commentary.

I still don't support 132 mode but switching clears the screen, homes the cursor,
and clears any scrolling regions, so it's necessary for passing the vttest suite.

vt.equ.S

@@ -36,6 +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
@@ -46,7 +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
 
@@ -93,6 +93,8 @@ read_q_tail	ds 2
 write_q_head	ds 2
 write_q_tail	ds 2
 
+master_id	ds 2
+
 	do *>256
 	err "too big"
 	fin

vt100.cda.S

@@ -37,8 +37,20 @@ ptr	ds 2
 init_cda ent
 	php
 	rep #$30
+
+*
+* rom 1 IIgs InstallCDA clobbers $3c-$43 on the direct page
+*
+
+	phd
+	pea #0
+	pld
+
 	psl #handle
 	_InstallCDA
+
+	pld
+
 	plp
 	rts
 
@@ -272,6 +284,7 @@ variables
 	jsr decawm
 	jsr decarm
 	jsr decscnm
+	jsr deccolm
 	jsr lnm
 	jsr sgr
 	jsr dectm
@@ -372,11 +385,22 @@ decscnm
 :str	asc "DECSCNM: ",00
 
 
-lnm
+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
 
@@ -385,7 +409,7 @@ lnm
 
 sgr
 	mx %10
-	ldy #line_13+4
+	ldy #line_14+4
 	ldx #:str
 	jsr print_xy_str
 	lda DPAGE+SGR
@@ -396,7 +420,7 @@ sgr
 
 dectm
 	mx %10
-	ldy #line_14+4
+	ldy #line_15+4
 	ldx #:str
 	jsr print_xy_str
 	lda DPAGE+DECTM
@@ -407,7 +431,7 @@ dectm
 
 decbm
 	mx %10
-	ldy #line_15+4
+	ldy #line_16+4
 	ldx #:str
 	jsr print_xy_str
 	lda DPAGE+DECBM
@@ -419,7 +443,7 @@ decbm
 
 decx
 	mx %10
-	ldy #line_16+4
+	ldy #line_17+4
 	ldx #:str
 	jsr print_xy_str
 	lda DPAGE+x
@@ -431,7 +455,7 @@ decx
 
 decy
 	mx %10
-	ldy #line_17+4
+	ldy #line_18+4
 	ldx #:str
 	jsr print_xy_str
 	lda DPAGE+y

vt100.csi.S

@@ -354,7 +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
@@ -396,10 +396,33 @@ mode_DECANM
 :rts	rts
 
 
-*mode_DECCOLM
-*	sty DECCOLM
-*	rts
+mode_DECCOLM
+* 80/132 mode.
+* 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

vt100.key.S

@@ -60,6 +60,9 @@ keypress ent
 	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

vt100.main.S

@@ -4,6 +4,8 @@
 	xc
 	xc
 
+	tbx on ; qasm
+
 	mx %11
 	use vt.equ
 	use apple2gs.equ
@@ -62,6 +64,9 @@ init
 	sta SETALTCHAR
 	rep #$30
 
+	jsr init_mem
+
+
 	ldx #254
 :zloop	stz 0,x
 	dex
@@ -120,6 +125,60 @@ init
 	jsr init_cda
 	rts
 
+init_mem
+*
+* see prodos technote #27
+*
+* _InstallCDA uses the memory manager ; otherwise I wouldn't bother
+* This is here to prevent MM from stomping on our memory.
+*
+
+	mx %00
+
+	stz master_id
+	_TLStartUp
+	pha
+	_MMStartUp
+	pla
+	bcs :p8
+	rts
+:p8
+	_MTStartUp
+	pea #0
+	pea #$1000
+	_GetNewID
+	pla
+	sta master_id
+
+* bank 0
+	pha
+	pha
+	pea #$0000
+	pea #$b800
+	pei master_id
+	pea #$c013
+	pea #0000
+	pea #0800
+	_NewHandle
+	pla
+	pla
+
+* bank 1
+	pha
+	pha
+	pea #$0000
+	pea #$b800
+	pei master_id
+	pea #$c013
+	pea #$0001
+	pea #$0800
+	_NewHandle
+	pla
+	pla
+
+	rts
+
+
 reset	ent
 	mx %11
 	php