vt52 might be more or less complete now.

vt100.main.S

@@ -259,9 +259,13 @@ ctrl_0c ; form feed.
 * if LNM mode, need to update cursor as well.
 
 :simple
+	cmp #23
+	beq :rts
 	inc y
 	jmp recalc_cursor_y
 
+:rts	rts
+
 ctrl_0d ; carriage return - cursor to column 0.
 	stz x
 	jmp recalc_cursor_x

vt100.screen.S

@@ -288,7 +288,12 @@ draw_char ent
 	rts	
 
 
+* erase screen commands are not affected by origin or scrolling region.
+
 erase_screen ent
+erase_screen_2 ent
+* erase the entire screen.
+
 	mx %11
 	lda erase_char
 * fall through
@@ -618,10 +623,99 @@ erase_line_1 ent
 :exit	plp
 	rts
 
+erase_screen_0 ent
+* erase cursor to end of screen.
+	mx %11
+	jsr erase_line_0
+	php
+	rep #$30
 
-* erase screen commands are not affected by origin or scrolling region.
-* erase screen
-* erase start -> cursor
-* erase cursor -> end
+	lda y
+	inc
+	cmp #24
+	bcs :exit
+	asl
+	tay
+	lda erase_char
+
+:loop
+
+	sty r0
+	ldx text,y
+	ldy #19
+:loop0
+	sta >$000000,x
+	inx
+	inx
+	dey
+	bpl :loop0
+
+	ldy r0
+	ldx text,y
+	ldy #19
+:loop1
+	sta >$010000,x
+	inx
+	inx
+	dey
+	bpl :loop1
+
+	ldy r0
+	iny
+	iny
+	cpy #24*2
+	bcc :loop
+
+:exit
+	plp
+	rts
+
+erase_screen_1 ent
+* erase beginning of screen to cursor.
+	mx %11
+	jsr erase_line_1
+
+	php
+	rep #$30
+
+	lda y
+	dec
+	bmi :exit
+	asl
+	tay
+	lda erase_char
+
+:loop
+
+	sty r0
+	ldx text,y
+	ldy #19
+:loop0
+	sta >$000000,x
+	inx
+	inx
+	dey
+	bpl :loop0
+
+	ldy r0
+	ldx text,y
+	ldy #19
+:loop1
+	sta >$010000,x
+	inx
+	inx
+	dey
+	bpl :loop1
+
+	ldy r0
+	dey
+	dey
+	bpl :loop
+
+
+:exit
+	plp
+	rts
+	rts
 
 	sav vt100.screen.L

vt100.vt52.S

@@ -17,7 +17,7 @@
 
 	ext write_modem,draw_char
 	ext advance_x,recalc_cursor,recalc_cursor_x,recalc_cursor_y
-
+	ext scroll_up,scroll_down
 
 vt52_esc ent
 * ABCDFGHIJKYZ<>=
@@ -142,18 +142,31 @@ esc_D ; cursor left
 esc_I ; cursor up w/ line scroll
 * based on testing, scrolling only occurs within the
 * scroll region.
-	rts
-esc_J rts
-esc_K rts
+	lda y
+	cmp DECTM
+	beq :scroll
+	cmp #0
+	beq :rts
+	dec y
+	jmp recalc_cursor_y
 
+:scroll	jmp scroll_up
+:rts	rts
+
+esc_J
+* erase cursor to end of screen.
+	ext erase_screen_0
+	jmp erase_screen_0
+	rts
+esc_K
+* erase cursor to end of line
+	ext erase_line_0
+	jmp erase_line_0
 
 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