diff --git a/Makefile b/Makefile
index 27a67a7..cf1d128 100644
--- a/Makefile
+++ b/Makefile
@@ -1,11 +1,15 @@
 BUILDDIR=.build
-_BIN= rom_monitor.bin ram_monitor.bin cpm22.bin bios.bin putsys.bin loader.bin MONITOR.COM
+_BIN= cpm22.bin bios.bin
 BIN = $(patsubst %,$(BUILDDIR)/%,$(_BIN))
 
-$(BUILDDIR)/%.bin: src/%.z80
+.PHONY: all clean
+
+all: $(BUILDDIR) $(BIN)
+
+$(BUILDDIR)/%.bin: src/%.z80 | $(BUILDDIR) 
 	@zasm -w -i $< -o $@
 
-$(BUILDDIR)/%.COM: src/%.z80
+$(BUILDDIR)/%.COM: src/%.z80 | $(BUILDDIR)
 	@zasm -w -i $< -o $@
 
 $(BUILDDIR):
@@ -13,6 +17,5 @@ $(BUILDDIR):
 
 all: $(BUILDDIR) $(BIN)
 
-.PHONY: clean
 clean:
 	@rm -df $(BUILDDIR)/*.bin $(BUILDDIR)/*.COM $(BUILDDIR)/*.lst .build
diff --git a/bin/ASM.COM b/bin/ASM.COM
deleted file mode 100644
index a63e5ae..0000000
Binary files a/bin/ASM.COM and /dev/null differ
diff --git a/bin/DDT.COM b/bin/DDT.COM
deleted file mode 100644
index 70e4ebf..0000000
Binary files a/bin/DDT.COM and /dev/null differ
diff --git a/bin/DISKDEF.LIB b/bin/DISKDEF.LIB
deleted file mode 100644
index 221fa21..0000000
--- a/bin/DISKDEF.LIB
+++ /dev/null
@@ -1,251 +0,0 @@
-;	CP/M 2.0 disk re-definition library
-;
-;	Copyright (c) 1979
-;	Digital Research
-;	Box 579
-;	Pacific Grove, CA
-;	93950
-;
-;	CP/M logical disk drives are defined using the
-;	macros given below, where the sequence of calls
-;	is:
-;
-;	disks	n
-;	diskdef	parameter-list-0
-;	diskdef	parameter-list-1
-;	...
-;	diskdef	parameter-list-n
-;	endef
-;
-;	where n is the number of logical disk drives attached
-;	to the CP/M system, and parameter-list-i defines the
-;	characteristics of the ith drive (i=0,1,...,n-1)
-;
-;	each parameter-list-i takes the form
-;		dn,fsc,lsc,[skf],bls,dks,dir,cks,ofs,[0]
-;	where
-;	dn	is the disk number 0,1,...,n-1
-;	fsc	is the first sector number (usually 0 or 1)
-;	lsc	is the last sector number on a track
-;	skf	is optional "skew factor" for sector translate
-;	bls	is the data block size (1024,2048,...,16384)
-;	dks	is the disk size in bls increments (word)
-;	dir	is the number of directory elements (word)
-;	cks	is the number of dir elements to checksum
-;	ofs	is the number of tracks to skip (word)
-;	[0]	is an optional 0 which forces 16K/directory entry
-;
-;	for convenience, the form
-;		dn,dm
-;	defines disk dn as having the same characteristics as
-;	a previously defined disk dm.
-;
-;	a standard four drive CP/M system is defined by
-;		disks	4
-;		diskdef	0,1,26,6,1024,243,64,64,2
-;	dsk	set	0
-;		rept	3
-;	dsk	set	dsk+1
-;		diskdef	%dsk,0
-;		endm
-;		endef
-;
-;	the value of "begdat" at the end of assembly defines the
-;	beginning of the uninitialize ram area above the bios,
-;	while the value of "enddat" defines the next location
-;	following the end of the data area.  the size of this
-;	area is given by the value of "datsiz" at the end of the
-;	assembly.  note that the allocation vector will be quite
-;	large if a large disk size is defined with a small block
-;	size.
-;
-dskhdr	macro	dn
-;;	define a single disk header list
-dpe&dn:	dw	xlt&dn,0000h	;translate table
-	dw	0000h,0000h	;scratch area
-	dw	dirbuf,dpb&dn	;dir buff,parm block
-	dw	csv&dn,alv&dn	;check, alloc vectors
-	endm
-;
-disks	macro	nd
-;;	define nd disks
-ndisks	set	nd	;;for later reference
-dpbase	equ	$	;base of disk parameter blocks
-;;	generate the nd elements
-dsknxt	set	0
-	rept	nd
-	dskhdr	%dsknxt
-dsknxt	set	dsknxt+1
-	endm
-	endm
-;
-dpbhdr	macro	dn
-dpb&dn	equ	$		;disk parm block
-	endm
-;
-ddb	macro	data,comment
-;;	define a db statement
-	db	data		comment
-	endm
-;
-ddw	macro	data,comment
-;;	define a dw statement
-	dw	data		comment
-	endm
-;
-gcd	macro	m,n
-;;	greatest common divisor of m,n
-;;	produces value gcdn as result
-;;	(used in sector translate table generation)
-gcdm	set	m	;;variable for m
-gcdn	set	n	;;variable for n
-gcdr	set	0	;;variable for r
-	rept	65535
-gcdx	set	gcdm/gcdn
-gcdr	set	gcdm - gcdx*gcdn
-	if	gcdr = 0
-	exitm
-	endif
-gcdm	set	gcdn
-gcdn	set	gcdr
-	endm
-	endm
-;
-diskdef	macro	dn,fsc,lsc,skf,bls,dks,dir,cks,ofs,k16
-;;	generate the set statements for later tables
-	if	nul lsc
-;;	current disk dn same as previous fsc
-dpb&dn	equ	dpb&fsc	;equivalent parameters
-als&dn	equ	als&fsc	;same allocation vector size
-css&dn	equ	css&fsc	;same checksum vector size
-xlt&dn	equ	xlt&fsc	;same translate table
-	else
-secmax	set	lsc-(fsc)	;;sectors 0...secmax
-sectors	set	secmax+1;;number of sectors
-als&dn	set	(dks)/8	;;size of allocation vector
-	if	((dks) mod 8) ne 0
-als&dn	set	als&dn+1
-	endif
-css&dn	set	(cks)/4	;;number of checksum elements
-;;	generate the block shift value
-blkval	set	bls/128	;;number of sectors/block
-blkshf	set	0	;;counts right 0's in blkval
-blkmsk	set	0	;;fills with 1's from right
-	rept	16	;;once for each bit position
-	if	blkval=1
-	exitm
-	endif
-;;	otherwise, high order 1 not found yet
-blkshf	set	blkshf+1
-blkmsk	set	(blkmsk shl 1) or 1
-blkval	set	blkval/2
-	endm
-;;	generate the extent mask byte
-blkval	set	bls/1024	;;number of kilobytes/block
-extmsk	set	0	;;fill from right with 1's
-	rept	16
-	if	blkval=1
-	exitm
-	endif
-;;	otherwise more to shift
-extmsk	set	(extmsk shl 1) or 1
-blkval	set	blkval/2
-	endm
-;;	may be double byte allocation
-	if	(dks) > 256
-extmsk	set	(extmsk shr 1)
-	endif
-;;	may be optional [0] in last position
-	if	not nul k16
-extmsk	set	k16
-	endif
-;;	now generate directory reservation bit vector
-dirrem	set	dir	;;# remaining to process
-dirbks	set	bls/32	;;number of entries per block
-dirblk	set	0	;;fill with 1's on each loop
-	rept	16
-	if	dirrem=0
-	exitm
-	endif
-;;	not complete, iterate once again
-;;	shift right and add 1 high order bit
-dirblk	set	(dirblk shr 1) or 8000h
-	if	dirrem > dirbks
-dirrem	set	dirrem-dirbks
-	else
-dirrem	set	0
-	endif
-	endm
-	dpbhdr	dn	;;generate equ $
-	ddw	%sectors,<;sec per track>
-	ddb	%blkshf,<;block shift>
-	ddb	%blkmsk,<;block mask>
-	ddb	%extmsk,<;extnt mask>
-	ddw	%(dks)-1,<;disk size-1>
-	ddw	%(dir)-1,<;directory max>
-	ddb	%dirblk shr 8,<;alloc0>
-	ddb	%dirblk and 0ffh,<;alloc1>
-	ddw	%(cks)/4,<;check size>
-	ddw	%ofs,<;offset>
-;;	generate the translate table, if requested
-	if	nul skf
-xlt&dn	equ	0		;no xlate table
-	else
-	if	skf = 0
-xlt&dn	equ	0		;no xlate table
-	else
-;;	generate the translate table
-nxtsec	set	0	;;next sector to fill
-nxtbas	set	0	;;moves by one on overflow
-	gcd	%sectors,skf
-;;	gcdn = gcd(sectors,skew)
-neltst	set	sectors/gcdn
-;;	neltst is number of elements to generate
-;;	before we overlap previous elements
-nelts	set	neltst	;;counter
-xlt&dn	equ	$		;translate table
-	rept	sectors	;;once for each sector
-	if	sectors < 256
-	ddb	%nxtsec+(fsc)
-	else
-	ddw	%nxtsec+(fsc)
-	endif
-nxtsec	set	nxtsec+(skf)
-	if	nxtsec >= sectors
-nxtsec	set	nxtsec-sectors
-	endif
-nelts	set	nelts-1
-	if	nelts = 0
-nxtbas	set	nxtbas+1
-nxtsec	set	nxtbas
-nelts	set	neltst
-	endif
-	endm
-	endif	;;end of nul fac test
-	endif	;;end of nul bls test
-	endm
-;
-defds	macro	lab,space
-lab:	ds	space
-	endm
-;
-lds	macro	lb,dn,val
-	defds	lb&dn,%val&dn
-	endm
-;
-endef	macro
-;;	generate the necessary ram data areas
-begdat	equ	$
-dirbuf:	ds	128	;directory access buffer
-dsknxt	set	0
-	rept	ndisks	;;once for each disk
-	lds	alv,%dsknxt,als
-	lds	csv,%dsknxt,css
-dsknxt	set	dsknxt+1
-	endm
-enddat	equ	$
-datsiz	equ	$-begdat
-;;	db 0 at this point forces hex record
-	endm
-;
-
\ No newline at end of file
diff --git a/bin/DSKMAINT.COM b/bin/DSKMAINT.COM
deleted file mode 100644
index 9d33a89..0000000
Binary files a/bin/DSKMAINT.COM and /dev/null differ
diff --git a/bin/DUMP.COM b/bin/DUMP.COM
deleted file mode 100644
index 03a77c3..0000000
Binary files a/bin/DUMP.COM and /dev/null differ
diff --git a/bin/ED.COM b/bin/ED.COM
deleted file mode 100644
index a0f0f54..0000000
Binary files a/bin/ED.COM and /dev/null differ
diff --git a/bin/LOAD.COM b/bin/LOAD.COM
deleted file mode 100644
index b9601e0..0000000
Binary files a/bin/LOAD.COM and /dev/null differ
diff --git a/bin/MAC.COM b/bin/MAC.COM
deleted file mode 100644
index cb0ac80..0000000
Binary files a/bin/MAC.COM and /dev/null differ
diff --git a/bin/MBASIC.COM b/bin/MBASIC.COM
deleted file mode 100644
index c9ec3cd..0000000
Binary files a/bin/MBASIC.COM and /dev/null differ
diff --git a/bin/PIP.COM b/bin/PIP.COM
deleted file mode 100644
index 4b2ce4b..0000000
Binary files a/bin/PIP.COM and /dev/null differ
diff --git a/bin/STAT.COM b/bin/STAT.COM
deleted file mode 100644
index 1de359f..0000000
Binary files a/bin/STAT.COM and /dev/null differ
diff --git a/bin/SUBMIT.COM b/bin/SUBMIT.COM
deleted file mode 100644
index 2e78882..0000000
Binary files a/bin/SUBMIT.COM and /dev/null differ
diff --git a/bin/XSUB.COM b/bin/XSUB.COM
deleted file mode 100644
index 15e86ab..0000000
Binary files a/bin/XSUB.COM and /dev/null differ
diff --git a/bin/s.com b/bin/s.com
deleted file mode 100644
index c1c8170..0000000
Binary files a/bin/s.com and /dev/null differ
diff --git a/bin/BIOS.ASM b/ref/BIOS.ASM
similarity index 100%
rename from bin/BIOS.ASM
rename to ref/BIOS.ASM
diff --git a/bin/CPM.SYS b/ref/CPM.SYS
similarity index 100%
rename from bin/CPM.SYS
rename to ref/CPM.SYS
diff --git a/bin/DEBLOCK.ASM b/ref/DEBLOCK.ASM
similarity index 100%
rename from bin/DEBLOCK.ASM
rename to ref/DEBLOCK.ASM
diff --git a/bin/DUMP.ASM b/ref/DUMP.ASM
similarity index 100%
rename from bin/DUMP.ASM
rename to ref/DUMP.ASM
diff --git a/src/MONITOR.z80 b/src/MONITOR.z80
deleted file mode 100644
index ec083b8..0000000
--- a/src/MONITOR.z80
+++ /dev/null
@@ -1,696 +0,0 @@
-#target bin
-;RAM monitor for a system with serial interface and IDE disk and memory expansion board.
-;This program to be loaded by CP/M at 0100h, then it copies itself to memory at DC00h.
-;Assumes serial port has been initialized by ROM monitor.
-;Assumes the UART data port address is 02h and control/status address is 03h
-;Assumes memory configuration is all-RAM
-;
-;The subroutines use these variables in RAM, same area as ROM monitor:
-current_location:	equ	0xE100		;word variable in RAM
-line_count:		equ	0xE102		;byte variable in RAM
-byte_count:		equ	0xE103		;byte variable in RAM
-value_pointer:		equ	0xE104		;word variable in RAM
-current_value:		equ	0xE106		;word variable in RAM
-buffer:			equ	0xE108		;buffer in RAM -- up to stack area
-;Will use stack of calling program (CP/M) which is re-initialized at re-boot.
-;
-;
-;
-;Code to start program and move to higher memory
-;
-#code BOOT, 0x0100
-			ld	hl,code_origin	;start of code to transfer
-			ld	bc,code_end-code_start+1	;length of code to transfer
-			ld	de,0E200h	;target of transfer
-			ldir			;Z80 transfer instruction
-			jp	0E200h
-code_origin:					;address of first byte of code before transfer
-;	
-#code MAIN, 0xE200
-code_start:		jp 	monitor_start			
-;
-;Puts a single char (byte value) on serial output
-;Call with char to send in A register. Uses B register
-write_char:		ld	b,a			;store char
-write_char_loop:	in	a,(3)			;check if OK to send
-			and	001h			;check TxRDY bit
-			jp 	z,write_char_loop	;loop if not set
-			ld 	a,b			;get char back
-			out 	(2),a			;send to output
-			ret				;returns with char in a
-;
-;Subroutine to write a zero-terminated string to serial output
-;Pass address of string in HL register
-;No error checking
-write_string:		in 	a,(3)			;read status
-			and 	001h			;check TxRDY bit
-			jp 	z,write_string		;loop if not set
-			ld 	a,(hl)			;get char from string
-			and 	a			;check if 0
-			ret 	z			;yes, finished
-			out 	(2),a			;no, write char to output
-			inc 	hl			;next char in string
-			jp 	write_string		;start over
-;
-;Binary loader. Receive a binary file, place in memory.
-;Address of load passed in HL, length of load (= file length) in BC
-bload:			in 	a,(0x1F)			;get status
-			and 	001h			;check RxRDY bit
-			jp 	z,bload			;not ready, loop
-			in	a,(0x1E)
-			ld	(hl),a
-			inc	hl
-			dec	bc			;byte counter
-			ld	a,b			;need to test BC this way because
-			or	c			;dec rp instruction does not change flags
-			jp	nz,bload
-			ret
-;
-;Binary dump to port. Send a stream of binary data from memory to serial output
-;Address of dump passed in HL, length of dump in BC
-bdump:			in 	a,(3)			;get status
-			and 	001h			;check TxRDY bit
-			jp 	z,bdump			;not ready, loop
-			ld	a,(hl)
-			out	(2),a
-			inc	hl
-			dec	bc
-			ld	a,b			;need to test this way because
-			or	c			;dec rp instruction does not change flags
-			jp	nz,bdump
-			ret
-;
-;Subroutine to get a string from serial input, place in buffer.
-;Buffer address passed in HL reg.
-;Uses A,BC,DE,HL registers (including calls to other subroutines).
-;Line entry ends by hitting return key. Return char not included in string (replaced by zero).
-;Backspace editing OK. No error checking.
-;
-get_line:		ld	c,000h			;line position
-			ld	a,h			;put original buffer address in de
-			ld	d,a			;after this don't need to preserve hl
-			ld	a,l			;subroutines called don't use de
-			ld	e,a
-get_line_next_char:	in 	a,(0x1F)			;get status
-			and 	001h			;check RxRDY bit
-			jp 	z,get_line_next_char	;not ready, loop
-			in 	a,(0x1E)			;get char
-			cp	00dh			;check if return
-			ret	z			;yes, normal exit
-			cp	07fh			;check if backspace (VT102 keys)
-			jp	z,get_line_backspace	;yes, jump to backspace routine
-			cp	008h			;check if backspace (ANSI keys)
-			jp	z,get_line_backspace	;yes, jump to backspace
-			call	write_char		;put char on screen
-			ld	(de),a			;store char in buffer
-			inc	de			;point to next space in buffer
-			inc	c			;inc counter
-			ld	a,000h
-			ld	(de),a			;leaves a zero-terminated string in buffer
-			jp	get_line_next_char
-get_line_backspace:	ld	a,c			;check current position in line
-			cp	000h			;at beginning of line?
-			jp	z,get_line_next_char	;yes, ignore backspace, get next char
-			dec	de			;no, erase char from buffer
-			dec	c			;back up one
-			ld	a,000h			;put a zero in buffer where the last char was
-			ld	(de),a
-			ld	hl,erase_char_string	;ANSI sequence to delete one char from line
-			call	write_string		;transmits sequence to backspace and erase char
-			jp	get_line_next_char
-;
-;Creates a two-char hex string from the byte value passed in register A
-;Location to place string passed in HL
-;String is zero-terminated, stored in 3 locations starting at HL
-;Also uses registers b,d, and e
-byte_to_hex_string:	ld	b,a			;store original byte
-			srl	a			;shift right 4 times, putting
-			srl	a			;high nybble in low-nybble spot
-			srl	a			;and zeros in high-nybble spot
-			srl	a
-			ld	d,000h			;prepare for 16-bit addition
-			ld	e,a			;de contains offset
-			push	hl			;temporarily store string target address
-			ld	hl,hex_char_table	;use char table to get high-nybble character
-			add	hl,de			;add offset to start of table
-			ld	a,(hl)			;get char
-			pop	hl			;get string target address
-			ld	(hl),a			;store first char of string
-			inc	hl			;point to next string target address
-			ld	a,b			;get original byte back from reg b
-			and	00fh			;mask off high-nybble
-			ld	e,a			;d still has 000h, now de has offset
-			push	hl			;temp store string target address
-			ld	hl,hex_char_table	;start of table
-			add	hl,de			;add offset
-			ld	a,(hl)			;get char
-			pop	hl			;get string target address
-			ld	(hl),a			;store second char of string
-			inc	hl			;point to third location
-			ld	a,000h			;zero to terminate string
-			ld	(hl),a			;store the zero
-			ret				;done
-;
-;Converts a single ASCII hex char to a nybble value
-;Pass char in reg A. Letter numerals must be upper case.
-;Return nybble value in low-order reg A with zeros in high-order nybble if no error.
-;Return 0ffh in reg A if error (char not a valid hex numeral).
-;Also uses b, c, and hl registers.
-hex_char_to_nybble:	ld	hl,hex_char_table
-			ld	b,00fh			;no. of valid characters in table - 1.
-			ld	c,000h			;will be nybble value
-hex_to_nybble_loop:	cp	(hl)			;character match here?
-			jp	z,hex_to_nybble_ok	;match found, exit
-			dec	b			;no match, check if at end of table
-			jp	m,hex_to_nybble_err	;table limit exceded, exit with error
-			inc	c			;still inside table, continue search
-			inc	hl
-			jp	hex_to_nybble_loop
-hex_to_nybble_ok:	ld	a,c			;put nybble value in a
-			ret
-hex_to_nybble_err:	ld	a,0ffh			;error value
-			ret
-;
-;Converts a hex character pair to a byte value
-;Called with location of high-order char in HL
-;If no error carry flag clear, returns with byte value in register A, and
-;HL pointing to next mem location after char pair.
-;If error (non-hex char) carry flag set, HL pointing to invalid char
-hex_to_byte:		ld	a,(hl)			;location of character pair
-			push	hl			;store hl (hex_char_to_nybble uses it)
-			call	hex_char_to_nybble
-			pop	hl			;returns with nybble value in a reg, or 0ffh if error
-			cp	0ffh			;non-hex character?
-			jp	z,hex_to_byte_err	;yes, exit with error
-			sla	a			;no, move low order nybble to high side
-			sla	a
-			sla	a
-			sla	a
-			ld	d,a			;store high-nybble
-			inc	hl			;get next character of the pair
-			ld	a,(hl)
-			push	hl			;store hl
-			call	hex_char_to_nybble
-			pop	hl
-			cp	0ffh			;non-hex character?
-			jp	z,hex_to_byte_err	;yes, exit with error
-			or	d			;no, combine with high-nybble
-			inc	hl			;point to next memory location after char pair
-			scf
-			ccf				;no-error exit (carry = 0)
-			ret
-hex_to_byte_err:	scf				;error, carry flag set
-			ret
-hex_char_table:		defm	"0123456789ABCDEF"	;ASCII hex table
-;
-;Subroutine to get a two-byte address from serial input.
-;Returns with address value in HL
-;Uses locations in RAM for buffer and variables
-address_entry:		ld	hl,buffer		;location for entered string
-			call	get_line		;returns with address string in buffer
-			ld	hl,buffer		;location of stored address entry string
-			call	hex_to_byte		;will get high-order byte first
-			jp	c, address_entry_error	;if error, jump
-			ld	(current_location+1),a	;store high-order byte, little-endian
-			ld	hl,buffer+2		;point to low-order hex char pair
-			call	hex_to_byte		;get low-order byte
-			jp	c, address_entry_error	;jump if error
-			ld	(current_location),a	;store low-order byte in lower memory
-			ld	hl,(current_location)	;put memory address in hl
-			ret
-address_entry_error:	ld	hl,address_error_msg
-			call	write_string
-			jp	address_entry
-;
-;Subroutine to get a decimal string, return a word value
-;Calls decimal_string_to_word subroutine
-decimal_entry:		ld	hl,buffer
-			call	get_line		;returns with DE pointing to terminating zero
-			ld	hl,buffer
-			call	decimal_string_to_word
-			ret	nc			;no error, return with word in hl
-			ld	hl,decimal_error_msg	;error, try again
-			call	write_string
-			jp	decimal_entry
-;
-;Subroutine to convert a decimal string to a word value
-;Call with address of string in HL, pointer to end of string in DE
-;Carry flag set if error (non-decimal char)
-;Carry flag clear, word value in HL if no error.
-decimal_string_to_word:	ld	b,d
-			ld	c,e			;use BC as string pointer
-			ld	(current_location),hl	;store addr. of start of buffer in RAM word variable
-			ld	hl,000h			;starting value zero
-			ld	(current_value),hl
-			ld	hl,decimal_place_value	;pointer to values
-			ld	(value_pointer),hl
-decimal_next_char:	dec	bc			;next char in string (moving right to left)
-			ld	hl,(current_location)	;check if at end of decimal string
-			scf				;get ready to subtract de from buffer addr.
-			ccf				;set carry to zero (clear)
-			sbc	hl,bc			;keep going if bc > or = hl (buffer address)
-			jp	c,decimal_continue	;borrow means bc > hl
-			jp	z,decimal_continue	;z means bc = hl
-			ld	hl,(current_value)	;return if de < buffer address (no borrow)
-			scf				;get value back from RAM variable
-			ccf
-			ret				;return with carry clear, value in hl
-decimal_continue:	ld	a,(bc)			;next char in string (right to left)
-			sub	030h			;ASCII value of zero char
-			jp	m,decimal_error		;error if char value less than 030h
-			cp	00ah			;error if byte value > or = 10 decimal
-			jp	p,decimal_error		;a reg now has value of decimal numeral
-			ld	hl,(value_pointer)	;get value to add an put in de
-			ld	e,(hl)			;little-endian (low byte in low memory)
-			inc	hl
-			ld	d,(hl)
-			inc	hl			;hl now points to next value
-			ld	(value_pointer),hl
-			ld	hl,(current_value)	;get back current value
-decimal_add:		dec	a			;add loop to increase total value
-			jp	m,decimal_add_done	;end of multiplication
-			add	hl,de
-			jp	decimal_add
-decimal_add_done:	ld	(current_value),hl
-			jp	decimal_next_char
-decimal_error:		scf
-			ret
-			jp	decimal_add
-decimal_place_value:	defw	1,10,100,1000,10000
-;
-;Memory dump
-;Displays a 256-byte block of memory in 16-byte rows.
-;Called with address of start of block in HL
-memory_dump:		ld	(current_location),hl	;store address of block to be displayed
-			ld	a,000h
-			ld	(byte_count),a		;initialize byte count
-			ld	(line_count),a		;initialize line count
-			jp	dump_new_line
-dump_next_byte:		ld	hl,(current_location)	;get byte address from storage,
-			ld	a,(hl)			;get byte to be converted to string
-			inc	hl			;increment address and
-			ld	(current_location),hl	;store back
-			ld	hl,buffer		;location to store string
-			call	byte_to_hex_string	;convert
-			ld	hl,buffer		;display string
-			call	write_string
-			ld	a,(byte_count)		;next byte
-			inc	a
-			jp	z,dump_done		;stop when 256 bytes displayed
-			ld	(byte_count),a		;not finished yet, store
-			ld	a,(line_count)		;end of line (16 characters)?
-			cp	00fh			;yes, start new line
-			jp	z,dump_new_line
-			inc	a			;no, increment line count
-			ld	(line_count),a
-			ld	a,020h			;print space
-			call	write_char
-			jp	dump_next_byte		;continue
-dump_new_line:		ld	a,000h			;reset line count to zero
-			ld	(line_count),a			
-			call	write_newline
-			ld	hl,(current_location)	;location of start of line
-			ld	a,h			;high byte of address
-			ld	hl, buffer
-			call	byte_to_hex_string	;convert
-			ld	hl,buffer
-			call	write_string		;write high byte
-			ld	hl,(current_location)
-			ld	a,l			;low byte of address
-			ld	hl, buffer
-			call	byte_to_hex_string	;convert
-			ld	hl,buffer
-			call	write_string		;write low byte
-			ld	a,020h			;space
-			call	write_char
-			jp	dump_next_byte		;now write 16 bytes
-dump_done:		ld	a,000h
-			ld	hl,buffer
-			ld	(hl),a			;clear buffer of last string
-			call	write_newline
-			ret
-;
-;Memory load
-;Loads RAM memory with bytes entered as hex characters
-;Called with address to start loading in HL
-;Displays entered data in 16-byte rows.
-memory_load:		ld	(current_location),hl
-			ld	hl,data_entry_msg
-			call	write_string
-			jp	load_new_line
-load_next_char:		call	get_char
-			cp	00dh			;return?
-			jp	z,load_done		;yes, quit
-			ld	(buffer),a
-			call	get_char
-			cp	00dh			;return?
-			jp	z,load_done		;yes, quit
-			ld	(buffer+1),a
-			ld	hl,buffer
-			call	hex_to_byte
-			jp	c,load_data_entry_error	;non-hex character
-			ld	hl,(current_location)	;get byte address from storage,
-			ld	(hl),a			;store byte
-			inc	hl			;increment address and
-			ld	(current_location),hl	;store back
-			ld	a,(buffer)
-			call	write_char
-			ld	a,(buffer+1)
-			call	write_char
-			ld	a,(line_count)		;end of line (16 characters)?
-			cp	00fh			;yes, start new line
-			jp	z,load_new_line
-			inc	a			;no, increment line count
-			ld	(line_count),a
-			ld	a,020h			;print space
-			call	write_char
-			jp	load_next_char		;continue
-load_new_line:		ld	a,000h			;reset line count to zero
-			ld	(line_count),a
-			call	write_newline
-			jp	load_next_char		;continue
-load_data_entry_error:	call	write_newline
-			ld	hl,data_error_msg
-			call	write_string
-			ret
-load_done:		call	write_newline
-			ret
-;
-;Get one ASCII character from the serial port.
-;Returns with char in A reg. No error checking.
-get_char:		in 	a,(0x1F)			;get status
-			and 	001h			;check RxRDY bit
-			jp 	z,get_char		;not ready, loop
-			in 	a,(0x1E)			;get char
-			ret
-;
-;Subroutine to start a new line
-write_newline:		ld	a,00dh			;ASCII carriage return character
-			call	write_char
-			ld	a,00ah			;new line (line feed) character
-			call	write_char
-			ret
-;
-;Subroutine to read one disk sector (128 bytes)
-;Address to place data passed in HL
-;LBA bits 0 to 7 passed in C, bits 8 to 15 passed in B
-;LBA bits 16 to 23 passed in E
-disk_read:
-rd_status_loop_1:	in	a,(0fh)		;check status
-			and	80h		;check BSY bit
-			jp	nz,rd_status_loop_1	;loop until not busy
-rd_status_loop_2:	in	a,(0fh)		;check	status
-			and	40h		;check DRDY bit
-			jp	z,rd_status_loop_2	;loop until ready
-			ld	a,01h		;number of sectors = 1
-			out	(0ah),a		;sector count register
-			ld	a,c
-			out	(0bh),a		;lba bits 0 - 7
-			ld	a,b
-			out	(0ch),a		;lba bits 8 - 15
-			ld	a,e
-			out	(0dh),a		;lba bits 16 - 23
-			ld	a,11100000b	;LBA mode, select drive 0
-			out	(0eh),a		;drive/head register
-			ld	a,20h		;Read sector command
-			out	(0fh),a
-rd_wait_for_DRQ_set:	in	a,(0fh)		;read status
-			and	08h		;DRQ bit
-			jp	z,rd_wait_for_DRQ_set	;loop until bit set
-rd_wait_for_BSY_clear:	in	a,(0fh)
-			and	80h
-			jp	nz,rd_wait_for_BSY_clear
-			in	a,(0fh)		;clear INTRQ
-read_loop:		in	a,(08h)		;get data
-			ld	(hl),a
-			inc	hl
-			in	a,(0fh)		;check status
-			and	08h		;DRQ bit
-			jp	nz,read_loop	;loop until cleared
-			ret
-;
-;Subroutine to write one disk sector (128 bytes)
-;Address of data to write to disk passed in HL
-;LBA bits 0 to 7 passed in C, bits 8 to 15 passed in B
-;LBA bits 16 to 23 passed in E
-disk_write:
-wr_status_loop_1:	in	a,(0fh)		;check status
-			and	80h		;check BSY bit
-			jp	nz,wr_status_loop_1	;loop until not busy
-wr_status_loop_2:	in	a,(0fh)		;check	status
-			and	40h		;check DRDY bit
-			jp	z,wr_status_loop_2	;loop until ready
-			ld	a,01h		;number of sectors = 1
-			out	(0ah),a		;sector count register
-			ld	a,c
-			out	(0bh),a		;lba bits 0 - 7
-			ld	a,b
-			out	(0ch),a		;lba bits 8 - 15
-			ld	a,e
-			out	(0dh),a		;lba bits 16 - 23
-			ld	a,11100000b	;LBA mode, select drive 0
-			out	(0eh),a		;drive/head register
-			ld	a,30h		;Write sector command
-			out	(0fh),a
-wr_wait_for_DRQ_set:	in	a,(0fh)		;read status
-			and	08h		;DRQ bit
-			jp	z,wr_wait_for_DRQ_set	;loop until bit set			
-write_loop:		ld	a,(hl)
-			out	(08h),a		;write data
-			inc	hl
-			in	a,(0fh)		;read status
-			and	08h		;check DRQ bit
-			jp	nz,write_loop	;write until bit cleared
-wr_wait_for_BSY_clear:	in	a,(0fh)
-			and	80h
-			jp	nz,wr_wait_for_BSY_clear
-			in	a,(0fh)		;clear INTRQ
-			ret
-;
-;Strings used in subroutines
-length_entry_string:	defm	"Enter length of file to load (decimal): ",0
-dump_entry_string:	defm	"Enter no. of bytes to dump (decimal): ",0
-LBA_entry_string:	defm	"Enter LBA (decimal, 0 to 65535): ",0
-erase_char_string:	defm	008h,01bh,"[K",000h	;ANSI sequence for backspace, erase to end of line.
-address_entry_msg:	defm	"Enter 4-digit hex address (use upper-case A through F): ",0
-address_error_msg:	defm	13,10,"Error: invalid hex character, try again: ",0
-data_entry_msg:		defm	"Enter hex bytes, hit return when finished.",13,10,0
-data_error_msg:		defm	"Error: invalid hex byte.",13,10,0
-decimal_error_msg:	defm	13,10,"Error: invalid decimal number, try again: ",0
-;
-;Simple monitor program for CPUville Z80 computer with serial interface.
-
-monitor_start:		call	write_newline		;routine program return here to avoid re-initialization of port
-			ld	a,03eh			;cursor symbol
-			call	write_char
-			ld	hl,buffer
-			call	get_line		;get monitor input string (command)
-			call	write_newline
-			call	parse			;interprets command, returns with address to jump to in HL
-			jp	(hl)
-;
-;Parses an input line stored in buffer for available commands as described in parse table.
-;Returns with address of jump to action for the command in HL
-parse:			ld	bc,parse_table		;bc is pointer to parse_table
-parse_start:		ld	a,(bc)			;get pointer to match string from parse table
-			ld	e,a
-			inc	bc
-			ld	a,(bc)			
-			ld	d,a			;de will is pointer to strings for matching
-			ld	a,(de)			;get first char from match string
-			or	000h			;zero?
-			jp	z,parser_exit		;yes, exit no_match
-			ld	hl,buffer		;no, parse input string 
-match_loop:		cp	(hl)			;compare buffer char with match string char
-			jp	nz,no_match		;no match, go to next match string
-			or	000h			;end of strings (zero)?
-			jp	z,parser_exit		;yes, matching string found
-			inc	de			;match so far, point to next char in match string
-			ld	a,(de)			;get next character from match string
-			inc	hl			;and point to next char in input string
-			jp	match_loop		;check for match
-no_match:		inc	bc			;skip over jump target to
-			inc	bc
-			inc	bc			;get address of next matching string
-			jp	parse_start
-parser_exit:		inc	bc			;skip to address of jump for match
-			ld	a,(bc)
-			ld	l,a
-			inc	bc
-			ld	a,(bc)
-			ld	h,a			;returns with jump address in hl
-			ret
-;
-;Actions to be taken on match
-;
-;Memory dump program
-;Input 4-digit hexadecimal address
-;Calls memory_dump subroutine
-dump_jump:		ld	hl,dump_message		;Display greeting
-			call	write_string
-			ld	hl,address_entry_msg	;get ready to get address
-			call	write_string
-			call	address_entry		;returns with address in HL
-			call	write_newline
-			call	memory_dump
-			jp	monitor_start
-;
-;Hex loader, displays formatted input
-load_jump:		ld	hl,load_message		;Display greeting
-			call	write_string		;get address to load
-			ld	hl,address_entry_msg	;get ready to get address
-			call	write_string
-			call	address_entry
-			call	write_newline
-			call	memory_load
-			jp	monitor_start
-;
-;Jump and run do the same thing: get an address and jump to it.
-run_jump:		ld	hl,run_message		;Display greeting
-			call	write_string
-			ld	hl,address_entry_msg	;get ready to get address
-			call	write_string
-			call	address_entry
-			jp	(hl)
-;
-;Help and ? do the same thing, display the available commands
-help_jump:		ld	hl,help_message
-			call	write_string
-			ld	bc,parse_table		;table with pointers to command strings
-help_loop:		ld	a,(bc)			;displays the strings for matching commands,
-			ld	l,a			;getting the string addresses from the
-			inc	bc			;parse table
-			ld	a,(bc)			;pass address of string to hl through a reg
-			ld	h,a
-			ld	a,(hl)			;hl now points to start of match string
-			or	000h			;exit if no_match string
-			jp	z,help_done
-			push	bc			;write_char uses b register
-			ld	a,020h			;space char
-			call	write_char
-			pop	bc
-			call	write_string		;writes match string
-			inc	bc			;pass over jump address in table
-			inc	bc
-			inc	bc
-			jp	help_loop
-help_done:		jp	monitor_start
-;
-;Binary file load. Need both address to load and length of file
-bload_jump:		ld	hl,bload_message
-			call	write_string
-			ld	hl,address_entry_msg
-			call	write_string
-			call	address_entry
-			call	write_newline
-			push	hl
-			ld	hl,length_entry_string
-			call	write_string
-			call	decimal_entry
-			ld	b,h
-			ld	c,l
-			ld	hl,bload_ready_message
-			call	write_string
-			pop	hl
-			call	bload
-			jp	monitor_start
-;
-;Binary memory dump. Need address of start of dump and no. bytes
-bdump_jump:		ld	hl,bdump_message
-			call	write_string
-			ld	hl,address_entry_msg
-			call	write_string
-			call	address_entry
-			call	write_newline
-			push	hl
-			ld	hl,dump_entry_string
-			call	write_string
-			call	decimal_entry
-			ld	b,h
-			ld	c,l
-			ld	hl,bdump_ready_message
-			call	write_string
-			call	get_char
-			pop	hl
-			call	bdump
-			jp	monitor_start
-;Disk read. Need memory address to place data, LBA of sector to read
-diskrd_jump:		ld	hl,diskrd_message
-			call	write_string
-			ld	hl,address_entry_msg
-			call	write_string
-			call	address_entry
-			call	write_newline
-			push	hl
-			ld	hl,LBA_entry_string
-			call	write_string
-			call	decimal_entry
-			ld	b,h
-			ld	c,l
-			ld	e,00h
-			pop	hl
-			call	disk_read
-			jp	monitor_start
-diskwr_jump:		ld	hl,diskwr_message
-			call	write_string
-			ld	hl,address_entry_msg
-			call	write_string
-			call	address_entry
-			call	write_newline
-			push	hl
-			ld	hl,LBA_entry_string
-			call	write_string
-			call	decimal_entry
-			ld	b,h
-			ld	c,l
-			ld	e,00h
-			pop	hl
-			call	disk_write
-			jp	monitor_start
-exit_jump:		jp	0000h			; Exit CP/M
-;Prints message for no match to entered command
-no_match_jump:		ld	hl,no_match_message
-			call	write_string
-			ld	hl, buffer
-			call	write_string
-			jp	monitor_start
-;
-;Monitor data structures:
-;
-monitor_message: 	defm	13,10,"ROM ver. 8",13,10,0
-no_match_message:	defm	"? ",0
-help_message:		defm	"Commands implemented:",13,10,0
-dump_message:		defm	"Displays a 256-byte block of memory.",13,10,0
-load_message:		defm	"Enter hex bytes starting at memory location.",13,10,0
-run_message:		defm	"Will jump to (execute) program at address entered.",13,10,0
-bload_message:		defm	"Loads a binary file into memory.",13,10,0
-bload_ready_message:	defm	13,10,"Ready to receive, start transfer.",0
-bdump_message:		defm	"Dumps binary data from memory to serial port.",13,10,0
-bdump_ready_message:	defm	13,10,"Ready to send, hit any key to start.",0
-diskrd_message:		defm	"Reads one sector from disk to memory.",13,10,0
-diskwr_message:		defm	"Writes one sector from memory to disk.",13,10,0
-;Strings for matching:
-dump_string:		defm	"dump",0
-load_string:		defm	"load",0
-jump_string:		defm	"jump",0
-run_string:		defm	"run",0
-question_string:	defm	"?",0
-help_string:		defm	"help",0
-bload_string:		defm	"bload",0
-bdump_string:		defm	"bdump",0
-diskrd_string:		defm	"diskrd",0
-diskwr_string:		defm	"diskwr",0
-exit_string:		defm	"exit",0
-no_match_string:	defm	0,0
-;Table for matching strings to jumps
-parse_table:		defw	dump_string,dump_jump,load_string,load_jump
-			defw	jump_string,run_jump,run_string,run_jump
-			defw	question_string,help_jump,help_string,help_jump
-			defw	bload_string,bload_jump,bdump_string,bdump_jump
-			defw	diskrd_string,diskrd_jump,diskwr_string,diskwr_jump
-			defw	exit_string,exit_jump
-			defw	no_match_string,no_match_jump
-code_end:
-			end
-
-
diff --git a/src/loader.z80 b/src/loader.z80
deleted file mode 100644
index acbb2ed..0000000
--- a/src/loader.z80
+++ /dev/null
@@ -1,30 +0,0 @@
-;Retrieves CP/M from disk and loads it in memory starting at E400h
-;Uses calls to ROM subroutine for disk read.
-;Reads track 0, sectors 2 to 26, then track 1, sectors 1 to 25
-;This program is loaded into LBA sector 0 of disk, read to loc. 0800h by ROM disk_read subroutine, and executed.
-
-#target bin
-#code _HOME, 0x1100
-
-hstbuf    equ 0x1200         ;will put 256-byte raw sector here
-disk_read equ 0x0296         ;subroutine in 2K ROM
-cpm       equ 0xFA00         ;CP/M cold start entry in BIOS
-
-main:
-	ld c,1                   ;LBA bits 0 to 7
-	ld b,0                   ;LBA bits 8 to 15
-	ld e,0                   ;LBA bits 16 to 23
-	ld hl,0xE400             ; Memory address -- start of CCP
-
-loop:
-	call disk_read           ;subroutine in ROM
-	ld a,c
-	cp 50
-	jp z,done
-	inc a
-	ld c,a
-	jp loop
-
-done:
-	out (1),a                ;switch memory config to all-RAM
-	jp cpm                   ;to BIOS cold start entry
diff --git a/src/putsys.z80 b/src/putsys.z80
deleted file mode 100644
index de68318..0000000
--- a/src/putsys.z80
+++ /dev/null
@@ -1,56 +0,0 @@
-;Copies the memory image of CP/M loaded at E400h onto tracks 0 and 1 of the first CP/M disk
-;Load and run from ROM monitor
-;Uses calls to BIOS, in memory at FA00h
-;Writes track 0, sectors 2 to 26, then track 1, sectors 1 to 25
-
-#target bin
-#code _HOME, 0x1400
-
-_bios  equ (0x4A00+0xB000)
-seldsk equ _bios+0x1b
-settrk equ _bios+0x1e
-setsec equ _bios+0x21
-setdma equ _bios+0x24
-write  equ _bios+0x2a
-
-monitor_warm_start equ 0x0433      ;Return to ROM monitor
-
-main:
-    ld c,00h                       ;CP/M disk a
-    call seldsk
-
-;Write track 0, sectors 2 to 51
-    ld a,1                         ;starting sector
-    ld (sector),a
-    ld hl, 0x6400                  ;start of CCP
-    ld (address),hl
-    ld c,0                         ;CP/M track
-    call settrk
-
-wr_trk_0_loop:
-    ld a,(sector)
-    ld c,a                         ;CP/M sector
-    call setsec
-    ld bc,(address)                ;memory location
-    call setdma
-    call write
-    ld a,(sector)
-    cp 50                          ;done:
-    jp z,done                      ;yes
-    inc a                          ;no, next sector
-    ld (sector),a
-    ld hl,(address)
-    ld de,128
-    add hl,de
-    ld (address),hl
-    jp wr_trk_0_loop
-
-done:
-    jp 0x0000
-
-sector:
-    db 00h
-
-address:
-    dw 0000h
-    end
diff --git a/src/ram_monitor.z80 b/src/ram_monitor.z80
deleted file mode 100644
index c07a671..0000000
--- a/src/ram_monitor.z80
+++ /dev/null
@@ -1,687 +0,0 @@
-;RAM monitor for a system with serial interface and IDE disk and memory expansion board.
-;This program to be loaded at DC00h by ROM monitor, and run from there.
-;Assumes serial port has been initialized by ROM monitor.
-;Assumes the UART data port address is 02h and control/status address is 03h
-;
-;The subroutines use these variables in RAM, same area as ROM monitor:
-current_location:	equ	0x1300		;word variable in RAM
-line_count:		equ	0x1302		;byte variable in RAM
-byte_count:		equ	0x1303		;byte variable in RAM
-value_pointer:		equ	0x1304		;word variable in RAM
-current_value:		equ	0x1306		;word variable in RAM
-buffer:			equ	0x1308		;buffer in RAM -- up to stack area
-;Can use same stack as ROM monitor. Stack not re-initialized, listed here for information
-;ROM_monitor_stack:	equ	0x13ff		;upper TPA in RAM, below RAM monitor
-;
-;
-			org	01400h
-			out	(1),a			;change memory configuration to all-RAM
-			jp 	monitor_start			
-;
-;Puts a single char (byte value) on serial output
-;Call with char to send in A register. Uses B register
-write_char:		ld	b,a			;store char
-write_char_loop:	in	a,(3)			;check if OK to send
-			and	001h			;check TxRDY bit
-			jp 	z,write_char_loop	;loop if not set
-			ld 	a,b			;get char back
-			out 	(2),a			;send to output
-			ret				;returns with char in a
-;
-;Subroutine to write a zero-terminated string to serial output
-;Pass address of string in HL register
-;No error checking
-write_string:		in 	a,(3)			;read status
-			and 	001h			;check TxRDY bit
-			jp 	z,write_string		;loop if not set
-			ld 	a,(hl)			;get char from string
-			and 	a			;check if 0
-			ret 	z			;yes, finished
-			out 	(2),a			;no, write char to output
-			inc 	hl			;next char in string
-			jp 	write_string		;start over
-;
-;Binary loader. Receive a binary file, place in memory.
-;Address of load passed in HL, length of load (= file length) in BC
-bload:			in 	a,(0x1F)			;get status
-			and 	001h			;check RxRDY bit
-			jp 	z,bload			;not ready, loop
-			in	a,(0x1E)
-			ld	(hl),a
-			inc	hl
-			dec	bc			;byte counter
-			ld	a,b			;need to test BC this way because
-			or	c			;dec rp instruction does not change flags
-			jp	nz,bload
-			ret
-;
-;Binary dump to port. Send a stream of binary data from memory to serial output
-;Address of dump passed in HL, length of dump in BC
-bdump:			in 	a,(3)			;get status
-			and 	001h			;check TxRDY bit
-			jp 	z,bdump			;not ready, loop
-			ld	a,(hl)
-			out	(2),a
-			inc	hl
-			dec	bc
-			ld	a,b			;need to test this way because
-			or	c			;dec rp instruction does not change flags
-			jp	nz,bdump
-			ret
-;
-;Subroutine to get a string from serial input, place in buffer.
-;Buffer address passed in HL reg.
-;Uses A,BC,DE,HL registers (including calls to other subroutines).
-;Line entry ends by hitting return key. Return char not included in string (replaced by zero).
-;Backspace editing OK. No error checking.
-;
-get_line:		ld	c,000h			;line position
-			ld	a,h			;put original buffer address in de
-			ld	d,a			;after this don't need to preserve hl
-			ld	a,l			;subroutines called don't use de
-			ld	e,a
-get_line_next_char:	in 	a,(0x1F)			;get status
-			and 	001h			;check RxRDY bit
-			jp 	z,get_line_next_char	;not ready, loop
-			in 	a,(0x1E)			;get char
-			cp	00dh			;check if return
-			ret	z			;yes, normal exit
-			cp	07fh			;check if backspace (VT102 keys)
-			jp	z,get_line_backspace	;yes, jump to backspace routine
-			cp	008h			;check if backspace (ANSI keys)
-			jp	z,get_line_backspace	;yes, jump to backspace
-			call	write_char		;put char on screen
-			ld	(de),a			;store char in buffer
-			inc	de			;point to next space in buffer
-			inc	c			;inc counter
-			ld	a,000h
-			ld	(de),a			;leaves a zero-terminated string in buffer
-			jp	get_line_next_char
-get_line_backspace:	ld	a,c			;check current position in line
-			cp	000h			;at beginning of line?
-			jp	z,get_line_next_char	;yes, ignore backspace, get next char
-			dec	de			;no, erase char from buffer
-			dec	c			;back up one
-			ld	a,000h			;put a zero in buffer where the last char was
-			ld	(de),a
-			ld	hl,erase_char_string	;ANSI sequence to delete one char from line
-			call	write_string		;transmits sequence to backspace and erase char
-			jp	get_line_next_char
-;
-;Creates a two-char hex string from the byte value passed in register A
-;Location to place string passed in HL
-;String is zero-terminated, stored in 3 locations starting at HL
-;Also uses registers b,d, and e
-byte_to_hex_string:	ld	b,a			;store original byte
-			srl	a			;shift right 4 times, putting
-			srl	a			;high nybble in low-nybble spot
-			srl	a			;and zeros in high-nybble spot
-			srl	a
-			ld	d,000h			;prepare for 16-bit addition
-			ld	e,a			;de contains offset
-			push	hl			;temporarily store string target address
-			ld	hl,hex_char_table	;use char table to get high-nybble character
-			add	hl,de			;add offset to start of table
-			ld	a,(hl)			;get char
-			pop	hl			;get string target address
-			ld	(hl),a			;store first char of string
-			inc	hl			;point to next string target address
-			ld	a,b			;get original byte back from reg b
-			and	00fh			;mask off high-nybble
-			ld	e,a			;d still has 000h, now de has offset
-			push	hl			;temp store string target address
-			ld	hl,hex_char_table	;start of table
-			add	hl,de			;add offset
-			ld	a,(hl)			;get char
-			pop	hl			;get string target address
-			ld	(hl),a			;store second char of string
-			inc	hl			;point to third location
-			ld	a,000h			;zero to terminate string
-			ld	(hl),a			;store the zero
-			ret				;done
-;
-;Converts a single ASCII hex char to a nybble value
-;Pass char in reg A. Letter numerals must be upper case.
-;Return nybble value in low-order reg A with zeros in high-order nybble if no error.
-;Return 0ffh in reg A if error (char not a valid hex numeral).
-;Also uses b, c, and hl registers.
-hex_char_to_nybble:	ld	hl,hex_char_table
-			ld	b,00fh			;no. of valid characters in table - 1.
-			ld	c,000h			;will be nybble value
-hex_to_nybble_loop:	cp	(hl)			;character match here?
-			jp	z,hex_to_nybble_ok	;match found, exit
-			dec	b			;no match, check if at end of table
-			jp	m,hex_to_nybble_err	;table limit exceded, exit with error
-			inc	c			;still inside table, continue search
-			inc	hl
-			jp	hex_to_nybble_loop
-hex_to_nybble_ok:	ld	a,c			;put nybble value in a
-			ret
-hex_to_nybble_err:	ld	a,0ffh			;error value
-			ret
-;
-;Converts a hex character pair to a byte value
-;Called with location of high-order char in HL
-;If no error carry flag clear, returns with byte value in register A, and
-;HL pointing to next mem location after char pair.
-;If error (non-hex char) carry flag set, HL pointing to invalid char
-hex_to_byte:		ld	a,(hl)			;location of character pair
-			push	hl			;store hl (hex_char_to_nybble uses it)
-			call	hex_char_to_nybble
-			pop	hl			;returns with nybble value in a reg, or 0ffh if error
-			cp	0ffh			;non-hex character?
-			jp	z,hex_to_byte_err	;yes, exit with error
-			sla	a			;no, move low order nybble to high side
-			sla	a
-			sla	a
-			sla	a
-			ld	d,a			;store high-nybble
-			inc	hl			;get next character of the pair
-			ld	a,(hl)
-			push	hl			;store hl
-			call	hex_char_to_nybble
-			pop	hl
-			cp	0ffh			;non-hex character?
-			jp	z,hex_to_byte_err	;yes, exit with error
-			or	d			;no, combine with high-nybble
-			inc	hl			;point to next memory location after char pair
-			scf
-			ccf				;no-error exit (carry = 0)
-			ret
-hex_to_byte_err:	scf				;error, carry flag set
-			ret
-hex_char_table:		defm	"0123456789ABCDEF"	;ASCII hex table
-;
-;Subroutine to get a two-byte address from serial input.
-;Returns with address value in HL
-;Uses locations in RAM for buffer and variables
-address_entry:		ld	hl,buffer		;location for entered string
-			call	get_line		;returns with address string in buffer
-			ld	hl,buffer		;location of stored address entry string
-			call	hex_to_byte		;will get high-order byte first
-			jp	c, address_entry_error	;if error, jump
-			ld	(current_location+1),a	;store high-order byte, little-endian
-			ld	hl,buffer+2		;point to low-order hex char pair
-			call	hex_to_byte		;get low-order byte
-			jp	c, address_entry_error	;jump if error
-			ld	(current_location),a	;store low-order byte in lower memory
-			ld	hl,(current_location)	;put memory address in hl
-			ret
-address_entry_error:	ld	hl,address_error_msg
-			call	write_string
-			jp	address_entry
-;
-;Subroutine to get a decimal string, return a word value
-;Calls decimal_string_to_word subroutine
-decimal_entry:		ld	hl,buffer
-			call	get_line		;returns with DE pointing to terminating zero
-			ld	hl,buffer
-			call	decimal_string_to_word
-			ret	nc			;no error, return with word in hl
-			ld	hl,decimal_error_msg	;error, try again
-			call	write_string
-			jp	decimal_entry
-;
-;Subroutine to convert a decimal string to a word value
-;Call with address of string in HL, pointer to end of string in DE
-;Carry flag set if error (non-decimal char)
-;Carry flag clear, word value in HL if no error.
-decimal_string_to_word:	ld	b,d
-			ld	c,e			;use BC as string pointer
-			ld	(current_location),hl	;store addr. of start of buffer in RAM word variable
-			ld	hl,000h			;starting value zero
-			ld	(current_value),hl
-			ld	hl,decimal_place_value	;pointer to values
-			ld	(value_pointer),hl
-decimal_next_char:	dec	bc			;next char in string (moving right to left)
-			ld	hl,(current_location)	;check if at end of decimal string
-			scf				;get ready to subtract de from buffer addr.
-			ccf				;set carry to zero (clear)
-			sbc	hl,bc			;keep going if bc > or = hl (buffer address)
-			jp	c,decimal_continue	;borrow means bc > hl
-			jp	z,decimal_continue	;z means bc = hl
-			ld	hl,(current_value)	;return if de < buffer address (no borrow)
-			scf				;get value back from RAM variable
-			ccf
-			ret				;return with carry clear, value in hl
-decimal_continue:	ld	a,(bc)			;next char in string (right to left)
-			sub	030h			;ASCII value of zero char
-			jp	m,decimal_error		;error if char value less than 030h
-			cp	00ah			;error if byte value > or = 10 decimal
-			jp	p,decimal_error		;a reg now has value of decimal numeral
-			ld	hl,(value_pointer)	;get value to add an put in de
-			ld	e,(hl)			;little-endian (low byte in low memory)
-			inc	hl
-			ld	d,(hl)
-			inc	hl			;hl now points to next value
-			ld	(value_pointer),hl
-			ld	hl,(current_value)	;get back current value
-decimal_add:		dec	a			;add loop to increase total value
-			jp	m,decimal_add_done	;end of multiplication
-			add	hl,de
-			jp	decimal_add
-decimal_add_done:	ld	(current_value),hl
-			jp	decimal_next_char
-decimal_error:		scf
-			ret
-			jp	decimal_add
-decimal_place_value:	defw	1,10,100,1000,10000
-;
-;Memory dump
-;Displays a 256-byte block of memory in 16-byte rows.
-;Called with address of start of block in HL
-memory_dump:		ld	(current_location),hl	;store address of block to be displayed
-			ld	a,000h
-			ld	(byte_count),a		;initialize byte count
-			ld	(line_count),a		;initialize line count
-			jp	dump_new_line
-dump_next_byte:		ld	hl,(current_location)	;get byte address from storage,
-			ld	a,(hl)			;get byte to be converted to string
-			inc	hl			;increment address and
-			ld	(current_location),hl	;store back
-			ld	hl,buffer		;location to store string
-			call	byte_to_hex_string	;convert
-			ld	hl,buffer		;display string
-			call	write_string
-			ld	a,(byte_count)		;next byte
-			inc	a
-			jp	z,dump_done		;stop when 256 bytes displayed
-			ld	(byte_count),a		;not finished yet, store
-			ld	a,(line_count)		;end of line (16 characters)?
-			cp	00fh			;yes, start new line
-			jp	z,dump_new_line
-			inc	a			;no, increment line count
-			ld	(line_count),a
-			ld	a,020h			;print space
-			call	write_char
-			jp	dump_next_byte		;continue
-dump_new_line:		ld	a,000h			;reset line count to zero
-			ld	(line_count),a			
-			call	write_newline
-			ld	hl,(current_location)	;location of start of line
-			ld	a,h			;high byte of address
-			ld	hl, buffer
-			call	byte_to_hex_string	;convert
-			ld	hl,buffer
-			call	write_string		;write high byte
-			ld	hl,(current_location)
-			ld	a,l			;low byte of address
-			ld	hl, buffer
-			call	byte_to_hex_string	;convert
-			ld	hl,buffer
-			call	write_string		;write low byte
-			ld	a,020h			;space
-			call	write_char
-			jp	dump_next_byte		;now write 16 bytes
-dump_done:		ld	a,000h
-			ld	hl,buffer
-			ld	(hl),a			;clear buffer of last string
-			call	write_newline
-			ret
-;
-;Memory load
-;Loads RAM memory with bytes entered as hex characters
-;Called with address to start loading in HL
-;Displays entered data in 16-byte rows.
-memory_load:		ld	(current_location),hl
-			ld	hl,data_entry_msg
-			call	write_string
-			jp	load_new_line
-load_next_char:		call	get_char
-			cp	00dh			;return?
-			jp	z,load_done		;yes, quit
-			ld	(buffer),a
-			call	get_char
-			cp	00dh			;return?
-			jp	z,load_done		;yes, quit
-			ld	(buffer+1),a
-			ld	hl,buffer
-			call	hex_to_byte
-			jp	c,load_data_entry_error	;non-hex character
-			ld	hl,(current_location)	;get byte address from storage,
-			ld	(hl),a			;store byte
-			inc	hl			;increment address and
-			ld	(current_location),hl	;store back
-			ld	a,(buffer)
-			call	write_char
-			ld	a,(buffer+1)
-			call	write_char
-			ld	a,(line_count)		;end of line (16 characters)?
-			cp	00fh			;yes, start new line
-			jp	z,load_new_line
-			inc	a			;no, increment line count
-			ld	(line_count),a
-			ld	a,020h			;print space
-			call	write_char
-			jp	load_next_char		;continue
-load_new_line:		ld	a,000h			;reset line count to zero
-			ld	(line_count),a
-			call	write_newline
-			jp	load_next_char		;continue
-load_data_entry_error:	call	write_newline
-			ld	hl,data_error_msg
-			call	write_string
-			ret
-load_done:		call	write_newline
-			ret
-;
-;Get one ASCII character from the serial port.
-;Returns with char in A reg. No error checking.
-get_char:		in 	a,(0x1F)			;get status
-			and 	001h			;check RxRDY bit
-			jp 	z,get_char		;not ready, loop
-			in 	a,(0x1E)			;get char
-			ret
-;
-;Subroutine to start a new line
-write_newline:		ld	a,00dh			;ASCII carriage return character
-			call	write_char
-			ld	a,00ah			;new line (line feed) character
-			call	write_char
-			ret
-;
-;Subroutine to read one disk sector (128 bytes)
-;Address to place data passed in HL
-;LBA bits 0 to 7 passed in C, bits 8 to 15 passed in B
-;LBA bits 16 to 23 passed in E
-disk_read:
-rd_status_loop_1:	in	a,(0fh)		;check status
-			and	80h		;check BSY bit
-			jp	nz,rd_status_loop_1	;loop until not busy
-rd_status_loop_2:	in	a,(0fh)		;check	status
-			and	40h		;check DRDY bit
-			jp	z,rd_status_loop_2	;loop until ready
-			ld	a,01h		;number of sectors = 1
-			out	(0ah),a		;sector count register
-			ld	a,c
-			out	(0bh),a		;lba bits 0 - 7
-			ld	a,b
-			out	(0ch),a		;lba bits 8 - 15
-			ld	a,e
-			out	(0dh),a		;lba bits 16 - 23
-			ld	a,11100000b	;LBA mode, select drive 0
-			out	(0eh),a		;drive/head register
-			ld	a,20h		;Read sector command
-			out	(0fh),a
-rd_wait_for_DRQ_set:	in	a,(0fh)		;read status
-			and	08h		;DRQ bit
-			jp	z,rd_wait_for_DRQ_set	;loop until bit set
-rd_wait_for_BSY_clear:	in	a,(0fh)
-			and	80h
-			jp	nz,rd_wait_for_BSY_clear
-			in	a,(0fh)		;clear INTRQ
-read_loop:		in	a,(08h)		;get data
-			ld	(hl),a
-			inc	hl
-			in	a,(0fh)		;check status
-			and	08h		;DRQ bit
-			jp	nz,read_loop	;loop until cleared
-			ret
-;
-;Subroutine to write one disk sector (128 bytes)
-;Address of data to write to disk passed in HL
-;LBA bits 0 to 7 passed in C, bits 8 to 15 passed in B
-;LBA bits 16 to 23 passed in E
-disk_write:
-wr_status_loop_1:	in	a,(0fh)		;check status
-			and	80h		;check BSY bit
-			jp	nz,wr_status_loop_1	;loop until not busy
-wr_status_loop_2:	in	a,(0fh)		;check	status
-			and	40h		;check DRDY bit
-			jp	z,wr_status_loop_2	;loop until ready
-			ld	a,01h		;number of sectors = 1
-			out	(0ah),a		;sector count register
-			ld	a,c
-			out	(0bh),a		;lba bits 0 - 7
-			ld	a,b
-			out	(0ch),a		;lba bits 8 - 15
-			ld	a,e
-			out	(0dh),a		;lba bits 16 - 23
-			ld	a,11100000b	;LBA mode, select drive 0
-			out	(0eh),a		;drive/head register
-			ld	a,30h		;Write sector command
-			out	(0fh),a
-wr_wait_for_DRQ_set:	in	a,(0fh)		;read status
-			and	08h		;DRQ bit
-			jp	z,wr_wait_for_DRQ_set	;loop until bit set			
-write_loop:		ld	a,(hl)
-			out	(08h),a		;write data
-			inc	hl
-			in	a,(0fh)		;read status
-			and	08h		;check DRQ bit
-			jp	nz,write_loop	;write until bit cleared
-wr_wait_for_BSY_clear:	in	a,(0fh)
-			and	80h
-			jp	nz,wr_wait_for_BSY_clear
-			in	a,(0fh)		;clear INTRQ
-			ret
-;
-;Strings used in subroutines
-length_entry_string:	defm	"Enter length of file to load (decimal): ",0
-dump_entry_string:	defm	"Enter no. of bytes to dump (decimal): ",0
-LBA_entry_string:	defm	"Enter LBA (decimal, 0 to 65535): ",0
-erase_char_string:	defm	008h,01bh,"[K",000h	;ANSI sequence for backspace, erase to end of line.
-address_entry_msg:	defm	"Enter 4-digit hex address (use upper-case A through F): ",0
-address_error_msg:	defm	13,10,"Error: invalid hex character, try again: ",0
-data_entry_msg:		defm	"Enter hex bytes, hit return when finished.",13,10,0
-data_error_msg:		defm	"Error: invalid hex byte.",13,10,0
-decimal_error_msg:	defm	13,10,"Error: invalid decimal number, try again: ",0
-;
-;Simple monitor program for CPUville Z80 computer with serial interface.
-
-monitor_start:		call	write_newline		;routine program return here to avoid re-initialization of port
-			ld	a,03eh			;cursor symbol
-			call	write_char
-			ld	hl,buffer
-			call	get_line		;get monitor input string (command)
-			call	write_newline
-			call	parse			;interprets command, returns with address to jump to in HL
-			jp	(hl)
-;
-;Parses an input line stored in buffer for available commands as described in parse table.
-;Returns with address of jump to action for the command in HL
-parse:			ld	bc,parse_table		;bc is pointer to parse_table
-parse_start:		ld	a,(bc)			;get pointer to match string from parse table
-			ld	e,a
-			inc	bc
-			ld	a,(bc)			
-			ld	d,a			;de will is pointer to strings for matching
-			ld	a,(de)			;get first char from match string
-			or	000h			;zero?
-			jp	z,parser_exit		;yes, exit no_match
-			ld	hl,buffer		;no, parse input string 
-match_loop:		cp	(hl)			;compare buffer char with match string char
-			jp	nz,no_match		;no match, go to next match string
-			or	000h			;end of strings (zero)?
-			jp	z,parser_exit		;yes, matching string found
-			inc	de			;match so far, point to next char in match string
-			ld	a,(de)			;get next character from match string
-			inc	hl			;and point to next char in input string
-			jp	match_loop		;check for match
-no_match:		inc	bc			;skip over jump target to
-			inc	bc
-			inc	bc			;get address of next matching string
-			jp	parse_start
-parser_exit:		inc	bc			;skip to address of jump for match
-			ld	a,(bc)
-			ld	l,a
-			inc	bc
-			ld	a,(bc)
-			ld	h,a			;returns with jump address in hl
-			ret
-;
-;Actions to be taken on match
-;
-;Memory dump program
-;Input 4-digit hexadecimal address
-;Calls memory_dump subroutine
-dump_jump:		ld	hl,dump_message		;Display greeting
-			call	write_string
-			ld	hl,address_entry_msg	;get ready to get address
-			call	write_string
-			call	address_entry		;returns with address in HL
-			call	write_newline
-			call	memory_dump
-			jp	monitor_start
-;
-;Hex loader, displays formatted input
-load_jump:		ld	hl,load_message		;Display greeting
-			call	write_string		;get address to load
-			ld	hl,address_entry_msg	;get ready to get address
-			call	write_string
-			call	address_entry
-			call	write_newline
-			call	memory_load
-			jp	monitor_start
-;
-;Jump and run do the same thing: get an address and jump to it.
-run_jump:		ld	hl,run_message		;Display greeting
-			call	write_string
-			ld	hl,address_entry_msg	;get ready to get address
-			call	write_string
-			call	address_entry
-			jp	(hl)
-;
-;Help and ? do the same thing, display the available commands
-help_jump:		ld	hl,help_message
-			call	write_string
-			ld	bc,parse_table		;table with pointers to command strings
-help_loop:		ld	a,(bc)			;displays the strings for matching commands,
-			ld	l,a			;getting the string addresses from the
-			inc	bc			;parse table
-			ld	a,(bc)			;pass address of string to hl through a reg
-			ld	h,a
-			ld	a,(hl)			;hl now points to start of match string
-			or	000h			;exit if no_match string
-			jp	z,help_done
-			push	bc			;write_char uses b register
-			ld	a,020h			;space char
-			call	write_char
-			pop	bc
-			call	write_string		;writes match string
-			inc	bc			;pass over jump address in table
-			inc	bc
-			inc	bc
-			jp	help_loop
-help_done:		jp	monitor_start
-;
-;Binary file load. Need both address to load and length of file
-bload_jump:		ld	hl,bload_message
-			call	write_string
-			ld	hl,address_entry_msg
-			call	write_string
-			call	address_entry
-			call	write_newline
-			push	hl
-			ld	hl,length_entry_string
-			call	write_string
-			call	decimal_entry
-			ld	b,h
-			ld	c,l
-			ld	hl,bload_ready_message
-			call	write_string
-			pop	hl
-			call	bload
-			jp	monitor_start
-;
-;Binary memory dump. Need address of start of dump and no. bytes
-bdump_jump:		ld	hl,bdump_message
-			call	write_string
-			ld	hl,address_entry_msg
-			call	write_string
-			call	address_entry
-			call	write_newline
-			push	hl
-			ld	hl,dump_entry_string
-			call	write_string
-			call	decimal_entry
-			ld	b,h
-			ld	c,l
-			ld	hl,bdump_ready_message
-			call	write_string
-			call	get_char
-			pop	hl
-			call	bdump
-			jp	monitor_start
-;Disk read. Need memory address to place data, LBA of sector to read
-diskrd_jump:		ld	hl,diskrd_message
-			call	write_string
-			ld	hl,address_entry_msg
-			call	write_string
-			call	address_entry
-			call	write_newline
-			push	hl
-			ld	hl,LBA_entry_string
-			call	write_string
-			call	decimal_entry
-			ld	b,h
-			ld	c,l
-			ld	e,00h
-			pop	hl
-			call	disk_read
-			jp	monitor_start
-diskwr_jump:		ld	hl,diskwr_message
-			call	write_string
-			ld	hl,address_entry_msg
-			call	write_string
-			call	address_entry
-			call	write_newline
-			push	hl
-			ld	hl,LBA_entry_string
-			call	write_string
-			call	decimal_entry
-			ld	b,h
-			ld	c,l
-			ld	e,00h
-			pop	hl
-			call	disk_write
-			jp	monitor_start
-boot_jump:		ld	hl,1100h
-			ld	bc,0000h
-			ld	e,00h
-			call	disk_read
-			out	(0),a			;CP/M loader uses ROM routine to read disk
-			jp	1100h
-;Prints message for no match to entered command
-no_match_jump:		ld	hl,no_match_message
-			call	write_string
-			ld	hl, buffer
-			call	write_string
-			jp	monitor_start
-;
-;Monitor data structures:
-;
-monitor_message: 	defm	13,10,"ROM ver. 8",13,10,0
-no_match_message:	defm	"? ",0
-help_message:		defm	"Commands implemented:",13,10,0
-dump_message:		defm	"Displays a 256-byte block of memory.",13,10,0
-load_message:		defm	"Enter hex bytes starting at memory location.",13,10,0
-run_message:		defm	"Will jump to (execute) program at address entered.",13,10,0
-bload_message:		defm	"Loads a binary file into memory.",13,10,0
-bload_ready_message:	defm	13,10,"Ready to receive, start transfer.",0
-bdump_message:		defm	"Dumps binary data from memory to serial port.",13,10,0
-bdump_ready_message:	defm	13,10,"Ready to send, hit any key to start.",0
-diskrd_message:		defm	"Reads one sector from disk to memory.",13,10,0
-diskwr_message:		defm	"Writes one sector from memory to disk.",13,10,0
-;Strings for matching:
-dump_string:		defm	"dump",0
-load_string:		defm	"load",0
-jump_string:		defm	"jump",0
-run_string:		defm	"run",0
-question_string:	defm	"?",0
-help_string:		defm	"help",0
-bload_string:		defm	"bload",0
-bdump_string:		defm	"bdump",0
-diskrd_string:		defm	"diskrd",0
-diskwr_string:		defm	"diskwr",0
-boot_string:		defm	"boot",0
-no_match_string:	defm	0,0
-;Table for matching strings to jumps
-parse_table:		defw	dump_string,dump_jump,load_string,load_jump
-			defw	jump_string,run_jump,run_string,run_jump
-			defw	question_string,help_jump,help_string,help_jump
-			defw	bload_string,bload_jump,bdump_string,bdump_jump
-			defw	diskrd_string,diskrd_jump,diskwr_string,diskwr_jump
-			defw	boot_string,boot_jump
-			defw	no_match_string,no_match_jump
-
diff --git a/src/rom_monitor.z80 b/src/rom_monitor.z80
deleted file mode 100644
index 3f8ac2b..0000000
--- a/src/rom_monitor.z80
+++ /dev/null
@@ -1,675 +0,0 @@
-;ROM monitor for a system with serial interface and IDE disk and memory expansion board.
-;The disk extension board has 64K RAM -- computer board memory decoder disabled (J2 off).
-;The disk extension board uses ports 2 and 3 for the serial interface, and 8 to 15 for the disk
-;Therefore the computer board I/O decoder is also disabled (J1 off)
-;Output to port 0 will cause memory configuration flip-flop to activate 2K ROM 0000-07FF with 62K RAM 0800-FFFF
-;Output to port 1 will cause memory configuration flip-flop to activate all RAM 0000-FFFF
-;
-			org	00000h
-			jp 	monitor_cold_start			
-;
-;The following code is for a system with a serial port.
-;Assumes the UART data port address is 02h and control/status address is 03h
-;
-;The subroutines for the serial port use these variables in RAM:
-current_location:	equ	0x1000		;word variable in RAM
-line_count:		equ	0x1002		;byte variable in RAM
-byte_count:		equ	0x1003		;byte variable in RAM
-value_pointer:		equ	0x1004		;word variable in RAM
-current_value:		equ	0x1006		;word variable in RAM
-buffer:			equ	0x1008		;buffer in RAM -- up to stack area
-;Need to have stack in upper RAM, but not in area of CP/M or RAM monitor.
-ROM_monitor_stack:	equ	0x10ff		;upper TPA in RAM, below RAM monitor
-;
-;Subroutine to initialize serial port UART
-;Needs to be called only once after computer comes out of reset.
-;If called while port is active will cause port to fail.
-;16x = 9600 baud
-initialize_port:	ld 	a,04eh			;1 stop bit, no parity, 8-bit char, 16x baud
-			out 	(3),a			;write to control port
-			ld 	a,037h			;enable receive and transmit
-			out 	(3),a			;write to control port
-			out 	(3),a			;write to control port
-			ret
-;
-;Puts a single char (byte value) on serial output
-;Call with char to send in A register. Uses B register
-write_char:		ld	b,a			;store char
-write_char_loop:	in	a,(3)			;check if OK to send
-			and	001h			;check TxRDY bit
-			jp 	z,write_char_loop	;loop if not set
-			ld 	a,b			;get char back
-			out 	(2),a			;send to output
-			ret				;returns with char in a
-;
-;Subroutine to write a zero-terminated string to serial output
-;Pass address of string in HL register
-;No error checking
-write_string:		in 	a,(3)			;read status
-			and 	001h			;check TxRDY bit
-			jp 	z,write_string		;loop if not set
-			ld 	a,(hl)			;get char from string
-			and 	a			;check if 0
-			ret 	z			;yes, finished
-			out 	(2),a			;no, write char to output
-			inc 	hl			;next char in string
-			jp 	write_string		;start over
-;
-;Binary loader. Receive a binary file, place in memory.
-;Address of load passed in HL, length of load (= file length) in BC
-bload:			in 	a,(0x1F)			;get status
-			and 	001h			;check RxRDY bit
-			jp 	z,bload			;not ready, loop
-			in	a,(0x1E)
-			ld	(hl),a
-			inc	hl
-			dec	bc			;byte counter
-			ld	a,b			;need to test BC this way because
-			or	c			;dec rp instruction does not change flags
-			jp	nz,bload
-			ret
-;
-;Binary dump to port. Send a stream of binary data from memory to serial output
-;Address of dump passed in HL, length of dump in BC
-bdump:			in 	a,(3)			;get status
-			and 	001h			;check TxRDY bit
-			jp 	z,bdump			;not ready, loop
-			ld	a,(hl)
-			out	(2),a
-			inc	hl
-			dec	bc
-			ld	a,b			;need to test this way because
-			or	c			;dec rp instruction does not change flags
-			jp	nz,bdump
-			ret
-;
-;Subroutine to get a string from serial input, place in buffer.
-;Buffer address passed in HL reg.
-;Uses A,BC,DE,HL registers (including calls to other subroutines).
-;Line entry ends by hitting return key. Return char not included in string (replaced by zero).
-;Backspace editing OK. No error checking.
-;
-get_line:		ld	c,000h			;line position
-			ld	a,h			;put original buffer address in de
-			ld	d,a			;after this don't need to preserve hl
-			ld	a,l			;subroutines called don't use de
-			ld	e,a
-get_line_next_char:	in 	a,(0x1F)			;get status
-			and 	001h			;check RxRDY bit
-			jp 	z,get_line_next_char	;not ready, loop
-			in 	a,(0x1E)			;get char
-			cp	00dh			;check if return
-			ret	z			;yes, normal exit
-			cp	07fh			;check if backspace (VT102 keys)
-			jp	z,get_line_backspace	;yes, jump to backspace routine
-			cp	008h			;check if backspace (ANSI keys)
-			jp	z,get_line_backspace	;yes, jump to backspace
-			call	write_char		;put char on screen
-			ld	(de),a			;store char in buffer
-			inc	de			;point to next space in buffer
-			inc	c			;inc counter
-			ld	a,000h
-			ld	(de),a			;leaves a zero-terminated string in buffer
-			jp	get_line_next_char
-get_line_backspace:	ld	a,c			;check current position in line
-			cp	000h			;at beginning of line?
-			jp	z,get_line_next_char	;yes, ignore backspace, get next char
-			dec	de			;no, erase char from buffer
-			dec	c			;back up one
-			ld	a,000h			;put a zero in buffer where the last char was
-			ld	(de),a
-			ld	hl,erase_char_string	;ANSI sequence to delete one char from line
-			call	write_string		;transmits sequence to backspace and erase char
-			jp	get_line_next_char
-;
-;Creates a two-char hex string from the byte value passed in register A
-;Location to place string passed in HL
-;String is zero-terminated, stored in 3 locations starting at HL
-;Also uses registers b,d, and e
-byte_to_hex_string:	ld	b,a			;store original byte
-			srl	a			;shift right 4 times, putting
-			srl	a			;high nybble in low-nybble spot
-			srl	a			;and zeros in high-nybble spot
-			srl	a
-			ld	d,000h			;prepare for 16-bit addition
-			ld	e,a			;de contains offset
-			push	hl			;temporarily store string target address
-			ld	hl,hex_char_table	;use char table to get high-nybble character
-			add	hl,de			;add offset to start of table
-			ld	a,(hl)			;get char
-			pop	hl			;get string target address
-			ld	(hl),a			;store first char of string
-			inc	hl			;point to next string target address
-			ld	a,b			;get original byte back from reg b
-			and	00fh			;mask off high-nybble
-			ld	e,a			;d still has 000h, now de has offset
-			push	hl			;temp store string target address
-			ld	hl,hex_char_table	;start of table
-			add	hl,de			;add offset
-			ld	a,(hl)			;get char
-			pop	hl			;get string target address
-			ld	(hl),a			;store second char of string
-			inc	hl			;point to third location
-			ld	a,000h			;zero to terminate string
-			ld	(hl),a			;store the zero
-			ret				;done
-;
-;Converts a single ASCII hex char to a nybble value
-;Pass char in reg A. Letter numerals must be upper case.
-;Return nybble value in low-order reg A with zeros in high-order nybble if no error.
-;Return 0ffh in reg A if error (char not a valid hex numeral).
-;Also uses b, c, and hl registers.
-hex_char_to_nybble:	ld	hl,hex_char_table
-			ld	b,00fh			;no. of valid characters in table - 1.
-			ld	c,000h			;will be nybble value
-hex_to_nybble_loop:	cp	(hl)			;character match here?
-			jp	z,hex_to_nybble_ok	;match found, exit
-			dec	b			;no match, check if at end of table
-			jp	m,hex_to_nybble_err	;table limit exceded, exit with error
-			inc	c			;still inside table, continue search
-			inc	hl
-			jp	hex_to_nybble_loop
-hex_to_nybble_ok:	ld	a,c			;put nybble value in a
-			ret
-hex_to_nybble_err:	ld	a,0ffh			;error value
-			ret
-;
-;Converts a hex character pair to a byte value
-;Called with location of high-order char in HL
-;If no error carry flag clear, returns with byte value in register A, and
-;HL pointing to next mem location after char pair.
-;If error (non-hex char) carry flag set, HL pointing to invalid char
-hex_to_byte:		ld	a,(hl)			;location of character pair
-			push	hl			;store hl (hex_char_to_nybble uses it)
-			call	hex_char_to_nybble
-			pop	hl			;returns with nybble value in a reg, or 0ffh if error
-			cp	0ffh			;non-hex character?
-			jp	z,hex_to_byte_err	;yes, exit with error
-			sla	a			;no, move low order nybble to high side
-			sla	a
-			sla	a
-			sla	a
-			ld	d,a			;store high-nybble
-			inc	hl			;get next character of the pair
-			ld	a,(hl)
-			push	hl			;store hl
-			call	hex_char_to_nybble
-			pop	hl
-			cp	0ffh			;non-hex character?
-			jp	z,hex_to_byte_err	;yes, exit with error
-			or	d			;no, combine with high-nybble
-			inc	hl			;point to next memory location after char pair
-			scf
-			ccf				;no-error exit (carry = 0)
-			ret
-hex_to_byte_err:	scf				;error, carry flag set
-			ret
-hex_char_table:		defm	"0123456789ABCDEF"	;ASCII hex table
-;
-;Subroutine to get a two-byte address from serial input.
-;Returns with address value in HL
-;Uses locations in RAM for buffer and variables
-address_entry:		ld	hl,buffer		;location for entered string
-			call	get_line		;returns with address string in buffer
-			ld	hl,buffer		;location of stored address entry string
-			call	hex_to_byte		;will get high-order byte first
-			jp	c, address_entry_error	;if error, jump
-			ld	(current_location+1),a	;store high-order byte, little-endian
-			ld	hl,buffer+2		;point to low-order hex char pair
-			call	hex_to_byte		;get low-order byte
-			jp	c, address_entry_error	;jump if error
-			ld	(current_location),a	;store low-order byte in lower memory
-			ld	hl,(current_location)	;put memory address in hl
-			ret
-address_entry_error:	ld	hl,address_error_msg
-			call	write_string
-			jp	address_entry
-;
-;Subroutine to get a decimal string, return a word value
-;Calls decimal_string_to_word subroutine
-decimal_entry:		ld	hl,buffer
-			call	get_line		;returns with DE pointing to terminating zero
-			ld	hl,buffer
-			call	decimal_string_to_word
-			ret	nc			;no error, return with word in hl
-			ld	hl,decimal_error_msg	;error, try again
-			call	write_string
-			jp	decimal_entry
-;
-;Subroutine to convert a decimal string to a word value
-;Call with address of string in HL, pointer to end of string in DE
-;Carry flag set if error (non-decimal char)
-;Carry flag clear, word value in HL if no error.
-decimal_string_to_word:	ld	b,d
-			ld	c,e			;use BC as string pointer
-			ld	(current_location),hl	;store addr. of start of buffer in RAM word variable
-			ld	hl,000h			;starting value zero
-			ld	(current_value),hl
-			ld	hl,decimal_place_value	;pointer to values
-			ld	(value_pointer),hl
-decimal_next_char:	dec	bc			;next char in string (moving right to left)
-			ld	hl,(current_location)	;check if at end of decimal string
-			scf				;get ready to subtract de from buffer addr.
-			ccf				;set carry to zero (clear)
-			sbc	hl,bc			;keep going if bc > or = hl (buffer address)
-			jp	c,decimal_continue	;borrow means bc > hl
-			jp	z,decimal_continue	;z means bc = hl
-			ld	hl,(current_value)	;return if de < buffer address (no borrow)
-			scf				;get value back from RAM variable
-			ccf
-			ret				;return with carry clear, value in hl
-decimal_continue:	ld	a,(bc)			;next char in string (right to left)
-			sub	030h			;ASCII value of zero char
-			jp	m,decimal_error		;error if char value less than 030h
-			cp	00ah			;error if byte value > or = 10 decimal
-			jp	p,decimal_error		;a reg now has value of decimal numeral
-			ld	hl,(value_pointer)	;get value to add an put in de
-			ld	e,(hl)			;little-endian (low byte in low memory)
-			inc	hl
-			ld	d,(hl)
-			inc	hl			;hl now points to next value
-			ld	(value_pointer),hl
-			ld	hl,(current_value)	;get back current value
-decimal_add:		dec	a			;add loop to increase total value
-			jp	m,decimal_add_done	;end of multiplication
-			add	hl,de
-			jp	decimal_add
-decimal_add_done:	ld	(current_value),hl
-			jp	decimal_next_char
-decimal_error:		scf
-			ret
-			jp	decimal_add
-decimal_place_value:	defw	1,10,100,1000,10000
-;
-;Memory dump
-;Displays a 256-byte block of memory in 16-byte rows.
-;Called with address of start of block in HL
-memory_dump:		ld	(current_location),hl	;store address of block to be displayed
-			ld	a,000h
-			ld	(byte_count),a		;initialize byte count
-			ld	(line_count),a		;initialize line count
-			jp	dump_new_line
-dump_next_byte:		ld	hl,(current_location)	;get byte address from storage,
-			ld	a,(hl)			;get byte to be converted to string
-			inc	hl			;increment address and
-			ld	(current_location),hl	;store back
-			ld	hl,buffer		;location to store string
-			call	byte_to_hex_string	;convert
-			ld	hl,buffer		;display string
-			call	write_string
-			ld	a,(byte_count)		;next byte
-			inc	a
-			jp	z,dump_done		;stop when 256 bytes displayed
-			ld	(byte_count),a		;not finished yet, store
-			ld	a,(line_count)		;end of line (16 characters)?
-			cp	00fh			;yes, start new line
-			jp	z,dump_new_line
-			inc	a			;no, increment line count
-			ld	(line_count),a
-			ld	a,020h			;print space
-			call	write_char
-			jp	dump_next_byte		;continue
-dump_new_line:		ld	a,000h			;reset line count to zero
-			ld	(line_count),a			
-			call	write_newline
-			ld	hl,(current_location)	;location of start of line
-			ld	a,h			;high byte of address
-			ld	hl, buffer
-			call	byte_to_hex_string	;convert
-			ld	hl,buffer
-			call	write_string		;write high byte
-			ld	hl,(current_location)
-			ld	a,l			;low byte of address
-			ld	hl, buffer
-			call	byte_to_hex_string	;convert
-			ld	hl,buffer
-			call	write_string		;write low byte
-			ld	a,020h			;space
-			call	write_char
-			jp	dump_next_byte		;now write 16 bytes
-dump_done:		ld	a,000h
-			ld	hl,buffer
-			ld	(hl),a			;clear buffer of last string
-			call	write_newline
-			ret
-;
-;Memory load
-;Loads RAM memory with bytes entered as hex characters
-;Called with address to start loading in HL
-;Displays entered data in 16-byte rows.
-memory_load:		ld	(current_location),hl
-			ld	hl,data_entry_msg
-			call	write_string
-			jp	load_new_line
-load_next_char:		call	get_char
-			cp	00dh			;return?
-			jp	z,load_done		;yes, quit
-			ld	(buffer),a
-			call	get_char
-			cp	00dh			;return?
-			jp	z,load_done		;yes, quit
-			ld	(buffer+1),a
-			ld	hl,buffer
-			call	hex_to_byte
-			jp	c,load_data_entry_error	;non-hex character
-			ld	hl,(current_location)	;get byte address from storage,
-			ld	(hl),a			;store byte
-			inc	hl			;increment address and
-			ld	(current_location),hl	;store back
-			ld	a,(buffer)
-			call	write_char
-			ld	a,(buffer+1)
-			call	write_char
-			ld	a,(line_count)		;end of line (16 characters)?
-			cp	00fh			;yes, start new line
-			jp	z,load_new_line
-			inc	a			;no, increment line count
-			ld	(line_count),a
-			ld	a,020h			;print space
-			call	write_char
-			jp	load_next_char		;continue
-load_new_line:		ld	a,000h			;reset line count to zero
-			ld	(line_count),a
-			call	write_newline
-			jp	load_next_char		;continue
-load_data_entry_error:	call	write_newline
-			ld	hl,data_error_msg
-			call	write_string
-			ret
-load_done:		call	write_newline
-			ret
-;
-;Get one ASCII character from the serial port.
-;Returns with char in A reg. No error checking.
-get_char:		in 	a,(0x1F)			;get status
-			and 	001h			;check RxRDY bit
-			jp 	z,get_char		;not ready, loop
-			in 	a,(0x1E)			;get char
-			ret
-;
-;Subroutine to start a new line
-write_newline:		ld	a,00dh			;ASCII carriage return character
-			call	write_char
-			ld	a,00ah			;new line (line feed) character
-			call	write_char
-			ret
-;
-;Subroutine to read one disk sector (128 bytes)
-;Address to place data passed in HL
-;LBA bits 0 to 7 passed in C, bits 8 to 15 passed in B
-;LBA bits 16 to 23 passed in E
-disk_read:
-			ld	a,c
-			out	(0bh),a		;lba bits 0 - 7
-			ld	a,b
-			out	(0ch),a		;lba bits 8 - 15
-			ld	a,e
-			out	(0dh),a		;lba bits 16 - 23
-			ld	a,20h		;Read sector command
-			out	(0fh),a
-rd_wait_for_DRQ_set:	in	a,(0fh)		;read status
-			and	08h		;DRQ bit
-			jp	z,rd_wait_for_DRQ_set	;loop until bit set
-read_loop:		in	a,(08h)		;get data
-			ld	(hl),a
-			inc	hl
-			in	a,(0fh)		;check status
-			and	08h		;DRQ bit
-			jp	nz,read_loop	;loop until cleared
-			ret
-;
-;Subroutine to write one disk sector (128 bytes)
-;Address of data to write to disk passed in HL
-;LBA bits 0 to 7 passed in C, bits 8 to 15 passed in B
-;LBA bits 16 to 23 passed in E
-disk_write:
-			ld	a,c
-			out	(0bh),a		;lba bits 0 - 7
-			ld	a,b
-			out	(0ch),a		;lba bits 8 - 15
-			ld	a,e
-			out	(0dh),a		;lba bits 16 - 23
-			ld	a,30h		;Write sector command
-			out	(0fh),a
-wr_wait_for_DRQ_set:	in	a,(0fh)		;read status
-			and	08h		;DRQ bit
-			jp	z,wr_wait_for_DRQ_set	;loop until bit set			
-write_loop:		ld	a,(hl)
-			out	(08h),a		;write data
-			inc	hl
-			in	a,(0fh)		;read status
-			and	08h		;check DRQ bit
-			jp	nz,write_loop	;write until bit cleared
-			ret
-;
-;Strings used in subroutines
-length_entry_string:	defm	"Enter length of file to load (decimal): ",0
-dump_entry_string:	defm	"Enter no. of bytes to dump (decimal): ",0
-LBA_entry_string:	defm	"Enter LBA (decimal, 0 to 65535): ",0
-erase_char_string:	defm	008h,01bh,"[K",000h	;ANSI sequence for backspace, erase to end of line.
-address_entry_msg:	defm	"Enter 4-digit hex address (use upper-case A through F): ",0
-address_error_msg:	defm	13,10,"Error: invalid hex character, try again: ",0
-data_entry_msg:		defm	"Enter hex bytes, hit return when finished.",13,10,0
-data_error_msg:		defm	"Error: invalid hex byte.",13,10,0
-decimal_error_msg:	defm	13,10,"Error: invalid decimal number, try again: ",0
-;
-;Simple monitor program for CPUville Z80 computer with serial interface.
-monitor_cold_start:	ld	sp,ROM_monitor_stack
-			call	initialize_port
-			ld	hl,monitor_message
-			call	write_string
-monitor_warm_start:	call	write_newline		;routine program return here to avoid re-initialization of port
-			ld	a,03eh			;cursor symbol
-			call	write_char
-			ld	hl,buffer
-			call	get_line		;get monitor input string (command)
-			call	write_newline
-			call	parse			;interprets command, returns with address to jump to in HL
-			jp	(hl)
-;
-;Parses an input line stored in buffer for available commands as described in parse table.
-;Returns with address of jump to action for the command in HL
-parse:			ld	bc,parse_table		;bc is pointer to parse_table
-parse_start:		ld	a,(bc)			;get pointer to match string from parse table
-			ld	e,a
-			inc	bc
-			ld	a,(bc)			
-			ld	d,a			;de will is pointer to strings for matching
-			ld	a,(de)			;get first char from match string
-			or	000h			;zero?
-			jp	z,parser_exit		;yes, exit no_match
-			ld	hl,buffer		;no, parse input string 
-match_loop:		cp	(hl)			;compare buffer char with match string char
-			jp	nz,no_match		;no match, go to next match string
-			or	000h			;end of strings (zero)?
-			jp	z,parser_exit		;yes, matching string found
-			inc	de			;match so far, point to next char in match string
-			ld	a,(de)			;get next character from match string
-			inc	hl			;and point to next char in input string
-			jp	match_loop		;check for match
-no_match:		inc	bc			;skip over jump target to
-			inc	bc
-			inc	bc			;get address of next matching string
-			jp	parse_start
-parser_exit:		inc	bc			;skip to address of jump for match
-			ld	a,(bc)
-			ld	l,a
-			inc	bc
-			ld	a,(bc)
-			ld	h,a			;returns with jump address in hl
-			ret
-;
-;Actions to be taken on match
-;
-;Memory dump program
-;Input 4-digit hexadecimal address
-;Calls memory_dump subroutine
-dump_jump:		ld	hl,dump_message		;Display greeting
-			call	write_string
-			ld	hl,address_entry_msg	;get ready to get address
-			call	write_string
-			call	address_entry		;returns with address in HL
-			call	write_newline
-			call	memory_dump
-			jp	monitor_warm_start
-;
-;Hex loader, displays formatted input
-load_jump:		ld	hl,load_message		;Display greeting
-			call	write_string		;get address to load
-			ld	hl,address_entry_msg	;get ready to get address
-			call	write_string
-			call	address_entry
-			call	write_newline
-			call	memory_load
-			jp	monitor_warm_start
-;
-;Jump and run do the same thing: get an address and jump to it.
-run_jump:		ld	hl,run_message		;Display greeting
-			call	write_string
-			ld	hl,address_entry_msg	;get ready to get address
-			call	write_string
-			call	address_entry
-			jp	(hl)
-;
-;Help and ? do the same thing, display the available commands
-help_jump:		ld	hl,help_message
-			call	write_string
-			ld	bc,parse_table		;table with pointers to command strings
-help_loop:		ld	a,(bc)			;displays the strings for matching commands,
-			ld	l,a			;getting the string addresses from the
-			inc	bc			;parse table
-			ld	a,(bc)			;pass address of string to hl through a reg
-			ld	h,a
-			ld	a,(hl)			;hl now points to start of match string
-			or	000h			;exit if no_match string
-			jp	z,help_done
-			push	bc			;write_char uses b register
-			ld	a,020h			;space char
-			call	write_char
-			pop	bc
-			call	write_string		;writes match string
-			inc	bc			;pass over jump address in table
-			inc	bc
-			inc	bc
-			jp	help_loop
-help_done:		jp	monitor_warm_start
-;
-;Binary file load. Need both address to load and length of file
-bload_jump:		ld	hl,bload_message
-			call	write_string
-			ld	hl,address_entry_msg
-			call	write_string
-			call	address_entry
-			call	write_newline
-			push	hl
-			ld	hl,length_entry_string
-			call	write_string
-			call	decimal_entry
-			ld	b,h
-			ld	c,l
-			ld	hl,bload_ready_message
-			call	write_string
-			pop	hl
-			call	bload
-			jp	monitor_warm_start
-;
-;Binary memory dump. Need address of start of dump and no. bytes
-bdump_jump:		ld	hl,bdump_message
-			call	write_string
-			ld	hl,address_entry_msg
-			call	write_string
-			call	address_entry
-			call	write_newline
-			push	hl
-			ld	hl,dump_entry_string
-			call	write_string
-			call	decimal_entry
-			ld	b,h
-			ld	c,l
-			ld	hl,bdump_ready_message
-			call	write_string
-			call	get_char
-			pop	hl
-			call	bdump
-			jp	monitor_warm_start
-;Disk read. Need memory address to place data, LBA of sector to read
-diskrd_jump:		ld	hl,diskrd_message
-			call	write_string
-			ld	hl,address_entry_msg
-			call	write_string
-			call	address_entry
-			call	write_newline
-			push	hl
-			ld	hl,LBA_entry_string
-			call	write_string
-			call	decimal_entry
-			ld	b,h
-			ld	c,l
-			ld	e,00h
-			pop	hl
-			call	disk_read
-			jp	monitor_warm_start
-diskwr_jump:		ld	hl,diskwr_message
-			call	write_string
-			ld	hl,address_entry_msg
-			call	write_string
-			call	address_entry
-			call	write_newline
-			push	hl
-			ld	hl,LBA_entry_string
-			call	write_string
-			call	decimal_entry
-			ld	b,h
-			ld	c,l
-			ld	e,00h
-			pop	hl
-			call	disk_write
-			jp	monitor_warm_start
-boot_jump:		ld	hl,1100h
-			ld	bc,0000h
-			ld	e,00h
-			call	disk_read
-			jp	1100h
-;Prints message for no match to entered command
-no_match_jump:		ld	hl,no_match_message
-			call	write_string
-			ld	hl, buffer
-			call	write_string
-			jp	monitor_warm_start
-;
-;Monitor data structures:
-;
-monitor_message: 	defm	27,91,50,74,27,91,72,13,10,"ROM Ver. 9",13,10,0
-no_match_message:	defm	"? ",0
-help_message:		defm	"Commands implemented:",13,10,0
-dump_message:		defm	"Displays a 256-byte block of memory.",13,10,0
-load_message:		defm	"Enter hex bytes starting at memory location.",13,10,0
-run_message:		defm	"Will jump to (execute) program at address entered.",13,10,0
-bload_message:		defm	"Loads a binary file into memory.",13,10,0
-bload_ready_message:	defm	13,10,"Ready to receive, start transfer.",0
-bdump_message:		defm	"Dumps binary data from memory to serial port.",13,10,0
-bdump_ready_message:	defm	13,10,"Ready to send, hit any key to start.",0
-diskrd_message:		defm	"Reads one sector from disk to memory.",13,10,0
-diskwr_message:		defm	"Writes one sector from memory to disk.",13,10,0
-;Strings for matching:
-dump_string:		defm	"dump",0
-load_string:		defm	"load",0
-jump_string:		defm	"jump",0
-run_string:		defm	"run",0
-question_string:	defm	"?",0
-help_string:		defm	"help",0
-bload_string:		defm	"bload",0
-bdump_string:		defm	"bdump",0
-diskrd_string:		defm	"diskrd",0
-diskwr_string:		defm	"diskwr",0
-boot_string:		defm	"boot",0
-no_match_string:	defm	0,0
-;Table for matching strings to jumps
-parse_table:		defw	dump_string,dump_jump,load_string,load_jump
-			defw	jump_string,run_jump,run_string,run_jump
-			defw	question_string,help_jump,help_string,help_jump
-			defw	bload_string,bload_jump,bdump_string,bdump_jump
-			defw	diskrd_string,diskrd_jump,diskwr_string,diskwr_jump
-			defw	boot_string,boot_jump
-			defw	no_match_string,no_match_jump
-