add command-L to toggle local/online

add command-Q to quit.

Since ROM 1 doesn't have _RemoveCDA in ROM, the control panel is only installed in ROM 3.
(TODO -- check at runtime in case launched from GS/OS)

README.md

@@ -0,0 +1,12 @@
+# itty-bitty-vtty
+A vt100 emulator for the Apple IIgs
+
+vt100, modem port, 9600 baud, 8-N-1 (MAME defaults)
+
+A vt100 emulator based on The [User Guide](https://www.vt100.net/docs/vt100-ug/contents.html). Underspecified behavior is tested with MAME's vt100 emulation.
+
+Unimplemented due to hardware limitations:
+
+* alternate character sets
+* graphic rendition (except plain/reverse)
+* 132-column mode

vt.equ.S

@@ -18,6 +18,7 @@ st_vt100_csi_bad	equ 22
 
 ESC	equ $1b
 
+DPAGE	equ $1f00
 
 	dum 0
 state	ds 2
@@ -35,6 +36,7 @@ DECOM	ds 2 ; origin
 DECSCNM ds 2 ; screen mode
 DECAWM	ds 2 ; wrap
 DECARM	ds 2 ; auto repeat
+DECCOLM ds 2 ; character per line (80/132)
 
 
 LNM	ds 2 ; new line
@@ -45,7 +47,6 @@ SGR	ds 2 ; graphics, bit 1 = bold, 4 = underscore, 5 = blink, 7 = inverse
 *CHARSET	ds 2 ; 
 *GRAPHICS	ds 2 ; 
 
-*DECCOLM ds 2 ; character per line (80/132)
 *DECINLM ds 2 ; interlace
 *DECSCLM ds 2 ; scroll mode
 
@@ -81,6 +82,17 @@ mod		ds 2
 * saved cursor
 saved_x	ds 2
 saved_y	ds 2
+saved_decom ds 2
+saved_sgr ds 2
+
+
+* async read/write pointers.
+*
+read_q_head	ds 2
+read_q_tail	ds 2
+write_q_head	ds 2
+write_q_tail	ds 2
+
 
 	do *>256
 	err "too big"

vt100.cda.S

@@ -9,6 +9,8 @@
 	tbx on ; qasm
 
 	use apple2gs.equ
+	use vt.equ
+	use debug
 
 
 * alternate character set
@@ -25,19 +27,78 @@
 * 40-column control panel
 * TODO - if 80 column set in preferences, draw centered in 80-column mode
 
-init_cda ent
+
+	dum 0
+* cda direct page variables
+ptr	ds 2
+	dend
+
+
+*
+* rom 0/1 doesn't include _RemoveCDA in ROM so it can't be removed.
+* additionally, _InstallCDA has bugs.
+* so, for now, disable on ROM 1.
+
+cda_startup ent
 	php
 	rep #$30
+
+	jsr $fe1f ; idroutine.  y = rom
+	cpy #3
+	bcc :nope
+
+*
+* rom 1 IIgs InstallCDA clobbers $3c-$43 on the direct page
+*
+
+	phd
+	pea #0
+	pld
+
 	psl #handle
 	_InstallCDA
+
+	pld
+
+:nope
 	plp
 	rts
 
+cda_shutdown ent
+	mx %00
+
+	jsr $fe1f ; idroutine.  y = rom
+	cpy #3
+	bcc :nope
+
+	phd
+	pea #0
+	pld
+
+
+	psl #handle
+	_RemoveCDA
+
+	pld
+
+:nope
+	rts
+
+
 handle	adrl Header ; can use a fake handle for now, until we need to _RemoveCDA
 Header
 	str 'Virtual Terminal'
 	adrl start
 	adrl shutdown
+* variables.
+page	ds 2
+
+
+MAX_PAGE	equ 8
+pages	dw variables
+	dw hexdump_r
+	dw hexdump_w
+	dw ssc_registers
 
 shutdown
 	mx %00
@@ -58,19 +119,59 @@ start
 	sta SETALTCHAR
 	rep #$30
 
+	stz page
 	jsr clear
 	jsr box
 
+main
+
+	jsr clear_inner
+	ldx page
+	jsr (pages,x)
+
+
 
 :keyloop
+	sep #$30
 	lda KBD
 	bpl :keyloop
 	sta KEYSTROBE
+	rep #$30
 
+	and #$7f
+
+	cmp #$1b
+	beq :exit
+
+	cmp #$08 ; left
+	beq :left
+	cmp #$15
+	beq :right
+	bra :keyloop
+
+:exit
 	pld
 	plb
 	rtl
 
+:left	lda page
+	dec
+	dec
+	bpl :lok
+	lda #MAX_PAGE-2
+:lok	sta page
+	bra main
+
+:right	lda page
+	inc
+	inc
+	cmp #MAX_PAGE
+	bcc :rok
+	lda #0
+:rok	sta page
+	bra main
+
+
 
 clear
 	ldx #23*2
@@ -89,21 +190,38 @@ clear
 	bpl :loop
 	rts
 
+clear_inner
+* clear the inner contents.
+	ldx #16*2
+	lda #"  "
+:loop	ldy text+8,x
+
+]offset	equ 4
+	lup 16
+	sta |0+]offset,y
+]offset	equ ]offset+2
+	--^
+
+	dex
+	dex
+	bpl :loop
+	rts
+
 
 box
 	php
 
 * top line
 	lda #"_ "
-	sta $0400+38
+	sta |line_0+38
 
 	lda #" _"
-	sta $0400
+	sta |line_0
 
 	lda #"__"
 	ldx #34
 
-]loop	sta $0400+2,x
+]loop	sta |line_0+2,x
 	dex
 	dex
 	bpl ]loop
@@ -111,15 +229,15 @@ box
 * bottom line.
 * 'L' = $4c = _ but high 
 	lda #'L '!$8000 ; keep ' ' high ascii.
-	sta $07d0+38
+	sta |line_23+38
 
 	lda #' L'!$0080 ; keep ' ' high ascii.
-	sta $07d0
+	sta |line_23
 
 	lda #'LL'
 	ldx #34
 
-]loop	sta $07d0+2,x
+]loop	sta |line_23+2,x
 	dex
 	dex
 	bpl ]loop
@@ -150,14 +268,14 @@ box
 * title
 	ldx #36
 ]loop	lda :title,x
-	sta |$0480+1,x
+	sta |line_1+1,x
 	dex
 	dex
 	bpl ]loop
 
 	lda #'LL'
 	ldx #36
-]loop	sta |$0500+1,x
+]loop	sta |line_2+1,x
 	dex
 	dex
 	bpl ]loop
@@ -165,7 +283,7 @@ box
 * bottom instructions
 	ldx #:instr_len-2
 ]loop	lda :instr,x
-	sta |$0750+1,x
+	sta |line_22+1,x
 	dex
 	dex
 	bpl ]loop
@@ -187,6 +305,692 @@ box
 	ds 38-18,' ' 
 
 
+* print variables.
+variables
+	php
+	sep #$20
+	jsr local
+	jsr decanm
+	jsr decom
+	jsr deckpam
+	jsr decckm
+	jsr decawm
+	jsr decarm
+	jsr decscnm
+	jsr deccolm
+	jsr lnm
+	jsr sgr
+	jsr dectm
+	jsr decbm
+	jsr decx
+	jsr decy
+	plp
+	rts
+
+local
+	mx %10
+	ldy #line_4+4
+	ldx #:str
+	jsr print_xy_str
+	lda DPAGE+LOCAL
+	jmp print_on_off
+
+:str	asc "LOCAL:   ",00
+
+decanm
+	mx %10
+	ldy #line_5+4
+	ldx #:str
+	jsr print_xy_str
+	lda DPAGE+DECANM
+	bmi :100
+	ldx #:vt52
+	jmp print_xy_str
+
+:100	ldx #:vt100
+	jmp print_xy_str
+
+:str	asc "DECANM:  ",00
+:vt100	asc "vt100",00
+:vt52	asc "vt52",00
+
+
+
+decom
+	mx %10
+	ldy #line_6+4
+	ldx #:str
+	jsr print_xy_str
+	lda DPAGE+DECOM
+	jmp print_on_off
+
+:str	asc "DECOM:   ",00
+
+deckpam
+	mx %10
+	ldy #line_7+4
+	ldx #:str
+	jsr print_xy_str
+	lda DPAGE+DECKPAM
+	jmp print_on_off
+
+:str	asc "DECKPAM: ",00
+
+decckm
+	mx %10
+	ldy #line_8+4
+	ldx #:str
+	jsr print_xy_str
+	lda DPAGE+DECCKM
+	jmp print_on_off
+
+:str	asc "DECCKM:  ",00
+
+
+decawm
+	mx %10
+	ldy #line_9+4
+	ldx #:str
+	jsr print_xy_str
+	lda DPAGE+DECAWM
+	jmp print_on_off
+
+:str	asc "DECAWM:  ",00
+
+decarm
+	mx %10
+	ldy #line_10+4
+	ldx #:str
+	jsr print_xy_str
+	lda DPAGE+DECARM
+	jmp print_on_off
+
+:str	asc "DECARM:  ",00
+
+decscnm
+	mx %10
+	ldy #line_11+4
+	ldx #:str
+	jsr print_xy_str
+	lda DPAGE+DECSCNM
+	jmp print_on_off
+
+:str	asc "DECSCNM: ",00
+
+
+deccolm
+	mx %10
+	ldy #line_12+4
+	ldx #:str
+	jsr print_xy_str
+	lda DPAGE+DECCOLM
+	jmp print_on_off
+
+:str	asc "DECCOLM: ",00
+
+
+lnm
+	mx %10
+	ldy #line_13+4
+	ldx #:str
+	jsr print_xy_str
+	lda DPAGE+LNM
+	jmp print_on_off
+
+:str	asc "LNM:     ",00
+
+
+sgr
+	mx %10
+	ldy #line_14+4
+	ldx #:str
+	jsr print_xy_str
+	lda DPAGE+SGR
+	jmp print_binary
+
+:str	asc "SGR:     ",00
+
+
+dectm
+	mx %10
+	ldy #line_15+4
+	ldx #:str
+	jsr print_xy_str
+	lda DPAGE+DECTM
+	inc
+	jmp print_number
+
+:str	asc "DECTM:   ",00
+
+decbm
+	mx %10
+	ldy #line_16+4
+	ldx #:str
+	jsr print_xy_str
+	lda DPAGE+DECBM
+	inc
+	jmp print_number
+
+:str	asc "DECBM:   ",00
+
+
+decx
+	mx %10
+	ldy #line_17+4
+	ldx #:str
+	jsr print_xy_str
+	lda DPAGE+x
+	and #$7f
+	inc
+	jmp print_number
+
+:str	asc "X:       ",00
+
+decy
+	mx %10
+	ldy #line_18+4
+	ldx #:str
+	jsr print_xy_str
+	lda DPAGE+y
+	inc
+	jmp print_number
+
+:str	asc "Y:       ",00
+
+
+print_xy_str
+	mx %10
+:loop	lda |$0,x
+	beq :end
+	sta |$0,y
+	inx
+	iny
+	bra :loop
+:end	
+	rts
+
+print_on_off
+	mx %10
+	bmi :set
+	ldx #:off
+	jmp print_xy_str
+:set	ldx #:on
+	jmp print_xy_str
+
+:on	asc "on",00
+:off	asc "off",00
+
+print_number
+	debug print_number
+*
+* print a base-10 number, 0-255
+* a = #
+	mx %10
+
+
+	ldx #0
+
+:100
+	cmp #100
+	bcc :10x
+	inx
+*	sec
+	sbc #100
+	bra :100
+
+:10x
+	cpx #0
+	beq :10
+
+	pha
+	txa
+*	clc
+*	adc #"0"
+	ora #"0"
+	sta |$0,y
+	iny
+	pla
+	ldx #0
+
+:10
+	cmp #10
+	bcc :1x
+	inx
+	sbc #10
+	bra :10
+
+:1x
+	cpx #0
+	beq :1
+	pha
+	txa
+*	clc
+*	adc #"0"
+	ora #"0"
+	sta |$0,y
+	iny
+	pla
+
+:1
+*	clc
+*	adc #"0"
+	ora #"0"
+	sta |$0,y
+	iny
+	rts
+
+print_binary
+	mx %10
+*	pha
+*	lda #"%"
+*	sta |$0,y
+*	iny
+*	pla
+	lup 8
+	asl
+	pha
+	lda #0
+	adc #"0"
+	sta |$0,y
+	iny
+	pla
+	--^
+	rts
+
+print_hex
+	mx %10
+
+	xba
+	lda #0
+	xba
+	pha
+	lsr
+	lsr
+	lsr
+	lsr
+	tax
+	lda hex,x
+	sta |$0,y
+	iny
+	pla
+	and #$0f
+	tax
+	lda hex,x
+	sta |$0,y
+	iny
+	rts
+
+
+hexdump_r
+*
+* $1e00 buffer
+*
+
+	mx %00
+
+	lda DPAGE+read_q_tail
+	sec
+	sbc #8*16
+	and #$00ff
+	ora #$1e00
+	jmp hexdump_common
+
+
+hexdump_w
+*
+* $1d00 buffer
+*
+	mx %00
+
+
+	lda DPAGE+write_q_tail
+	sec
+	sbc #8*16
+	and #$00ff
+	ora #$1d00
+	jmp hexdump_common
+
+
+hexdump_common
+*
+* a = address to start.
+
+
+
+:screen	equ 0
+:screen2	equ 2
+*:offset	equ 4
+:ptr	equ 6
+:count	equ 8
+:row	equ 10
+:c	equ 12
+
+	mx %00
+	debug hexdump
+
+
+	php
+	sta :ptr
+	lda #0
+
+*	stz :offset
+
+	sep #$20
+
+	ldx #4*2
+	stx :row
+
+
+:one_row
+
+	ldx :row
+	ldy text,x
+	sty :screen
+	sty :screen2
+
+
+
+	lda #8
+	sta :count
+
+:one_byte
+
+	lda (:ptr)
+	inc :ptr
+
+	sta :c
+	lsr
+	lsr
+	lsr
+	lsr
+	tax
+	lda hex,x
+	ldy :screen
+	sta |$04,y
+	iny
+	lda :c
+	and #$0f
+	tax
+	lda hex,x
+	sta |$04,y
+	iny
+	lda #" "
+	sta |$04,y
+	iny
+	sty :screen
+
+
+* ascii
+	ldx #"."
+	lda :c
+	cmp #$20
+	blt :dot
+	cmp #$80
+	bcs :dot
+	ora #$80
+	tax
+:dot
+	txa
+	ldy :screen2
+	sta |8*3+4,y
+	iny
+	sty :screen2
+
+
+	dec :count
+	bne :one_byte
+
+
+	ldx :row
+	inx
+	inx
+	stx :row
+	cpx #20*2
+	bcc :one_row
+
+	plp
+	rts
+
+
+hex	asc "0123456789abcdef"
+
+
+
+ssc_registers
+	debug ssc_registers
+*
+* print SSC read registers.  read reg 8 (incoming data byte) is skipped.
+*
+*
+
+*SCCBREG		equ $c038
+*SCCAREG		equ $c039
+*SCCBDATA	equ $c03a
+*SCCADATA	equ $c03b
+
+* read everything at once.
+
+	php
+	sep #$34 ; short m/x, ints off
+	lda #0
+	xba
+*	sei
+	ldx #0
+	lda SCCAREG ; sync
+	lda SCCBREG ; sync
+
+	stx SCCAREG
+	lda SCCAREG
+	sta ssc_data+0
+	stx SCCBREG
+	lda SCCBREG
+	sta ssc_data+1
+
+	inx ;1
+
+	stx SCCAREG
+	lda SCCAREG
+	sta ssc_data+2
+	stx SCCBREG
+	lda SCCBREG
+	sta ssc_data+3
+
+	inx ;2
+
+	stx SCCAREG
+	lda SCCAREG
+	sta ssc_data+4
+	stx SCCBREG
+	lda SCCBREG
+	sta ssc_data+5
+
+	inx ;3
+
+	stx SCCAREG
+	lda SCCAREG
+	sta ssc_data+6
+	stx SCCBREG
+	lda SCCBREG
+	sta ssc_data+7
+
+
+	ldx #10 ; 10
+
+	stx SCCAREG
+	lda SCCAREG
+	sta ssc_data+8
+	stx SCCBREG
+	lda SCCBREG
+	sta ssc_data+9
+
+
+	ldx #12 ; 12
+
+	stx SCCAREG
+	lda SCCAREG
+	sta ssc_data+10
+	stx SCCBREG
+	lda SCCBREG
+	sta ssc_data+11
+
+	inx ; 13
+
+	stx SCCAREG
+	lda SCCAREG
+	sta ssc_data+12
+	stx SCCBREG
+	lda SCCBREG
+	sta ssc_data+13
+
+	ldx #15 ; 15
+
+	stx SCCAREG
+	lda SCCAREG
+	sta ssc_data+14
+	stx SCCBREG
+	lda SCCBREG
+	sta ssc_data+15
+
+
+	cli
+	rep #$10 ; long x
+	mx %10
+	jsr rr0
+	jsr rr1
+	jsr rr2
+	jsr rr3 ; only exists in channel A.
+	jsr rr10
+	jsr rr12 ; baud low
+*	jsr rr13 ; baud high
+	jsr rr15
+	plp
+	rts
+
+ssc_data	ds 16
+
+rr0
+	mx %10
+	ldy #line_5+4
+	ldx #:str
+	jsr print_xy_str
+	lda ssc_data+0
+	jsr print_binary
+	iny
+	iny
+	lda ssc_data+1
+	jmp print_binary
+
+:str	asc "RR 0:  ",00
+
+rr1
+	mx %10
+	ldy #line_6+4
+	ldx #:str
+	jsr print_xy_str
+	lda ssc_data+2
+	jsr print_binary
+	iny
+	iny
+	lda ssc_data+3
+	jmp print_binary
+
+:str	asc "RR 1:  ",00
+
+rr2
+	mx %10
+	ldy #line_7+4
+	ldx #:str
+	jsr print_xy_str
+	lda ssc_data+4
+	jsr print_binary
+	iny
+	iny
+	lda ssc_data+5
+	jmp print_binary
+
+:str	asc "RR 2:  ",00
+
+rr3
+	mx %10
+	ldy #line_8+4
+	ldx #:str
+	jsr print_xy_str
+	lda ssc_data+6
+	jsr print_binary
+	iny
+	iny
+	lda ssc_data+7
+	jmp print_binary
+
+:str	asc "RR 3:  ",00
+
+rr10
+	mx %10
+	ldy #line_9+4
+	ldx #:str
+	jsr print_xy_str
+	lda ssc_data+8
+	jsr print_binary
+	iny
+	iny
+	lda ssc_data+9
+	jmp print_binary
+
+:str	asc "RR 10: ",00
+
+* 12/13 are baud
+
+rr12
+	mx %10
+	ldy #line_10+4
+	ldx #:str
+	jsr print_xy_str
+
+	iny
+	iny
+	iny
+	iny
+
+	lda ssc_data+12
+	jsr print_hex
+	lda ssc_data+10
+	jsr print_hex
+
+	iny
+	iny
+	iny
+	iny
+	iny
+	iny
+
+	lda ssc_data+13
+	jsr print_hex
+	lda ssc_data+11
+	jmp print_hex
+
+
+:str	asc "RR 12: ",00
+
+
+rr15
+	mx %10
+	ldy #line_11+4
+	ldx #:str
+	jsr print_xy_str
+
+	lda ssc_data+14
+	jsr print_binary
+	iny
+	iny
+	lda ssc_data+15
+	jmp print_binary
+
+:str	asc "RR 15: ",00
+
+
+
+
+
 text
 	dw $0400
 	dw $0480
@@ -215,4 +1019,30 @@ text
 
 
 
+line_0	equ $0400
+line_1	equ $0480
+line_2	equ $0500
+line_3	equ $0580
+line_4	equ $0600
+line_5	equ $0680
+line_6	equ $0700
+line_7	equ $0780
+line_8	equ $0428
+line_9	equ $04a8
+line_10	equ $0528
+line_11	equ $05a8
+line_12	equ $0628
+line_13	equ $06a8
+line_14	equ $0728
+line_15	equ $07a8
+line_16	equ $0450
+line_17	equ $04d0
+line_18	equ $0550
+line_19	equ $05d0
+line_20	equ $0650
+line_21	equ $06d0
+line_22	equ $0750
+line_23	equ $07d0
+
+
 	sav vt100.cda.L

vt100.csi.S

@@ -16,8 +16,9 @@
 	ext recalc_cursor,recalc_cursor_x,recalc_cursor_y
 	ext erase_line_0,erase_line_1,erase_line_2
 	ext erase_screen_0,erase_screen_1,erase_screen_2
+	ext update_sgr
 
-	ext write_modem
+	ext write_modem,write_modem_str
 
 
 vt100_csi ent
@@ -261,7 +262,7 @@ vt100_csi_2 ent
 	dw :rts		; u
 	dw :rts		; v
 	dw :rts		; w
-	dw :rts		; x
+	dw csi_x	; x
 	dw csi_y	; y
 
 :modifier
@@ -353,7 +354,7 @@ mode_common
 	dw :rts ; error
 	dw mode_DECCKM
 	dw mode_DECANM
-	dw :rts ; DECCOLM
+	dw mode_DECCOLM ; DECCOLM
 	dw :rts ; DECSCLM
 	dw mode_DECSCNM
 	dw mode_DECOM
@@ -395,10 +396,33 @@ mode_DECANM
 :rts	rts
 
 
-*mode_DECCOLM
+mode_DECCOLM
-*	sty DECCOLM
+* 80/132 mode.
-*	rts
+* vt102 guide states:
+* NOTE: When you change the number of columns per line, the screen is erased. 
+* This also sets the scrolling region for full screen (24 lines).
+*
+* based on testing, this always clears the screen and resets x/y, regardless of current mode.
+*
 
+	bit pmod
+	bpl :rts
+
+	sty DECCOLM
+
+	lda #0
+	sta DECTM
+	lda #23
+	sta DECBM
+	stz x
+	stz y
+
+	phy
+	jsr recalc_cursor
+	jsr erase_screen_2
+	ply
+
+:rts	rts
 
 mode_DECSCNM
 	bit pmod
@@ -472,12 +496,8 @@ csi_m
 	cpx pcount
 	blt :loop
 
-* now update - bit 7 indicates inverse.
+	jmp update_sgr
-	lda SGR
-	and #$80
-	sta draw_inverse
 
-:rts	rts
 
 
 :and	db $00,$ff,$ff,$ff,$ff,$ff,$ff,$ff
@@ -679,6 +699,7 @@ csi_H ; direct cursor addressing
 	jmp recalc_cursor
 
 csi_r ; scrolling region
+	debug csi_r
 * based on testing
 * esc [ n r (no second parmeter) is equivalent to esc [ n ; 24 r
 * esc [ r sets scrolling region to 1 ; 24 ( in accordance with above )
@@ -703,11 +724,11 @@ csi_r ; scrolling region
 :check
 * 23 max
 	ldx parms+0
-	cmp #23+1
+	cpx #23+1
 	bge :rts
 
 	ldx parms+1
-	cmp #23+1
+	cpx #23+1
 	bge :rts
 
 
@@ -786,12 +807,19 @@ csi_n  ; status report
 	lda #'n'
 	jmp write_modem
 :cpr ; cursor report
-* TODO - verify and support DECOM
+* returned y is in terms of DECOM.
 	lda #ESC
 	jsr write_modem
 	lda #'['
+	jsr write_modem
+
 	lda y
-	inc
+	bit DECOM
+	bpl :y
+	sec
+	sbc DECTM
+
+:y	inc
 	jsr write_digit
 	lda #';'
 	jsr write_modem
@@ -827,23 +855,45 @@ write_digit
 :table	db 0,10,20,30,40,50,60,70,80
 
 csi_c  ; what are you?
-	lda #ESC
+* DA - Device Attributes
-	jsr write_modem
+
-	lda #'['
+	mx %11
-	jsr write_modem
+
-	lda #'?'
+	php
-	jsr write_modem
+	rep #$10 ; long x/y
-	lda #'1'
+	ldy #:response
-	jsr write_modem
+	jsr write_modem_str
-	lda #'?'
+	plp
-	jsr write_modem
+	rts
-	lda #'0'
+
-	jsr write_modem
+:response asc 1b,'[?1;0c',00 ; No options.
-	lda #'c'
-	jmp write_modem
 
 csi_y  ; invoke confidence test
 * ??? 
 	rts
 
+
+
+csi_x ; request terminal parameters
+* DECREQTPARM – Request Terminal Parameters
+
+	mx %11
+
+	lda parms
+	cmp #2
+	bcs :rts
+	inc
+	inc
+	ora #'0'
+	sta :response+2
+
+	php
+	rep #$10 ; long x/y
+	ldy #:response
+	jsr write_modem_str
+	plp
+:rts	rts
+
+:response asc 1b,'[x;1;1;112;112;1;0x',00 ; no parity, 8-bits, 9600/9600, 16x multiplier, no stp flags.
+
 	sav vt100.csi.L

vt100.ctrl.S

@@ -109,8 +109,11 @@ xoff
 	rts
 can
 sub
+	ext draw_char_raw
 * cancel esc sequence and display error character
 	stz state
+	lda #$57 ; mouse text block
+	jmp draw_char_raw
 	rts
 
 esc

vt100.esc.S

@@ -11,6 +11,8 @@
 
 	ext recalc_cursor,recalc_cursor_x,recalc_cursor_y
 	ext scroll_up,scroll_down
+	ext reset
+	ext update_sgr
 
 vt100_esc ent
 * #[()=>cH78DEM
@@ -133,21 +135,29 @@ vt100_esc ent
 
 
 esc_7 ; save cursor position, graphic rendition, and character set.
-
+* based on testing, DECOM is also saved/restored.
 	lda x
 	sta saved_x
 	lda y
 	sta saved_y
+	lda DECOM
+	sta saved_decom
+	lda SGR
+	sta saved_sgr
 
 	rts
 esc_8 ; restore cursor position, graphic rendition, and character set.
 
-* TODO - how does this interact with DECOM?
-
 	lda saved_x
 	sta x
 	lda saved_y
 	sta y
+	lda saved_decom
+	sta DECOM
+	lda saved_sgr
+	sta SGR
+
+	jsr update_sgr
 	jmp recalc_cursor
 
 esc_eq ; enter alternate keypad mode
@@ -206,8 +216,8 @@ esc_M ; reverse index
 :rts	rts
 
 
-esc_c ; reset terminal.
+esc_c ; TODO - reset terminal.
-	rts
+	jmp reset
 
 
 vt100_esc_bad ent
@@ -294,6 +304,7 @@ vt100_esc_rparen ent
 * SI, aka Control-O aka 0x0f set the G0 char set
 
 * not currently supported.
+* TODO - mouse text support?
 
 	ldx #st_vt100
 	stx state

vt100.key.S

@@ -4,13 +4,16 @@
 	xc
 	xc
 
+	tbx on
+
 	use vt.equ
 	use apple2gs.equ
 	use debug
 
 	mx %11
 
-	ext dispatch
+*	ext dispatch
+	ext write_modem
 
 
 kmShift		equ %0000_0001
@@ -22,22 +25,58 @@ kmUpdateMod	equ %0010_0000
 kmOption	equ %0100_0000
 kmCommand	equ %1000_0000
 
+
+*
+* The vt100 has a delete key and a backspace key.
+* delete sends 0x7f.  backspace sends 0x08.
+* stty is general set so 0x7f is the erase character.
+* termcaps generally claim 0x08 is the backspace character.
+*
+* emacs, by default, thinks 0x08 ( ^H ) means you want help.
+*
+* so, backspace will send 0x7f.  control-H or command-backspace
+* will send 0x08. 
+
+*
+* TODO - keys
+* command-L -> local/online mode?
+* command-Q -> quit
+* command-K -> clear screen?
+* command-R -> reset settings
+*
+
+
+dispatch
+	jmp write_modem
+
 keypress ent
 	debug keypress
 	lda KBD
 	bmi :key
-	rts
+:rts	rts
 :key
 	and #$7f
 	sta key
 	lda KEYMOD
 	sta mod
 	sta KEYSTROBE
+
+* if DECARM is clear, skip repeat characters.
+*
+* a REAL vt100 will never auto-repeat ESC, TAB, RETURN, or if Control is also pressed. 
+*
+	bit DECARM
+	bpl :arm
+	bit #kmRepeat
+	bne :rts
+:arm
+
+
 	bit #kmOption!kmCommand
-	bne :command
+	bne command
 
 	bit #kmKeypad
-	bne keypad
+	jne keypad
 	bit #kmControl
 	bne :ctrl
 
@@ -55,22 +94,35 @@ keypress ent
 
 :ctrl
 	lda key
+	and #$1f ; control-space should generate 0, not $20.
 	bra :send
 
 :notctrl
-	cmp #$7f ; delete - special case 
+*	cmp #$7f ; delete - special case 
-	bne :send
+*	bne :send
-	lda #$08
+*	lda #$08
 :send	jmp dispatch
 
-:command ; or option
+command ; or option
-	rts
 
-
+* apple-return -> linefeed
-keypad
+* apple-backspace -> delete
-* todo - keypad enters honors LNM?
+	
 
 	lda key
+	cmp #$7f
+	beq :bs
+	cmp #$0d
+	beq :lf
+
+	cmp #'a'
+	bcc :0
+	cmp #'z'+1
+	bcs :0
+
+	and #$df ; ~ $20
+
+:0
 	cmp #:MIN
 	blt :rts
 	cmp #:MAX+1
@@ -83,6 +135,104 @@ keypad
 
 :rts	rts
 
+
+:bs	lda #$08
+	jmp dispatch ; 
+:lf	lda #$0a
+	jmp dispatch
+
+	ext enable_modem,disable_modem
+:local
+	bit LOCAL
+	bmi :online
+	lda #$80
+	sta LOCAL
+	jmp disable_modem
+
+:online
+	stz LOCAL
+	jmp enable_modem
+
+:quit
+	ext quit
+	jmp quit
+	rts
+
+:reset
+* TODO
+	rts
+
+:clear
+* TODO
+	rts
+
+
+:MIN	equ 49
+:MAX	equ 82
+
+:table
+	dw pf1		; 1
+	dw pf2		; 2
+	dw pf3		; 3
+	dw pf4		; 4
+	dw :rts		; 5
+	dw :rts		; 6
+	dw :rts		; 7
+	dw :rts		; 8
+	dw :rts		; 9
+	dw :rts		; :
+	dw :rts		; ;
+	dw :rts		; <
+	dw :rts		; =
+	dw :rts		; >
+	dw :rts		; ?
+	dw :rts		; @
+	dw :rts		; A
+	dw :rts		; B
+	dw :rts		; C
+	dw :rts		; D
+	dw :rts		; E
+	dw :rts		; F
+	dw :rts		; G
+	dw :rts		; H
+	dw :rts		; I
+	dw :rts		; J
+	dw :clear	; K
+	dw :local	; L
+	dw :rts		; M
+	dw :rts		; N
+	dw :rts		; O
+	dw :rts		; P
+	dw :quit	; Q
+	dw :reset	; R
+
+
+
+keypad
+
+	lda key
+	cmp #:MIN
+	blt :rts
+	cmp #:MAX+1
+	bcs :other
+	sec
+	sbc #:MIN
+	asl
+	tax
+	jmp (:table,x)
+
+:other
+
+* keypad delete key ($75 aka 'u') will send as backspace ($08)
+*
+	cmp #'u'
+	bne :rts
+	lda #$08
+	jmp dispatch
+	
+
+:rts	rts
+
 :MIN	equ 13
 :MAX	equ 61
 :table
@@ -118,7 +268,7 @@ keypad
 	dw pf4		; *
 	dw comma	; +
 	dw :rts		; ,
-	dw dash	; -
+	dw dash		; -
 	dw dot		; .
 	dw pf3		; / PF3 -> ESC R
 	dw digit	; 0
@@ -131,9 +281,9 @@ keypad
 	dw digit	; 7
 	dw digit	; 8
 	dw digit	; 9
-	dw $0		; :
+	dw :rts		; :
-	dw $0		; ;
+	dw :rts		; ;
-	dw $0		; <
+	dw :rts		; <
 	dw pf2		; = PF2 -> ESC Q
 
 
@@ -195,6 +345,7 @@ digit
 	lda #'?'
 	jsr dispatch
 	lda key
+	ora #$40
 	jmp dispatch
 
 

vt100.main.S

@@ -4,6 +4,8 @@
 	xc
 	xc
 
+	tbx on ; qasm
+
 	mx %11
 	use vt.equ
 	use apple2gs.equ
@@ -11,13 +13,14 @@
 
 	ext scroll_down
 	ext recalc_cursor,recalc_cursor_x,recalc_cursor_y
-	ext write_modem,read_modem,init_modem,modem_vector
+	ext modem_io,modem_vector,reset_modem_buffer
+	ext modem_startup,modem_shutdown
 	ext keypress
 	ext disable_cursor,enable_cursor,cursor_vector
 	ext erase_screen,fill_screen
 	ext init_tabs
 	ext init_audio
-	ext init_cda
+	ext cda_startup,cda_shutdown
 
 main	debug main
 
@@ -25,6 +28,9 @@ main	debug main
 	xce
 	cli
 
+	pea DPAGE
+	pld
+
 	jsr init
 	jsr enable_cursor
 
@@ -34,23 +40,23 @@ main	debug main
 	stz SCANINT ; reset 1-sec interrupt
 
 
-
 loop
-	bit LOCAL
+	jsr keypress ; check for a keypress, write data to out buffer.
-	bmi :kb
+	jsr modem_io ; 
-	jsr read_modem
+	bcc :nope
-	bcc :kb
 	pha
 	jsr disable_cursor
 	pla
 	jsr vt100
-:kb	
+	bra loop
-	jsr keypress
+
+:nope	; no modem data, re-enable the cursor.
 	jsr enable_cursor
 	bra loop
 
 init
 	mx %11
+
 	lda #" "
 	jsr fill_screen ; erase first to prevent flash if going 40->80 columns.
 
@@ -59,6 +65,9 @@ init
 	sta SETALTCHAR
 	rep #$30
 
+	jsr init_mem
+
+
 	ldx #254
 :zloop	stz 0,x
 	dex
@@ -103,30 +112,196 @@ init
 	sta DECBM
 	lda #$80
 *	sta LOCAL
-	sta DECANM
+	sta DECANM ; ANSI (vt100) on
+	sta DECARM ; key repeat on
 
 *	lda #st_vt52
 	lda #st_vt100
 	sta state
 
 *	jsr erase_screen
-	jsr init_modem
+	jsr modem_startup
 	jsr init_tabs
 	jsr init_audio
-	jsr init_cda
+	jsr cda_startup
 	rts
 
 
-dispatch ent
+MasterID	dw 0
-	mx %11
+init_mem
-* a = character to xmit
+*
-	bit LOCAL
+* see prodos technote #27
-	bmi :local
+*
-	jmp write_modem
+* _InstallCDA uses the memory manager ; otherwise I wouldn't bother
-:local
+* This is here to prevent MM from stomping on our memory.
+*
+
+	mx %00
+
+	stz MasterID
+	_TLStartUp
 	pha
-	jsr disable_cursor
+	_MMStartUp
 	pla
+	bcs :p8
+	rts
+:p8
+	_MTStartUp
+	pea #0
+	pea #$1000
+	_GetNewID
+	pla
+	sta MasterID
+
+* bank 0
+	pha
+	pha
+	pea #$0000
+	pea #$b800
+	lda MasterID
+	pha
+	pea #$c013
+	pea #0000
+	pea #0800
+	_NewHandle
+	pla
+	pla
+
+* bank 1
+	pha
+	pha
+	pea #$0000
+	pea #$b800
+	lda MasterID
+	pha
+	pea #$c013
+	pea #$0001
+	pea #$0800
+	_NewHandle
+	pla
+	pla
+
+	rts
+
+
+reset	ent
+	mx %11
+	php
+
+* disable 1-sec interrupt...
+
+	lda #4
+	trb VGCINT ; disable 1-sec interrupt.
+	stz SCANINT ; reset 1-sec interrupt
+
+
+	lda #" "
+	jsr fill_screen ; erase first to prevent flash if going 40->80 columns.
+
+	rep #$30
+
+	ldx #254
+:zloop	stz 0,x
+	dex
+	dex
+	bpl :zloop
+
+	lda #$0400
+	sta cursor_base
+	lda #$01
+	sta cursor_base+2
+
+	lda #"  " ; 16-bit
+	sta erase_char
+
+
+	lda #$0080
+	sta cursor_state
+
+	lda #0 ; clear high byte
+
+	sep #$30
+
+	lda #"_"
+	sta cursor_char
+
+
+	lda #23
+	sta DECBM
+	lda #$80
+	sta DECANM ; ansi mode
+	sta DECARM ; key repeat on
+
+	lda #st_vt100
+	sta state
+
+	jsr init_tabs
+*	jsr enable_cursor
+
+	jsr reset_modem_buffer
+
+	lda #4
+	tsb VGCINT ; enable 1-sec interrupt.
+	stz SCANINT ; reset 1-sec interrupt
+
+	plp
+	rts
+
+
+quit	ent
+
+* need to disable modem interrupts
+
+
+	sep #$30
+	lda #4
+	trb VGCINT ; disable 1-sec interrupt.
+	stz SCANINT ; reset 1-sec interrupt
+
+	jsr modem_shutdown
+
+	rep #$30
+
+	jsr cda_shutdown
+
+	lda MasterID
+	beq :e
+
+	pha
+	pha
+	_DisposeAll
+	_DeleteID
+
+:e
+	pea #0
+	pld
+
+	sec
+	xce
+	mx %00
+	inc $3f4 ; invalidate power-up bit 
+	jsr $bf00
+	db $65
+	dw :parms
+	brk $ea
+
+:parms	db 4
+	db 0
+	dw 0
+	db 0
+	dw 0
+
+
+*dispatch ent
+*	mx %11
+** a = character to xmit
+*	bit LOCAL
+*	bmi :local
+*	jmp write_modem
+*:local
+*	pha
+*	jsr disable_cursor
+*	pla
 
 * fall through
 
@@ -149,7 +324,7 @@ vt100
 	ext vt100_esc,vt100_csi,vt100_csi_2
 	ext vt100_esc_pound,vt100_esc_lparen,vt100_esc_rparen
 	ext vt100_esc_bad,vt100_csi_bad
-	ext draw_char
+	ext draw_char,draw_char_raw
 
 	dw draw_char
 	dw vt52_esc
@@ -225,7 +400,16 @@ ctrl_18
 ctrl_1a
 * vt100 - abort current escape sequence
 * and display error character.
-* TODO - display error character (mouse text)
+*
+* based on testing, this applies to vt52 and vt100;
+* cancel character is drawn regardless of current state.
+
+	lda x
+	and #$1
+	ora #$56 ; $56 or $57
+*	lda #$57
+	jsr draw_char_raw
+
 	bit DECANM
 	bpl :vt52
 	lda #st_vt100

vt100.modem.S

@@ -6,7 +6,8 @@
 
 	mx %11
 	cas se
-*	use vt.equ
+	use vt.equ
+	use debug
 
 SCCBREG		equ $c038
 SCCAREG		equ $c039
@@ -29,143 +30,132 @@ SerFlag		equ $e10104 ;
 *
 * see IIgs TN #18 - Do-It-Yourself SCC Access
 
-init_modem ent
+modem_startup ent
+enable_modem ent
 *	sep #$30
 
+	php
+	sei
 
-	stz q_head
+	stz read_q_head
-	stz q_tail
+	stz read_q_tail
-
+	stz write_q_head
-* reset channel B (modem port)
+	stz write_q_tail
-	ldx #9
-	lda #%01_0_1_0_0_0_1
-	stx SCCBREG
-	sta SCCBREG
-	nop
-	nop
-
-* x16 clock mode, 1 stop bit, no parity	
-	ldx #4
-	lda #%01_00_01_0_0
-	stx SCCBREG
-	sta SCCBREG
-
-* 8 bits/char, rx disabled.
-	ldx #3
-	lda #%11_0_0_0_0_0_0
-	stx SCCBREG
-	sta SCCBREG
-
-* 8 data bits, RTS
-	ldx #5
-	lda #%0_11_0_0_0_1_0
-	stx SCCBREG
-	sta SCCBREG
-
-* bit 7 = 1 for printer port, 0 for modem port.
-* 5/6 = (%10) rcv clock = br output
-* 4/3 = (%10) tx clock = br output
-
-	ldx #11
-	lda #%0_10_10_0_00
-	stx SCCBREG
-	sta SCCBREG
-
-* 9600 baud
-	ldx #12
-	lda #10
-	stx SCCBREG
-	sta SCCBREG
-
-* 9600 baud
-	ldx #13
-	lda #0
-	stx SCCBREG
-	sta SCCBREG
 
 
-* disable baud rate generator
+* zero out the buffer [for CDA debugger]
-	ldx #14
-	lda #0
-	stx SCCBREG
-	sta SCCBREG
-
-* enable baud rate generator
-	ldx #14
-	lda #%000_0_0_0_0_1
-	stx SCCBREG
-	sta SCCBREG
-
-
-
-* 8 bits/char, rx enabled.
-	ldx #3
-	lda #%11_0_0_0_0_0_1
-	stx SCCBREG
-	sta SCCBREG
-
-
-* 8 data bits, tx enabled, RTS
-	ldx #5
-	lda #%0_11_0_1_0_1_0
-	stx SCCBREG
-	sta SCCBREG
-
-* disable interrupts
-	ldx #15
-	lda #0
-	stx SCCBREG
-	sta SCCBREG
-
-* reset ext/status interrupts
 	ldx #0
-	lda #%00_010_0_00
+]loop	stz read_buffer,x
-	stx SCCBREG
+	inx
+	bne ]loop
+
+
+	lda SCCBREG ; sync access
+	ldx #0
+
+]loop
+	lda :table,x
+	bmi :done
 	sta SCCBREG
-
+	inx
-* enable interrupts
+	lda :table,x
-	ldx #1
-*	lda #0
-	lda #%0_0_0_10_0_0_0 ; inr on rx or special condition.
-	stx SCCBREG
 	sta SCCBREG
-
+	inx
-* reset ch b ptr to 0?
+	bra ]loop
-	lda SCCBREG
+:done
-
-
-* no vector, master interrupts enabled
-	ldx #9
-	lda #%00_0_0_1_0_1_0
-	stx SCCBREG
-	sta SCCBREG
-	nop
-	nop
-
 
 * adjust SerFlag so serial IRQs will be handled.
 	lda >SerFlag
 	ora #%00_000_111 ; channel B interrupts.
 	sta >SerFlag
 
+	plp
 	rts
 
-write_modem ent
+:table  ; register, value
+*	db 9,%01_0_1_0_0_0_1 ; reset channel B (modem port) - handled @ startup.
+	db 4,%01_00_01_0_0 ; x16 clock, 1 stop bit, no parity
+	db 3,%11_0_0_0_0_0_0 ; 8 bits, rx disabled
+	db 5,%0_11_0_0_0_1_0 ; 8 bits, RTS
+	db 11,%0_10_10_0_00 ; modem port, rcv/tx clock = br
+	db 12,10 ; 9600 baud (low)
+	db 13,0 ; 9600 baud (high)
+	db 14,0 ; disable baud rate generator
+	db 14,%000_0_0_0_0_1 ; enable baud rate generator
+	db 3,%11_0_0_0_0_0_1 ; 8 bits, rx enabled
+	db 5,%0_11_0_1_0_1_0 ; 8 bits, tx enabled, RTS
+	db 15,0 ; disable external interrupts
+	db 0,%00_010_0_00 ; reset ext/status interrupts
+	db 1,%0_0_0_10_0_0_0 ; interrupts on rx or special condition
+	db 9,%00_0_0_1_0_1_0 ; master interrupts enabled.
+	db -1,-1
+
+
+disable_modem ent
+* local mode
+	mx %11
+	php
+	sei
+
+	lda SCCBREG ; sync access
+	lda #9
+	sta SCCBREG
+	lda #%01_0_1_0_0_0_1 ; reset channel B.
+	sta SCCBREG
+
+	stz read_q_head
+	stz read_q_tail
+	stz write_q_head
+	stz write_q_tail
+
+	plp
+	rts
+
+
+modem_shutdown	ent
+
+	mx %11
+	php
+	sei
+
+	lda SCCBREG ; sync access
+	lda #9
+	sta SCCBREG
+	lda #%01_0_1_0_0_0_1 ; reset channel B.
+	sta SCCBREG
+
+
+	lda >SerFlag
+	and #%11_111_000 ; channel B interrupts.
+	sta >SerFlag
+
+	plp
+	rts
+
+
+write_modem_sync ent
 	mx %11
 * a: byte to send
 	tay ; save
 *	ldx #0
+	php
+
 
 :mask	= %0010_0100  ; tx buffer empty, clear to send
-:wait	stz SCCBREG
+:wait	
+	cli ; guard scc register access.
+	sei
+	stz SCCBREG
 	lda SCCBREG
 	and #:mask
 	cmp #:mask
 	bne :wait
 
 	sty SCCBDATA
+	plp
 	rts
 
+
 read_modem_sync ent
 * c set if data read
 * v set if overrun
@@ -183,9 +173,7 @@ read_modem_sync ent
 	lda SCCBREG
 	and #%0010_0000
 	beq :ok
-* indicate overrun...
+
-	lda #"x"
-	sta |$07d0+20
 * clear the overrun
 	lda #$30 ; reg0, error reset.
 	sta SCCBREG
@@ -198,17 +186,14 @@ read_modem_sync ent
 	lda SCCBDATA
 
 * debugging...
-	ldx :debug
+
-	sta $1e00,x
-	inc :debug
 
 	sec
 :rts	rts
 
 
-:debug	ds 2
+write_buffer equ $1d00
-
+read_buffer equ $1e00
-buffer equ $1d00
 
 modem_vector	ent
 	jml modem_int
@@ -219,14 +204,21 @@ modem_int
 * a/x/y don't need to be preserved.
 * return carry clear if handled, carry set if not.
 
+* doesn't access direct page.
 
 * check/clear overrun?
+
+*
+* n.b. - vt100 would drop $00 and $7f characters here - I drop them later.
+*
+
 	mx %11
 
 	phb
 	phk
 	plb
 
+	lda SCCBREG ; sync
 	stz SCCBREG
 	lda SCCBREG
 	and #%0000_0001 ; rx ready.
@@ -234,9 +226,9 @@ modem_int
 
 :read
 	lda SCCBDATA
-	ldx q_tail
+	ldx DPAGE+read_q_head
-	sta buffer,x
+	sta read_buffer,x
-	inc q_tail
+	inc DPAGE+read_q_head
 
 * more?
 	stz SCCBREG
@@ -263,6 +255,130 @@ modem_int
 	plb
 	rtl
 
+
+
+modem_io ent
+	debug modem_io
+
+	mx %11
+	php
+	sei
+	bit LOCAL
+	bmi :local
+
+:write
+* send any outbound data...
+
+:mask	= %0010_0100  ; tx buffer empty, clear to send
+	ldx write_q_tail
+	cpx write_q_head
+	beq :read
+
+	lda SCCBREG ; sync
+	stz SCCBREG
+	lda SCCBREG
+	and #:mask
+	cmp #:mask
+	bne :read
+
+*	ldx write_q_tail
+	lda write_buffer,x
+	sta SCCBDATA
+	inc write_q_tail
+:read
+	ldx read_q_tail
+	cpx read_q_head
+	beq :nope
+	lda read_buffer,x
+	inc read_q_tail
+
+* $00 and $7f dropped here.
+	and #$7f
+	beq :read 
+	cmp #$7f
+	beq :read
+
+	plp
+	sec
+	rts
+
+:nope
+	plp
+	clc
+	rts
+	
+
+:local
+	ldx write_q_tail
+	cpx write_q_head
+	beq :nope
+	lda write_buffer,x
+	inc write_q_tail
+	plp
+	sec
+	rts
+
+
+
+write_modem ent
+write_modem_async ent
+
+	mx %11
+	php
+	sei
+
+*	bit LOCAL
+*	bmi :local
+
+	ldx write_q_head
+	sta write_buffer,x
+	inc write_q_head
+	plp
+	rts
+*:local
+*	ldx read_q_head
+*	sta read_buffer,x
+*	inc read_q_head
+*	plp
+*	rts
+
+
+write_modem_str ent
+
+; y = address of string (0-terminated)
+; inc write_q_head vs inx
+; because it wraps at $ff
+
+	mx %10
+	php
+	sei
+*	bit LOCAL
+*	bmi :local
+
+:loop	lda |$0000,y
+	beq :fini
+	ldx write_q_head
+	sta write_buffer,x
+	inc write_q_head
+	iny
+	bra :loop
+
+*:local	lda |$0000,y
+*	beq :fini
+*	ldx read_q_head
+*	sta read_buffer,x
+*	inc read_q_head
+*	iny
+*	bra :local
+
+
+:fini
+	plp
+	rts
+
+
+
+
 read_modem ent
 read_modem_async ent
 
@@ -270,12 +386,12 @@ read_modem_async ent
 
 	php
 	sei
-	ldx q_head
+	ldx read_q_tail
-	cpx q_tail
+	cpx read_q_head
 	beq :nope
 
-	lda buffer,x
+	lda read_buffer,x
-	inc q_head
+	inc read_q_tail
 	plp
 	sec
 	rts
@@ -285,8 +401,19 @@ read_modem_async ent
 	clc
 	rts
 
-q_head	ds 2
+reset_modem_buffer ent
-q_tail	ds 2
+	mx %11
+	php
+	sei
+
+	stz read_q_head
+	stz read_q_tail
+	stz write_q_head
+	stz write_q_tail
+
+	plp
+	rts
+
 *buffer	ds 256
 
 	sav vt100.modem.L

vt100.screen.S

@@ -21,6 +21,17 @@
 * cursor_state - $80 = disabled, $40 = on
 
 
+update_sgr ent
+
+	stz draw_inverse
+	lda SGR
+	beq :rts
+	lda #$80
+	sta draw_inverse
+
+:rts	rts
+
+
 
 text
 	dw $0400
@@ -100,11 +111,20 @@ cursor_int
 
 	mx %11
 
+	phb
+	phd
+	phk
+	plb
+
+
 * check if CDA active.
 * $ff = inactive, $00 = active
 	lda >NumInts
 	bpl :rts
 
+	pea DPAGE
+	pld
+
 	ldy cursor_offset
 
 	lda cursor_state
@@ -125,6 +145,8 @@ cursor_int
 	sta [cursor_base],y
 
 :rts	stz SCANINT ; reset 1-sec interrupt
+	pld
+	plb
 	clc
 	rtl
 
@@ -225,16 +247,20 @@ draw_char ent
 	bpl :normal
 ; invert it.
 	cmp #$60 ; `, first lowercase
-	bge :draw ; nothing to do for lowercase
+	bge draw_char_raw ; nothing to do for lowercase
 	cmp #$40 ; @, first uppercase
-	bcc :draw ; nothing to do for special
+	bcc draw_char_raw ; nothing to do for special
 
 :uc	and #%10111111 ; ~ $40
-	bra :draw
+	bra draw_char_raw
 
 
 :normal	ora #$80
-:draw
+
+draw_char_raw ent
+* entry point for writing character to screen w/o processing it
+
+
 *	sta cursor_saved_char
 
 * with DECAWM, x = 79, will CR LF (with scroll) before drawing character.
@@ -269,8 +295,6 @@ draw_char ent
 	rts
 
 
-
-
 :wrap
 	stz x
 	ldy y
@@ -284,7 +308,7 @@ draw_char ent
 	jsr recalc_cursor
 	pla
 	sta [cursor_base] ; offset 0
-	rts
+	jmp advance_x
 
 :scroll
 	pha ; save
@@ -293,7 +317,7 @@ draw_char ent
 	jsr recalc_cursor_x
 	pla
 	sta [cursor_base] ; offset 0
-	rts	
+	jmp advance_x
 
 
 * erase screen commands are not affected by origin or scrolling region.