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https://github.com/ksherlock/itty-bitty-vtty.git
synced 2024-12-21 16:29:16 +00:00
at 2.6mhz, 9600baud, I was experiencing lost characters during line scroll or screen clear. To compensate, replace modem polling with asynchronous/interrupt-based code. Up to 256 bytes of modem data can be buffered.
Also, enable modem, vt100 as default Also, erase screen before switching to 80-column mode to prevent unsightly flashes.
This commit is contained in:
Kelvin Sherlock
parent
5a1f0f6ffc
commit
77ec62a091
@ -31,7 +31,11 @@ SGADDRH equ $c03f ; Sound GLU address reg high
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* interrupt vectors. JMP ABSLONG.
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IRQ1SEC equ $e10054
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IRQMOUSE equ $e10034
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IRQQTR equ $e10038
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IRQVBL equ $e10030
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IRQSND equ $e1002c
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IRQSCAN equ $e10028
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IRQSERIAL equ $e10024
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IRQATALK equ $e10020
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24
vt100.main.S
24
vt100.main.S
@ -11,9 +11,10 @@
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ext scroll_down
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ext recalc_cursor,recalc_cursor_x,recalc_cursor_y
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ext write_modem,read_modem,init_modem,keypress
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ext write_modem,read_modem,init_modem,modem_vector
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ext keypress
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ext disable_cursor,enable_cursor,cursor_vector
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ext erase_screen
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ext erase_screen,fill_screen
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ext init_tabs
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ext init_audio
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ext init_cda
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@ -49,6 +50,10 @@ loop
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bra loop
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init
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mx %11
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lda #" "
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jsr fill_screen ; erase first to prevent flash if going 40->80 columns.
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sta TXTSET
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sta SET80VID
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sta SETALTCHAR
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@ -72,11 +77,18 @@ init
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lda #$0080
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sta cursor_state
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sei
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lda cursor_vector
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stal IRQ1SEC
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lda cursor_vector+2
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stal IRQ1SEC+2
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lda modem_vector
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stal IRQSERIAL
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lda modem_vector+2
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stal IRQSERIAL+2
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cli
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lda #0 ; clear high byte
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@ -90,12 +102,14 @@ init
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lda #23
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sta DECBM
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lda #$80
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sta LOCAL
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* sta LOCAL
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sta DECANM
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lda #st_vt52
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* lda #st_vt52
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lda #st_vt100
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sta state
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jsr erase_screen
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* jsr erase_screen
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jsr init_modem
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jsr init_tabs
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jsr init_audio
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119
vt100.modem.S
119
vt100.modem.S
@ -14,6 +14,8 @@ SCCBDATA equ $c03a
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SCCADATA equ $c03b
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SerFlag equ $e10104 ;
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*
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* scc speed:
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*
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@ -23,10 +25,17 @@ SCCADATA equ $c03b
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* clock mode = 1x, 16x, 32x, or 64x (selected via write register 4 bits 6/7)
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* clock = 3.6864 MHz crystal (scc runs at 14.31818 / 4 = ~ 3.58 Mhz)
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* time constant = write register 12 (low) + 13 (high)
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*
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*
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* see IIgs TN #18 - Do-It-Yourself SCC Access
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init_modem ent
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* sep #$30
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stz q_head
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stz q_tail
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* reset channel B (modem port)
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ldx #9
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lda #%01_0_1_0_0_0_1
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@ -114,9 +123,10 @@ init_modem ent
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stx SCCBREG
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sta SCCBREG
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* disable interrupts
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* enable interrupts
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ldx #1
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lda #0
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* lda #0
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lda #%0_0_0_10_0_0_0 ; inr on rx or special condition.
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stx SCCBREG
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sta SCCBREG
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@ -124,15 +134,20 @@ init_modem ent
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lda SCCBREG
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* status, visible, master interrupts disabled
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* no vector, master interrupts enabled
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ldx #9
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lda #%00_0_1_0_0_0_1
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lda #%00_0_0_1_0_1_0
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stx SCCBREG
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sta SCCBREG
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nop
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nop
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* adjust SerFlag so serial IRQs will be handled.
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lda >SerFlag
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ora #%00_000_111 ; channel B interrupts.
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sta >SerFlag
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rts
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write_modem ent
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@ -151,7 +166,7 @@ write_modem ent
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sty SCCBDATA
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rts
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read_modem ent
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read_modem_sync ent
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* c set if data read
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* v set if overrun
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mx %11
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@ -168,6 +183,9 @@ read_modem ent
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lda SCCBREG
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and #%0010_0000
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beq :ok
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* indicate overrun...
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lda #"x"
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sta |$07d0+20
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* clear the overrun
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lda #$30 ; reg0, error reset.
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sta SCCBREG
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@ -178,8 +196,97 @@ read_modem ent
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* sta SCCBREG
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* lda SCCBREG
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lda SCCBDATA
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* debugging...
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ldx :debug
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sta $1e00,x
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inc :debug
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sec
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:rts rts
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:debug ds 2
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buffer equ $1d00
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modem_vector ent
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jml modem_int
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modem_int
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*
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* called in 8-bit native mode, interrupts disabled.
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* d = unknown
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* a/x/y don't need to be preserved.
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* return carry clear if handled, carry set if not.
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* check/clear overrun?
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mx %11
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phb
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phk
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plb
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stz SCCBREG
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lda SCCBREG
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and #%0000_0001 ; rx ready.
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beq :nope
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:read
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lda SCCBDATA
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ldx q_tail
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sta buffer,x
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inc q_tail
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* more?
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stz SCCBREG
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lda SCCBREG
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and #%0000_0001 ; rx ready.
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bne :read
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clc
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bra :finish
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:nope
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sec
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:finish
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* reset errors.
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lda #%00_110_000
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stz SCCBREG
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sta SCCBREG
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* reset highest ius
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lda #%00_111_000
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stz SCCBREG
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sta SCCBREG
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plb
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rtl
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read_modem ent
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read_modem_async ent
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mx %11
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php
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sei
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ldx q_head
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cpx q_tail
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beq :nope
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lda buffer,x
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inc q_head
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plp
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sec
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rts
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:nope
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plp
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clc
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rts
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q_head ds 2
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q_tail ds 2
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*buffer ds 256
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sav vt100.modem.L
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@ -82,6 +82,7 @@ esc_lt
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* (which we don't support anyhow.)
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lda #$80
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sta DECANM
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* stz MOUSETEXT
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lda #st_vt100
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sta state
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rts
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@ -176,10 +177,13 @@ esc_H ; cursor home
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esc_F ; enter graphics mode
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* lda #%0010
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* tsb mode
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lda #$80
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* tsb MOUSETEXT
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rts
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esc_G ; exit graphics mode
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* lda #%0010
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* trb mode
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* stz MOUSETEXT
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rts
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esc_Y ; direct cursor address
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