Bank to Bank in A.
 ;;   Preserve all Registers including Flags.
-;;   Does NOT update current bank.
-;;   Interrupts should be disabled by caller
 ;;::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
 ;
 HBX_BNKSEL:
+	; IF AN INTERRUPT OCCURS DURING THE BANK SWITCH CODE,
+	; THE BANK WILL BE SET TO (CURBNK) AS THE INTERRUPT
+	; RETURNS.  SO, IT IS IMPORTANT THAT (HB_CURBNK) BE
+	; SET AS THE FIRST STEP TO AVOID ISSUES IF AN INTERRUPT
+	; OCCURS DURING PROCESSING.
 	LD	(HB_CURBNK),A		; RECORD NEW CURRENT BANK
 ;
 HBX_BNKSEL_INT:
@@ -308,9 +311,11 @@ HBX_BNKSEL1:
 ;::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
 ;
 HBX_BNKCPY:
+#IF (INTTYPE == IT_SIMH)
 	HB_DI
+#ENDIF
 	LD	(HBX_BC_SP),SP
-	LD	SP,HBX_STACK
+	LD	SP,HBX_TMPSTK
 
 	LD	A,(HB_CURBNK)	; GET CURRENT BANK
 	PUSH	AF		; AND SAVE TO RESTORE LATER
@@ -337,7 +342,9 @@ HBX_BC_LAST:
 	CALL	HBX_BNKSEL	; SWITCH TO CURRENT BANK AND EXIT
 	LD	SP,$FFFF
 HBX_BC_SP	.EQU	$ - 2
+#IF (INTTYPE == IT_SIMH)
 	HB_EI
+#ENDIF
 	RET
 ;
 HBX_BC_ITER:
@@ -359,39 +366,39 @@ HBX_BC_ITER:
 	; HL = UPD SRC, DE = UPD DEST, BC = 0
 	RET
 ;
-; Call a routine in another bank saving and restoring the original bank.
-; Caller MUST ensure stack is already in high memory.
-; On input A=target bank, HL=target address
+; CALL A ROUTINE IN ANOTHER BANK.
+; CALLER MUST ENSURE STACK IS ALREADY IN HIGH MEMORY AND HAS ADEQUATE SPACE.
+; ON INPUT A=TARGET BANK, HL=TARGET ADDRESS
 ;
 HBX_BNKCALL:
-	HB_DI
-	LD	(HBX_TGTBNK),A	; stuff target bank to call into code below
-	LD	(HBX_TGTADR),HL	; stuff address to call into code below
-	LD	A,(HB_CURBNK)	; get current bank
-	PUSH	AF		; save for return
+	LD	(HBX_TGTBNK),A	; STUFF TARGET BANK TO CALL INTO CODE BELOW
+	LD	(HBX_TGTADR),HL	; STUFF ADDRESS TO CALL INTO CODE BELOW
+	LD	A,(HB_CURBNK)	; GET CURRENT BANK
+	PUSH	AF		; SAVE FOR RETURN
 HBX_TGTBNK	.EQU	$ + 1
-	LD	A,$FF		; load bank to call ($FF overlaid at entry)
-	CALL	HBX_BNKSEL	; activate the new bank
-	HB_EI
+	LD	A,$FF		; LOAD BANK TO CALL ($FF OVERLAID AT ENTRY)
+	CALL	HBX_BNKSEL	; ACTIVATE THE NEW BANK
 
 HBX_TGTADR	.EQU	$ + 1
-	CALL	$FFFF		; call routine ($FFFF is overlaid above)
+	CALL	$FFFF		; CALL ROUTINE ($FFFF IS OVERLAID ABOVE)
 
-	HB_DI
-	EX	(SP),HL		; save hl and get bank to restore in hl
-	PUSH	AF		; save af
-	LD	A,H		; bank to restore to a
-	CALL	HBX_BNKSEL	; restore it
-	POP	AF		; recover af
-	POP	HL		; recover hl
-	HB_EI
+	EX	(SP),HL		; SAVE HL AND GET BANK TO RESTORE IN HL
+	PUSH	AF		; SAVE AF
+	LD	A,H		; BANK TO RESTORE TO A
+	CALL	HBX_BNKSEL	; RESTORE IT
+	POP	AF		; RECOVER AF
+	POP	HL		; RECOVER HL
 	RET
 ;
 ; PEEK & POKE ROUTINES
 ;   ADDRESS IN HL, BANK IN D, VALUE IN/OUT IN E, A IS TRASHED
 ;
 HBX_PEEK:
+#IF (INTTYPE == IT_SIMH)
 	HB_DI
+#ENDIF
+	LD	(HBX_PPSP),SP	; SAVE ORIGINAL STACK FRAME
+	LD	SP,HBX_TMPSTK	; USE SMALL TEMP STACK FRAME IN HI MEM
 	LD	A,(HB_CURBNK)
 	PUSH	AF
 	LD	A,D	
@@ -400,7 +407,11 @@ HBX_PEEK:
 	JR	HBX_PPRET
 ;
 HBX_POKE:
+#IF (INTTYPE == IT_SIMH)
 	HB_DI
+#ENDIF
+	LD	(HBX_PPSP),SP	; SAVE ORIGINAL STACK FRAME
+	LD	SP,HBX_TMPSTK	; USE SMALL TEMP STACK FRAME IN HI MEM
 	LD	A,(HB_CURBNK)
 	PUSH	AF
 	LD	A,D	
@@ -410,14 +421,23 @@ HBX_POKE:
 HBX_PPRET:
 	POP	AF
 	CALL	HBX_BNKSEL
+	LD	SP,0		; RESTORE ORIGINAL STACK FRAME
+HBX_PPSP	.EQU	$ - 2
+#IF (INTTYPE == IT_SIMH)
 	HB_EI
+#ENDIF
 	RET
 ;
+; SMALL TEMPORARY STACK FOR USE BY HB_INVOKE
+;
+		.FILL	20,$CC		; 10 LEVEL STACK
+HBX_TMPSTK	.EQU	$
+;
 ; PRIVATE STACK AT END OF HBIOS CODE
 ; OCCUPIES SPACE BEFORE IVT
 ;
 HBX_STKSIZ	.EQU	$FF00 - $
-		.ECHO	"HBIOS STACK space: "
+		.ECHO	"HBIOS PROXY STACK space: "
 		.ECHO	HBX_STKSIZ
 		.ECHO	" bytes.\n"
 		.FILL	HBX_STKSIZ,$FF
@@ -464,33 +484,30 @@ INT_BAD:	; BAD INTERRUPT HANDLER
 ; 
 HBX_INT:	; COMMON INTERRUPT ROUTING CODE
 ;
-	; SAVE STATE (ASSUMES HL SAVED PREVIOUSLY)
+	LD	(HBX_INT_SP),SP		; SAVE ORIGINAL STACK FRAME
+	LD	SP,HBX_STACK		; USE STACK FRAME IN HI MEM
+
+	; SAVE STATE (HL SAVED PREVIOUSLY)
 	PUSH	AF			; SAVE AF
 	PUSH	BC			; SAVE BC
 	PUSH	DE			; SAVE DE
 
-	LD	(HBX_INT_SP),SP		; SAVE ORIGINAL STACK FRAME
-	LD	SP,HBX_STACK		; USE STACK FRAME IN HI MEM
-	
 	LD	A,BID_BIOS		; HBIOS BANK
 	CALL	HBX_BNKSEL_INT		; SELECT IT
 
-	;LD	SP,HB_ISTACK		; NOW USE INT STACK IN HBIOS BANK
-
 	CALL	JPHL			; CALL INTERRUPT ROUTINE
 
-	;LD	SP,HBX_STACK		; USE STACK FRAME IN HI MEM
-
 	LD	A,(HB_CURBNK)		; GET PRE-INT BANK
 	CALL	HBX_BNKSEL		; SELECT IT
 
-	LD	SP,$FFFF		; RESTORE ORIGINAL STACK FRAME
-HBX_INT_SP	.EQU	$ - 2
-
 	; RESTORE STATE
 	POP	DE			; RESTORE DE
 	POP	BC			; RESTORE BC
 	POP	AF			; RESTORE AF
+
+	LD	SP,$FFFF		; RESTORE ORIGINAL STACK FRAME
+HBX_INT_SP	.EQU	$ - 2
+
 	POP	HL			; RESTORE HL
 
 	EI				; ENABLE INTERRUPTS
@@ -536,15 +553,20 @@ HBX_BUF		.FILL	HBX_BUFSIZ,0
 ;   HBIOS CORE
 ;==================================================================================================
 ;
-HB_STKSIZ	.EQU	$60	; HBIOS PRIVATE STACK SIZE
-HB_ISTKSIZ	.EQU	$40	; HBIOS INTERRUPT STACK SIZE
-;
 ;==================================================================================================
-;   ENTRY VECTORS (JUMP TABLE)
+;   ENTRY VECTORS (JUMP TABLE) AND INTERNAL PROCESSING STACK
 ;==================================================================================================
+;
+HB_ENTRYTBL	.EQU	$
 ;
 	JP	HB_START		; HBIOS INITIALIZATION
 	JP	HB_DISPATCH		; VECTOR TO DISPATCHER
+;
+HB_STKSIZ	.EQU	HB_ENTRYTBL + 256 - $
+;
+		.FILL	HB_STKSIZ,$FF	; USE REMAINDER OF PAGE FOR HBIOS STACK
+HB_STACK	.EQU	$		; TOP OF HBIOS STACK
+
 ;
 ;==================================================================================================
 ;   SYSTEM INITIALIZATION
@@ -721,9 +743,14 @@ HB_START1:			; BNKCALL ARRIVES HERE, BUT NOW RUNNING IN RAM BANK
 ;
 	; SETUP TIMER INT VECTOR VIA INT MODE 1 IN PAGE ZERO
 	LD	A,$C3			; JP OPCODE
-	LD	($38),A			; ... AT INT VECTOR ADDRESS
+	;LD	($38),A			; ... AT INT VECTOR ADDRESS
+	LD	($30),A			; ... AT INT VECTOR ADDRESS
 	LD	HL,INT_TIMER		; ADDRESS OF TIMER INT HANDLER
-	LD	($39),HL		; ... IS TARGET OF JP
+	;LD	($39),HL		; ... IS TARGET OF JP
+	LD	($31),HL		; ... IS TARGET OF JP
+	
+	LD	HL,INT_TIMER
+	LD	(HBX_IVT),HL
 ;
 #ENDIF
 ;
@@ -2932,12 +2959,6 @@ HSTHEAD		.DB	0		; HEAD (0-255)
 HEAPCURB	.DW	0		; MARK HEAP ADDRESS AFTER INITIALIZATION
 ;
 HB_TICKS	.FILL	4,0		; 32 BIT TICK COUNTER
-;
-		.FILL	HB_STKSIZ,$FF	; 48 ENTRY STACK FOR HBIOS FUNCTION PROCESSING
-HB_STACK	.EQU	$		; TOP OF HBIOS STACK
-;;
-;		.FILL	HB_ISTKSIZ,$FF	; 32 ENTRY STACK FOR INTERRUPT PROCESSING
-;HB_ISTACK	.EQU	$		; TOP OF INTERRUPT PROCESSING STACK
 ;
 STR_BANNER	.DB	"RetroBrew HBIOS v", BIOSVER, ", ", TIMESTAMP, "$"
 STR_PLATFORM	.DB	PLATFORM_NAME, "$"
diff --git a/Source/Images/hd0/s1/u0/LDNZT.COM b/Source/Images/hd0/s1/u0/LDNZT.COM
new file mode 100644
index 00000000..535d8418
Binary files /dev/null and b/Source/Images/hd0/s1/u0/LDNZT.COM differ
diff --git a/Source/Images/hd0/s1/u0/STAMPS.DAT b/Source/Images/hd0/s1/u0/STAMPS.DAT
index 23cd9bd7..a312ae58 100644
Binary files a/Source/Images/hd0/s1/u0/STAMPS.DAT and b/Source/Images/hd0/s1/u0/STAMPS.DAT differ
diff --git a/Source/ZSDOS/Clock/LDNZT.COM b/Source/ZSDOS/Clock/LDNZT.COM
new file mode 100644
index 00000000..535d8418
Binary files /dev/null and b/Source/ZSDOS/Clock/LDNZT.COM differ
diff --git a/Source/ZSDOS/Clock/ReadMe.txt b/Source/ZSDOS/Clock/ReadMe.txt
index 925ae7bb..05aaa67a 100644
--- a/Source/ZSDOS/Clock/ReadMe.txt
+++ b/Source/ZSDOS/Clock/ReadMe.txt
@@ -5,3 +5,5 @@ The hbclk.z80 source file can be compiled using Build.cmd which will produce a r
 The relocatable binary should be added/updated in the stamps.dat libary.  The stamps.dat file is just a standard LU type library and is easily updated using NULU.  The members are the relocatable binaries, but with the .REL extension removed.
 
 SETUPZST is used to create runnable executable (.COM) files.  An executable has been created for DateStamper (LDDS.COM) and P2DOS (LDP2D.COM).  The executables are all configured for operation as an RSX (resident system extension).
+
+The STAMPS.DAT file here is a version that I cobbled together.  Using the STAMPS.DAT file included in the ZSDOS distribution results in a load file that does not work.  It claims to load, but is not present.  I found a "fixed" version of STAMPS.DAT on the Walnut Creek CD-ROM which works, but was missing the NZ and NZP2 stamp variants.  So, I added those variants to the working version of STAMPS.DAT which is included here.
diff --git a/Source/ZSDOS/Clock/STAMPS.DAT b/Source/ZSDOS/Clock/STAMPS.DAT
new file mode 100644
index 00000000..a312ae58
Binary files /dev/null and b/Source/ZSDOS/Clock/STAMPS.DAT differ
diff --git a/Tools/simh/Sim.cfg b/Tools/simh/Sim.cfg
index c4b8a747..06ae10a0 100644
--- a/Tools/simh/Sim.cfg
+++ b/Tools/simh/Sim.cfg
@@ -33,8 +33,11 @@ set hdsk0 wrtenb
 set hdsk1 wrtenb
 
 ; enable timer interrupt, 50Hz
+; DDT, SID, etc. use the normal IM 1 vector 6 ($38)
+; for breakpoints so we use vector 6 ($30)
 d timd 20
-d timh 38
+;d timh 38
+d timh 30
 set simh timeron
 
 ; start emulation