diff --git a/screen.S b/screen.S
new file mode 100644
index 0000000..b9990cb
--- /dev/null
+++ b/screen.S
@@ -0,0 +1,198 @@
+
+	rel
+	mx %11
+
+	ent erase_line
+	ent erase_line_0
+	ent erase_line_1
+	ent erase_line_2
+
+erase_line
+; a = 0 - erase x - eol (inclusive)
+; a = 1 - erase 0 - x (inclusive)
+; a = 2 - erase 0 - eol
+	cmp #2
+	bcs :rts
+	asl
+	tax
+	jmp (:table,x)
+:rts rts
+
+:table
+	dw erase_line_0
+	dw erase_line_1
+	dw erase_line_2
+
+erase_line_2
+* erase entire line.
+	php
+	rep #$30
+	ldy #38
+	lda #"  "
+:loop
+	sta [text01],y
+	sta (text00),y
+	dey
+	dey
+	bpl :loop
+	plp
+	rts
+
+	mx %11
+
+erase_line_0
+* erase to eol
+
+	lda x
+	lsr
+	tay
+	lda #" "
+	bcs :half
+:loop
+	sta [text01],y
+:half	sta (text00),y
+	iny
+	cpy #40
+	bcc :loop
+	rts
+
+erase_line_1
+* erase to x (inclusive)
+
+	lda x
+	lsr
+	tay
+	lda #" "
+	bcc :half
+
+:loop
+	sta (text00),y
+:half	sta [text01],y
+	dey
+	bpl :loop
+	rts
+
+
+erase_screen	ent
+; a = 0 - erase [cursor, end] (inclusive)
+; a = 1 - erase [start, cursor] (inclusive)
+; a = 2 - erase [start, end]
+	cmp #2
+	bcs :rts
+	asl
+	tax
+	jmp (:table,x)
+:rts rts
+
+:table
+	dw erase_screen_0
+	dw erase_screen_1
+	dw erase_screen_2	
+
+erase_screen_2	ent
+* erase the entire screen.
+	php
+	rep #$30
+	lda #"  " ; high bit set.
+
+c00	cc $0400
+c01	cc $0480
+c02	cc $0500
+c03	cc $0580
+c04	cc $0600
+c05	cc $0680
+c06	cc $0700
+c07	cc $0780
+c08	cc $0428
+c09	cc $04a8
+c10	cc $0528
+c11	cc $05a8
+c12	cc $0628
+c13	cc $06a8
+c14	cc $0728
+c15	cc $07a8
+c16	cc $0450
+c17	cc $04d0
+c18	cc $0550
+c19	cc $05d0
+c20	cc $0650
+c21	cc $06d0
+c22	cc $0750
+c23	cc $07d0
+	plp
+	rts
+
+	mx %11
+
+erase_screen_0	ent
+* erase from cursor to the end.
+	mx %11
+	ldx #0 ; for jmp (,x)
+	lda x
+	ora y
+	beq :all
+
+	lda x
+	beq :x0
+	jsr erase_line_0
+	lda y
+	inc
+	bra :x1
+:x0
+	lda y
+:x1	cmp #23
+	bcs :rts
+	asl
+	tax
+:all	php ; clear_table will plp.
+	rep #$30
+	lda #"  "
+	jmp (clear_table,x)
+
+:rts	rts
+
+
+erase_screen_1	ent
+* erase from start to cursor.
+	jsr erase_line_1
+	lda y
+	bne :ok
+	rts
+:ok
+	php
+	rep #$30
+	lda y
+	dey
+	asl
+	tax
+	lda #"  "
+	jmp (:clear_table,x)
+:clear_table
+
+
+c23	cc $07d0
+c22	cc $0750
+c21	cc $06d0
+c20	cc $0650
+c19	cc $05d0
+c18	cc $0550
+c17	cc $04d0
+c16	cc $0450
+c15	cc $07a8
+c14	cc $0728
+c13	cc $06a8
+c12	cc $0628
+c11	cc $05a8
+c10	cc $0528
+c09	cc $04a8
+c08	cc $0428
+c07	cc $0780
+c06	cc $0700
+c05	cc $0680
+c04	cc $0600
+c03	cc $0580
+c02	cc $0500
+c01	cc $0480
+c00	cc $0400
+	plp
+	rts
\ No newline at end of file
diff --git a/table.py b/table.py
new file mode 100644
index 0000000..e11e9c3
--- /dev/null
+++ b/table.py
@@ -0,0 +1,73 @@
+
+
+import sys
+
+
+special = {
+}
+for x in range(0,0x20): special[chr(x)] = '^' + chr(0x40 + x)
+
+cmap = {
+	'\'': '\'',
+	'\"': '\"',
+	'?': '?',
+	'\\': '\\',
+	'a': '\a',
+	'b': '\b',
+	'f': '\f',
+	'n': '\n',
+	'r': '\r',
+	't': '\t',
+	'v': '\v',
+}
+
+
+
+argv = sys.argv[1:]
+
+chars = []
+for arg in argv:
+	# ^X is a control character
+	if len(arg) == 2 and arg[0] == '^':
+		c = chr(ord(arg[1]) & 0x1f)
+		chars.append(c)
+		continue
+	# \X is an escaped character
+	if len(arg) == 2 and arg[0] == '\\':
+		c = arg[1]
+		if c in cmap: chars.append(cmap[c])
+		continue
+
+	# X-Y is a range of characters.
+	if len(arg) == 4 and arg[1] == '-':
+		a = arg[0]
+		b = arg[2]
+		for c in range(ord(a),ord(b)+1):
+			chars.append(chr(c))
+		continue
+
+	chars.extend(arg)
+
+chars = list(set(chars))
+chars.sort()
+
+if not chars: exit(1)
+
+mmin = ord(chars[0])
+mmax = ord(chars[-1])
+
+print(":MIN\tequ {}".format(mmin))
+print(":MAX\tequ {}".format(mmax))
+print()
+
+
+
+
+print(":table")
+for x in range(mmin, mmax+1):
+	c = chr(x)
+	print("\tdw $0\t; {}".format(special.get(c, c)))
+
+# for c in chars:
+# 	x = ord(c)
+# 	print("\tdw $0\t; {}".format(special.get(c, c)))
diff --git a/vt.equ.S b/vt.equ.S
new file mode 100644
index 0000000..9d13b58
--- /dev/null
+++ b/vt.equ.S
@@ -0,0 +1,60 @@
+
+st_vt52		equ 0
+st_vt52_esc	equ 2
+st_vt52_dca	equ 4
+st_vt100	equ 6
+st_vt100_esc	equ 8
+st_vt100_csi	equ 10
+st_vt100_csi_2	equ 12
+st_vt100_esc_pound	equ 14 ; #
+st_vt100_esc_lparen	equ 16 ; (
+st_vt100_esc_rparen	equ 18 ; )
+
+st_vt100_esc_bad	equ 20
+st_vt100_csi_bad	equ 22
+
+ESC	equ $1b
+
+
+	dum 0
+state	ds 2
+x	ds 2
+y	ds 2
+DECTM	ds 2 ; top margin
+DECBM	ds 2 ; bottom margin
+
+LOCAL	ds 2 ; local mode
+DECANM	ds 2 ; ansi/vt52
+DECKPAM ds 2 ; alternate keypad
+DECCKM	ds 2 ; cursor key modes
+DECOM	ds 2 ; origin
+DECSCNM ds 2 ; screen mode
+DECAWM	ds 2 ; wrap
+DECARM	ds 2 ; auto repeat
+
+
+LNM	ds 2 ; new line
+SGR	ds 2 ; graphics, bit 1 = bold, 4 = underscore, 5 = blink, 7 = inverse
+
+* not supported
+
+*CHARSET	ds 2 ; 
+*GRAPHICS	ds 2 ; 
+
+*DECCOLM ds 2 ; character per line (80/132)
+*DECINLM ds 2 ; interlace
+*DECSCLM ds 2 ; scroll mode
+
+* DECDHL - double height line
+* DECDWL - double width line
+
+
+* parameters
+MAX_PCOUNT	equ 8
+pcount	ds	2
+parms	ds	MAX_PCOUNT
+pmod	ds	2
+
+r0	ds	2
+
+	dend
diff --git a/vt100.S b/vt100.S
new file mode 100644
index 0000000..0cfbf3a
--- /dev/null
+++ b/vt100.S
@@ -0,0 +1,177 @@
+
+
+
+vt100
+	mx %11
+	and #$7f
+	cmp #' '
+	bcs :notctrl
+	asl
+	tax
+	jmp (ctrl,x)
+:notctrl
+	ldx state
+	jmp (:state_table,x)
+
+
+
+:state_table
+	ext vt52_esc,vt52_dca
+	ext vt100_esc,vt100_csi,vt100_csi_2
+	ext vt100_esc_pound,vt100_esc_lparen,vt100_esc_rparen
+
+	dw char
+	dw vt52_esc
+	dw vt52_dca
+	dw char
+	dw vt100_esc
+	dw vt100_csi
+	dw vt100_csi_2
+	dw vt100_esc_pound
+	dw vt100_esc_lparen
+	dw vt100_esc_rparen
+
+
+
+
+
+vt100_csi_bad ent
+	cmp #'@'
+	blt :rts
+	ldx #st_vt100
+	stx state
+:rts	rts
+
+
+
+
+esc_csi
+	stz pcount
+	stz params
+	stz params+1
+	stz csi_private
+	lda #st_csi
+	sta state
+	rts
+
+
+csi
+	inc state
+	inc state
+	cmp #'?'
+	bne csi0
+	lda #$80
+	sta csi_private
+	rts
+
+csi0
+	cmp #';'
+	beq :semi
+	cmp #'0'
+	bcc csi_final
+	cmp #'9'+1
+	bcs csi_final
+:num
+	and #$0f ; 0-9
+	tay ; save
+	ldx pcount
+	lda params,x
+	asl ; x 2
+	sta params,x
+	asl ; x 4
+	asl ; x 8
+	clc
+	adc params,x
+	sta params,x
+	tya
+	clc
+	adc params,x
+	sta params,x
+	rts
+
+
+:semi
+	ldx pcount
+	inx
+	cpx #MAX_PCOUNT
+	bcs :srts
+	stx pcount
+	stz params,x
+
+:srts
+	rts
+
+
+csi_final
+* c, h, l have private modes.
+	bit csi_private
+	bmi :priv
+
+	cmp #:MIN_FINAL
+	bcc :rts
+	cmp #:MAX_FINAL+1
+	bcs :rts
+	asl
+	tax
+	jmp (:table,x)
+:rts	rts
+
+:priv
+	cmp #:MIN_FINAL_PRIV
+	bcc :rts
+	cmp #:MAX_FINAL_PRIV+1
+	bcs :rts
+	asl
+	tax
+	jmp (:table_priv,x)
+
+
+csi
+*
+* ESC [ encountered.
+*
+* ? -> DEC private
+* 0-9 -> parameter value
+* ; parameter delim
+* other - final character.
+
+	cmp #'0'
+	blt :notnum
+	cmp #'9'+1
+	bge :notnum
+
+	sep #$30
+	and #$0f
+	tay
+	ldx pcount
+	lda parms,x
+	asl
+	pha
+	asl
+	asl
+	clc
+	adc 1,s
+	sta 1,s
+	tya
+	adc 1,s
+	ply
+	sta parms,x
+	sep #$30
+]rts	rts
+:notnum
+	cmp #';'
+	bne :notsemi
+	ldx pcount
+	cpx #MAXPCOUNT
+	bge ]rts
+	inx
+	stx pcount
+	stz parms,
+	stz parms+1,x
+]rts	rts
+:notsemi
+	cmp #'?'
+	bne :final
+	sta ptype
+	rts
+:final
\ No newline at end of file
diff --git a/vt100.csi.S b/vt100.csi.S
new file mode 100644
index 0000000..3280282
--- /dev/null
+++ b/vt100.csi.S
@@ -0,0 +1,413 @@
+
+
+
+	rel
+	xc
+	xc
+
+	use vt.equ
+
+
+vt100_csi ent
+	inc state
+	inc state
+
+	stz pcount
+	stz parms
+	stz parms+1 ; some assume 2 parms.
+	stz pmod
+
+	tay ; save for modifier
+	cmp #:MIN
+	blt :bad
+	cmp #:MAX+1
+	bge :bad
+	sec
+	sbc #:MIN
+	asl
+	tax
+	jmp (:table,x)
+:bad
+	ldx #st_vt100
+	stx state
+:rts	rts
+
+:table
+
+* 0123456789;ycnlhgrqJKmABCDHf
+
+* based on testing - 
+* everything except '0' - '?' and control chars
+* will finish.
+* '?' only matters for h/l
+*  a misplaced ? (or anything in '0' - '?', except 0-9;)
+* will cancel the sequence AFTER it's finished.
+* < = > ? are allowed as an initial modifier but only '?' is private
+* a mis-placed < = > ? will prevent 0x20-0x2f from terminating the sequence.
+
+:MIN	equ 48
+:MAX	equ 121
+:table
+	dw :digit	; 0
+	dw :digit	; 1
+	dw :digit	; 2
+	dw :digit	; 3
+	dw :digit	; 4
+	dw :digit	; 5
+	dw :digit	; 6
+	dw :digit	; 7
+	dw :digit	; 8
+	dw :digit	; 9
+	dw digit	; :
+	dw semi
+	dw :rts	; <
+	dw :rts	; =
+	dw :rts	; >
+	dw :modifier	; ?
+	dw $0	; @
+	dw $0	; A
+	dw $0	; B
+	dw $0	; C
+	dw $0	; D
+	dw $0	; E
+	dw $0	; F
+	dw $0	; G
+	dw $0	; H
+	dw $0	; I
+	dw $0	; J
+	dw $0	; K
+	dw $0	; L
+	dw $0	; M
+	dw $0	; N
+	dw $0	; O
+	dw $0	; P
+	dw $0	; Q
+	dw $0	; R
+	dw $0	; S
+	dw $0	; T
+	dw $0	; U
+	dw $0	; V
+	dw $0	; W
+	dw $0	; X
+	dw $0	; Y
+	dw $0	; Z
+	dw $0	; [
+	dw $0	; \
+	dw $0	; ]
+	dw $0	; ^
+	dw $0	; _
+	dw $0	; `
+	dw $0	; a
+	dw $0	; b
+	dw $0	; c
+	dw $0	; d
+	dw $0	; e
+	dw $0	; f
+	dw $0	; g
+	dw $0	; h
+	dw $0	; i
+	dw $0	; j
+	dw $0	; k
+	dw $0	; l
+	dw $0	; m
+	dw $0	; n
+	dw $0	; o
+	dw $0	; p
+	dw $0	; q
+	dw $0	; r
+	dw $0	; s
+	dw $0	; t
+	dw $0	; u
+	dw $0	; v
+	dw $0	; w
+	dw $0	; x
+	dw $0	; y
+
+
+:digit
+	lsr ; undo asl
+	sta parms
+	rts
+:modifier
+	ldx #$40 ; bit -> v
+	stx pmod
+	rts
+
+
+vt100_csi_2 ent
+
+	; if < '0' and invalid modifier, don't terminate.
+	bit pmod
+	bmi :badmod
+	cmp #'@'
+	blt :0
+	ldx #st_vt100
+	stx state
+
+:0	cmp #:MIN
+	blt :bad
+	cmp #:MAX+1
+	bge :bad
+	sec
+	sbc #:MIN
+	jmp (:table,x)
+
+:badmod
+	cmp #'@'
+	blt :rts
+
+:bad
+	ldx #st_vt100
+	stx state
+:rts	rts
+
+:MIN	equ 48
+:MAX	equ 121
+:table
+	dw digit	; 0
+	dw digit	; 1
+	dw digit	; 2
+	dw digit	; 3
+	dw digit	; 4
+	dw digit	; 5
+	dw digit	; 6
+	dw digit	; 7
+	dw digit	; 8
+	dw digit	; 9
+	dw digit	; :
+	dw semi
+	dw :modifier	; <
+	dw :modifier	; =
+	dw :modifier	; >
+	dw :modifier	; ?
+
+:modifier
+	lda #$80
+	sta pmod
+	rts
+
+semi
+	ldx pcount
+	cpx #MAX_PCOUNT
+	bge :rts
+
+	inx
+	stx pcount
+	stz parms,x
+:rts	rts
+
+* parameter digit.  clamped to 255 (250+ rounds up to 255)
+* in 132 is the largest valid parameter so this is ok.
+digit
+	lsr ; undo asl
+	sta r0
+	ldx pcount
+	lda parms,x
+*	cmp #255
+*	beq :rts
+	cmp #25
+	bge :v
+
+	tay
+	lda :table,y
+*	clc ; cleared via cmp
+	adc r1
+	sta parms,x
+
+
+:rts
+	rts
+:v
+	lda #$255
+	sta parms,x
+	rts
+
+:table	da 0,10,20,30,40,50,60,70,80,90
+	da 100,110,120,130,140,150,160,170,180,190
+	da 200,210,220,230,240,250
+
+
+
+
+
+set_mode
+	; esc [ ... h (vt100)
+	; esc [ ? ... h (private)
+	ldy #$80
+	bra mode_common
+
+reset_mode
+	; esc [ ... l (vt100)
+	; esc [ ? ... l (private)
+	ldy #0
+
+mode_common
+	inc pcount
+	ldx #0
+:loop	lda parms,x
+	cmp #:MIN
+	blt :next
+	cmp #:MAX+1
+	bgt :next
+	phx
+	asl
+	tax
+	jsr (:table,x)
+	plx
+
+:next	inx
+	cpx pcount
+	blt :loop
+:rts	rts
+
+:MIN equ 0
+:MAX equ 20
+:table
+	dw :rts ; error
+	dw mode_DECCKM
+	dw mode_DECANM
+	dw :rts ; DECCOLM
+	dw :rts ; DECSCLM
+	dw mode_DECSCNM
+	dw mode_DECOM
+	dw mode_DECAWM
+	dw mode_DECARM
+	dw :rts ; DECINLM
+	dw :rts ; 10
+	dw :rts ; 11
+	dw :rts ; 12
+	dw :rts ; 13
+	dw :rts ; 14
+	dw :rts ; 15
+	dw :rts ; 16
+	dw :rts ; 17
+	dw :rts ; 18
+	dw :rts ; 19
+	dw mode_LNM
+*:mask	dw 0,$40,$40,$40,$40,$40,$40,$40,$40,$40
+*	dw 0,0,0,0,0,0,0,0,0,0,0
+
+
+mode_DECCKM
+	bit pmod
+	bvc :rts
+
+	sty DECCKM
+:rts	rts
+
+mode_DECANM
+	bit pmod
+	bvc :rts
+
+	sty DECANM
+	cpy #0
+	bne :rts
+* switch to vt52 mode
+	ldx #st_vt52
+	stx state
+:rts	rts
+
+
+*mode_DECCOLM
+*	sty DECCOLM
+*	rts
+
+
+mode_DECSCNM
+	bit pmod
+	bvc :rts
+
+* todo - invert on-screen characters?
+	sty DECSCNM
+:rts	rts
+
+mode_DECOM
+	bit pmod
+	bvc :rts
+
+	sty DECOM
+	; move to the new home position
+	stz x
+	stz y
+	cpy #0
+	beq :rts
+	lda #DECTM
+	sta y
+
+	phy
+	jsr update_cursor
+	ply
+
+:rts	rts
+
+mode_DECAWM
+	bit pmod
+	bvc :rts
+
+	sty DECAWM
+:rts	rts
+
+mode_DECARM
+	bit pmod
+	bvc :rts
+
+	sty DECARM
+:rts	rts
+
+mode_LNM
+	bit pmod
+	bvs :rts
+
+	sty LNM
+:rts	rts
+
+
+char_attr
+* esc [ ... m
+	inc pcount
+	ldx #0
+:loop	lda parms,x
+	cmp #8
+	bge :next
+	tay
+	lda SGR
+	and :and,y
+	ora :or,y
+	lda :table,y
+	sta SGR
+
+:next	inx
+	cpx pcount
+	blt :loop
+:rts	rts
+
+
+:and	db $00,$ff,$ff,$ff,$ff,$ff,$ff,$ff
+
+:or	db %0000_0000,%0000_0010,%0000_0000,%0000_0000
+	db %0001_0000,%0010_0000,%0000_0000,%1000_0000
+
+
+
+reset_tab
+* ESC H - set tab at current column [vt100.s]
+* ESC [ g, ESC [ 0 g - clear tab at column
+* ESC [ 3 g - clear all tabs
+
+	lda parm
+	beq :0
+	cmp #3
+	beq :3
+	rts
+:0
+	ldx x
+	stz tabs,x
+	rts
+:3
+	ldx #80-1
+:loop	stz tabs,x
+	dex
+	bpl :loop
+	rts
+
+	sav vt100.csi.L
diff --git a/vt100.ctrl.S b/vt100.ctrl.S
new file mode 100644
index 0000000..5a2a166
--- /dev/null
+++ b/vt100.ctrl.S
@@ -0,0 +1,103 @@
+
+
+*control chars
+	ext draw_char,update_cursor
+
+control	ent
+
+	asl
+	tax
+	jmp (:table,x)
+
+:table
+	dw :rts	; ^@
+	dw :rts	; ^A
+	dw :rts	; ^B
+	dw :rts	; ^C
+	dw :rts	; ^D
+	dw enq	; ^E
+	dw :rts	; ^F
+	dw bel	; ^G
+	dw bs	; ^H
+	dw tab	; ^I
+	dw lf	; ^J
+	dw vt	; ^K
+	dw ff	; ^L
+	dw cr	; ^M
+	dw so	; ^N
+	dw si	; ^O
+	dw :rts	; ^P
+	dw xon	; ^Q
+	dw :rts	; ^R
+	dw xoff	; ^S
+	dw :rts	; ^T
+	dw :rts	; ^U
+	dw :rts	; ^V
+	dw :rts	; ^W
+	dw can	; ^X
+	dw :rts	; ^Y
+	dw sub	; ^Z
+	dw esc	; ^[
+	dw :rts	; ^\
+	dw :rts	; ^]
+	dw :rts	; ^^
+	dw :rts	; ^_
+
+:rts	rts
+
+enq
+* send answer back message.
+* answer back message is a user-controllable string of text sent as-is
+* (with no specific terminator character)
+	rts
+bel
+* todo - trigger nice ensoniq beep.
+	rts
+
+
+bs
+* backspace, no wrap
+	lda x
+	beq :rts
+	dec x
+	jmp update_cursor
+:rts	rts
+
+tab
+* go to next tab stop
+	rts
+
+lf
+vt
+ff
+* vt and ff interpreted as lf
+* LNM: also do cr.
+	bit LNM
+	bpl :lnm
+	stz x
+:lnm
+	lda y
+	cmp BM ; bottom margin
+	bne :iny
+	jmp scroll_up
+:iny	inc y
+	jmp update_cursor
+
+cr
+	stz x
+	jmp update_cursor
+
+xon
+xoff
+* flow control...
+	rts
+can
+sub
+* cancel esc sequence and display error character
+	stz state
+	rts
+
+esc
+	lda #st_esc
+	sta state
+	rts
\ No newline at end of file
diff --git a/vt100.esc.S b/vt100.esc.S
new file mode 100644
index 0000000..415d719
--- /dev/null
+++ b/vt100.esc.S
@@ -0,0 +1,164 @@
+
+
+	rel
+	xc
+	xc
+
+	use vt.equ
+
+vt100_esc ent
+* #[()=>cH78DEM
+* based on testing, unspecified chars in the 0x20-0x2f range cause it to gobble
+* chars until 0x30- terminator (which ends the sequence but does not take an action)
+
+* esc 1 -> hangs? [undocumented]
+
+
+	ldx #st_vt100
+	stx state
+
+	cmp #:MIN
+	blt :bad
+	cmp #:MAX+1
+	bge :rts
+	sec
+	sbc #:MIN
+	asl
+	tax
+	jmp (:table,x)
+
+:bad
+	ldx #st_vt100_esc_bad
+	stx state
+:rts
+	rts
+
+:MIN	equ 35
+:MAX	equ 99
+
+:table
+	dw :pound	; #
+	dw :bad	; $
+	dw :bad	; %
+	dw :bad	; &
+	dw :bad	; '
+	dw :lparen	; (
+	dw :rparen	; )
+	dw :bad	; *
+	dw :bad	; +
+	dw :bad	; ,
+	dw :bad	; -
+	dw :bad	; .
+	dw :bad	; /
+	dw :rts	; 0
+	dw :rts	; 1
+	dw :rts	; 2
+	dw :rts	; 3
+	dw :rts	; 4
+	dw :rts	; 5
+	dw :rts	; 6
+	dw esc_7	; 7
+	dw esc_8	; 8
+	dw :rts	; 9
+	dw :rts	; :
+	dw :rts	; ;
+	dw :rts	; <
+	dw esc_eq	; =
+	dw esc_gt	; >
+	dw :rts	; ?
+	dw :rts	; @
+	dw :rts	; A
+	dw :rts	; B
+	dw :rts	; C
+	dw esc_D	; D
+	dw esc_E ; E
+	dw :rts	; F
+	dw :rts	; G
+	dw esc_H	; H
+	dw :rts	; I
+	dw :rts	; J
+	dw :rts	; K
+	dw :rts	; L
+	dw esc_M	; M
+	dw :rts	; N
+	dw :rts	; O
+	dw :rts	; P
+	dw :rts	; Q
+	dw :rts	; R
+	dw :rts	; S
+	dw :rts	; T
+	dw :rts	; U
+	dw :rts	; V
+	dw :rts	; W
+	dw :rts	; X
+	dw :rts	; Y
+	dw :rts	; Z
+	dw :rts	; [
+	dw :rts	; \
+	dw :rts	; ]
+	dw :rts	; ^
+	dw :rts	; _
+	dw :rts	; `
+	dw :rts	; a
+	dw :rts	; b
+	dw esc_c	; c
+
+
+
+:lparen
+	ldx #st_vt100_esc_lparen
+	stx state
+	rts
+
+:rparen
+	ldx #st_vt100_esc_rparen
+	stx state
+	rts
+
+:pound
+	ldx #st_vt100_esc_pound
+	stx state
+	rts
+
+
+esc_7 ; save cursor position, graphic rendition, and character set.
+	rts
+esc_8 ; restore cursor position, graphic rendition, and character set.
+	rts 
+
+esc_eq ; enter alternate keypad mode
+	lda #$80
+	sta DECKPAM
+	rts
+esc_gt ; exit alternate keypad mode
+	stz DECKPAM
+	rts
+
+esc_H ; set tab stop
+	ext set_tab
+	ldx x
+	jmp set_tab
+
+esc_E ; next line
+	stz x
+	; drop through
+esc_D ; index
+	rts
+
+esc_M ; reverse index
+	rts
+
+esc_c ; reset terminal.
+	rts
+
+
+vt100_esc_bad ent
+	cmp #'0'
+	blt :rts
+	ldx #st_vt100
+	stx state
+:rts
+	rts
+
+
+	sav vt100.esc.L
diff --git a/vt100.link.S b/vt100.link.S
new file mode 100644
index 0000000..6276036
--- /dev/null
+++ b/vt100.link.S
@@ -0,0 +1,22 @@
+
+	ovr all
+
+* binary linker
+	lkv 0
+	org $6000
+
+	asm boot.S
+	asm vt100.ctrl.S
+
+
+
+	lnk boot.S
+	pos ; reset
+
+
+	pos EMU_SIZE
+EMU_SIZE	ext 
+EMU_BLOCKS	geq EMU_SIZE+511\512
+
+
+	sav vt100.bin
\ No newline at end of file
diff --git a/vt100.main.S b/vt100.main.S
new file mode 100644
index 0000000..3a2123a
--- /dev/null
+++ b/vt100.main.S
@@ -0,0 +1,147 @@
+vt100
+	mx %11
+	and #$7f
+	cmp #' '
+	bcs :notctrl
+	asl
+	tax
+	jmp (:ctrl_table,x)
+:notctrl
+	ldx state
+	jmp (:state_table,x)
+
+
+
+:state_table
+	ext vt52_esc,vt52_dca_1,vt52_dca_2
+	ext vt100_esc,vt100_csi,vt100_csi_2
+	ext vt100_esc_pound,vt100_esc_lparen,vt100_esc_rparen
+
+	dw char
+	dw vt52_esc
+	dw vt52_dca_1
+	dw vt52_dca_2
+	dw char
+	dw vt100_esc
+	dw vt100_csi
+	dw vt100_csi_2
+	dw vt100_esc_pound
+	dw vt100_esc_lparen
+	dw vt100_esc_rparen
+
+
+:ctrl_table
+	dw ctrl_00,ctrl_01,ctrl_02,ctrl_03
+	dw ctrl_04,ctrl_05,ctrl_06,ctrl_07
+	dw ctrl_08,ctrl_09,ctrl_0a,ctrl_0b
+	dw ctrl_0c,ctrl_0d,ctrl_0e,ctrl_0f
+	dw ctrl_10,ctrl_11,ctrl_12,ctrl_13
+	dw ctrl_14,ctrl_15,ctrl_16,ctrl_17
+	dw ctrl_18,ctrl_19,ctrl_1a,ctrl_1b
+	dw ctrl_1c,ctrl_1d,ctrl_1e,ctrl_1f
+
+
+
+ctrl_00
+ctrl_01
+ctrl_02
+ctrl_03
+ctrl_04
+ctrl_05 ; answer ENQ
+ctrl_06
+ctrl_0e ; G1 character set
+ctrl_0f ; G0 character set
+ctrl_10
+ctrl_11 ; XON
+ctrl_12
+ctrl_13 ; XOFF
+ctrl_14
+ctrl_15
+ctrl_16
+ctrl_17
+ctrl_19
+ctrl_1c
+ctrl_1d
+ctrl_1e
+ctrl_1f
+	rts
+
+
+ctrl_07 ; ring the bell.
+	rts
+
+ctrl_1b ; escape -
+* vt100 - aborts current escape sequence and starts a new one.
+* vt52 - esc esc aborts and starts new 
+* vt50 - esc esc aborts
+	lda DECANM
+	bne :vt52
+	lda #st_vt100_esc
+	sta state
+	rts
+
+:vt52
+	lda #st_vt52_esc
+	sta state
+	rts
+
+ctrl_18
+ctrl_1a
+* vt100 - abort current escape sequence
+* and display error character.
+	lda DECANM
+	bne :vt52
+	lda #st_vt100
+	sta state
+	rts
+
+:vt52
+	lda #st_vt52
+	sta state
+	rts
+
+
+ctrl_09 ; tab
+* vt100 has adjustable tabs.
+	ext tab_table
+
+	ldx x
+lp:
+	cpx #79
+	bcs :rts
+	lda tab_table,x
+	bne :hit
+	inx
+	bra :lp
+
+	stx x
+
+	jmp update_cursor
+:rts	rts
+
+ctrl_0a ; line feed - cursor down w/ scroll
+ctrl_0b ; vertical tab
+ctrl_0c ; form feed.
+
+* if LNM is active, equivalent to CR, LF
+
+	lda #LNM
+	bne :lnm
+	stz x
+:lnm
+
+	lda y
+	cmp #23
+	blt :simple
+
+	lda #" "
+	sta cursor_saved_char
+	jmp scroll_down
+
+:simple
+	inc y
+	jmp update_cursor
+
+ctrl_0d ; carriage return - cursor to column 0.
+	stz x
+	jmp update_cursor
diff --git a/vt100.tabs.S b/vt100.tabs.S
new file mode 100644
index 0000000..5e21e12
--- /dev/null
+++ b/vt100.tabs.S
@@ -0,0 +1,77 @@
+
+
+	rel
+	xc
+	xc
+
+	use vt.equ
+
+
+init_tabs	ent
+
+
+	ldx #80
+:loop	stz tabs,x
+	dex
+	bpl :loop
+
+	lda #72
+	ldy #$80
+:tloop	tax
+	sty tabs,x
+	sec
+	sbc #8
+	bne :tloop
+
+	rts
+*:table	db 8*1,8*2,8*3,8*4,8*5,8*6,8*7,8*8*,8*9
+
+set_tab	ent
+* input x = x
+
+*	ldx x
+	cpx #80
+	bge :rts
+	lda #$80
+	sta tabs,x
+:rts	rts
+
+reset_tab ent
+* input x = x
+
+*	ldx x
+	cpx #80
+	bge :rts
+	stz tabs,x
+:rts	rts
+
+
+reset_all_tabs ent
+
+	ldx #80-1
+:loop	stz tabs,x
+	dex
+	bpl :loop
+	rts	
+
+next_tab_stop ent
+* input x = x
+
+*	ldx x
+	cpx 79
+	bge :80
+
+:loop	bit tabs,x
+	bmi :rts
+	inx
+	cpx #80
+	bcc :loop
+
+
+:80	ldx	#80
+:rts	rts
+
+
+tabs	ds 80
+
+	sav vt100.tabs.L
diff --git a/vt100.vt52.S b/vt100.vt52.S
new file mode 100644
index 0000000..1fd464e
--- /dev/null
+++ b/vt100.vt52.S
@@ -0,0 +1,228 @@
+*
+* vt52 emulation for the vt100
+*
+* ESC < exits 
+
+	lst off
+
+	rel
+	xc
+	xc
+
+	use vt.equ
+
+	ext update_cursor,write_modem,draw_char
+
+
+
+vt52_esc ent
+* ABCDFGHIJKYZ<>=
+
+
+	ldx #st_vt52
+	stx state
+
+	cmp #:MIN
+	blt :rts
+	cmp #:MAX+1
+	bge :rts
+	sec
+	sbc #:MIN
+	asl
+	tax
+	jmp (:table,x)
+
+:rts
+	rts
+
+
+:MIN	equ 60
+:MAX	equ 90
+:table
+	dw esc_lt	; <
+	dw esc_eq	; =
+	dw esc_gt	; >
+	dw :rts		; ?
+	dw :rts		; @
+	dw esc_A	; A
+	dw esc_B	; B
+	dw esc_C	; C
+	dw esc_D	; D
+	dw :rts		; E
+	dw esc_F	; F
+	dw esc_G	; G
+	dw esc_H	; H
+	dw esc_I	; I
+	dw esc_J	; J
+	dw esc_K	; K
+	dw :rts		; L
+	dw :rts		; M
+	dw :rts		; N
+	dw :rts		; O
+	dw :rts		; P
+	dw :rts		; Q
+	dw :rts		; R
+	dw :rts		; S
+	dw :rts		; T
+	dw :rts		; U
+	dw :rts		; V
+	dw :rts		; W
+	dw :rts		; X
+	dw esc_Y	; Y
+	dw esc_Z	; Z
+
+
+
+esc_lt
+* based on testing, this also resets graphics mode
+* (which we don't support anyhow.)
+	lda #$80
+	sta DECANM
+	lda #st_vt100
+	sta state
+	rts
+
+
+esc_eq ; enter alternate keypad mode
+	lda #$80
+	sta DECKPAM
+	rts
+
+esc_gt ; exit alternate keypad mode
+	stz DECKPAM
+	rts
+
+* cursor movement respects the scrolling region.
+esc_A ; cursor up.
+	lda y
+	beq :rts
+	cmp DECTM
+	beq :rts
+	dec y
+	jmp update_cursor
+
+:rts	rts
+
+
+esc_B ; cursor down
+	lda y
+	cmp #79
+	beq :rts
+	cmp DECBM
+	beq :rts
+	iny y
+	jmp update_cursor
+
+:rts	rts
+
+
+esc_C ; cursor right
+
+	lda x
+	cmp #79
+	bcs :rts
+	inc x
+	jmp update_cursor
+:rts	rts
+
+esc_D ; cursor left
+
+	lda x
+	beq :rts
+	dec x
+	jmp update_cursor
+:rts	rts
+
+esc_I ; cursor up w/ line scroll
+* based on testing, scrolling only occurs within the
+* scroll region.
+	rts
+esc_J rts
+esc_K rts
+
+
+esc_H ; cursor home
+	; based on testing, does not respect scrolling region but does
+	; respect origin mode.
+	stz x
+*	stz y
+*	bit DECOM
+*	bpl :go
+	lda DECTM
+	sta y
+
+:go	jmp update_cursor
+
+
+esc_F ; enter graphics mode
+*	lda #%0010
+*	tsb mode
+	rts
+esc_G ; exit graphics mode
+*	lda #%0010
+*	trb mode
+	rts
+
+esc_Y ; direct cursor address
+* vt100 - does not take effect until the end.
+* based on testing, there is internal state information,
+* so esc Y a esc B esc Y b is equivalent to esc Y a b
+*
+* if width exceeded, clamps at right margin.
+* if height exceeded, does not change.
+	lda #st_vt52_dca
+	sta state
+	rts
+
+esc_Z ; terminal identity.
+	; return ESC / Z
+	; based on testing, no display in local mode
+	bit LOCAL
+	bmi :local
+	lda #ESC
+	jsr write_modem
+	lda #'/'
+	jsr write_modem
+	lda #'Z'
+	jmp write_modem
+
+:local	rts
+*	lda #'Z'
+*	jmp draw_char
+
+
+
+vta52_dca ent
+* this differs from esc [ H in that invalid
+* values are ignored rather than clamped.
+* based on testing, does not respect DECOM.
+* based on testing, state is saved if ESC aborts, even
+* if switching to vt100 mode and back or ^X to cancel.
+
+	sec
+	sbc #' '
+
+	bit :tmp
+	bmi :go
+	ora #$80
+	sta :tmp
+	rts
+
+:go	; a = x
+	cmp #80
+	bge :y
+	sta x
+:y	lda :tmp
+	and #$7f
+	cmp #24
+	bge :update
+	sta y
+:update
+	stz :tmp
+	jmp update_cursor
+
+
+:tmp	ds 2
+
+
+	sav vt100.vt52.L