improved RETURN keyy handling, some documentation update

c64/kernal/screen/chrout_screen_del.s

@@ -58,15 +58,15 @@ chrout_screen_del_column_normal:
 	ldy PNTR
 	dey
 !:
-	iny
-	lda (PNT),y
-	dey
-	sta (PNT),y
 	iny
 	lda (USER),y
 	dey
 	sta (USER),y
 	iny
+	lda (PNT),y
+	dey
+	sta (PNT),y
+	iny
 
 	dex
 	bpl !-

c64/kernal/screen/chrout_screen_return.s

@@ -7,8 +7,23 @@
 chrout_screen_RETURN:
 
 	// RETURN clears quote and insert modes, it also clears reverse flag
+	
 	lda #$00
 	sta QTSW
 	sta INSRT
 	sta RVS
+
+	// RETURN key moves cursor two lines down in case
+	// of first line of the extended logical line
+	
+	ldy TBLX
+	cpy #24
+	beq !+                             // last line on screen - no need for a double line skip
+
+	lda LDTBL+1, y
+	bmi !+                             // current line is not continued
+
+	inc TBLX
+	jsr screen_calculate_PNT_USER
+!:
 	jmp screen_advance_to_next_line

c64/kernal/screen/screen_grow_logical_line.s

@@ -1,4 +1,5 @@
 
+// YYY growing logical line in the last line is unstable
 
 
 screen_grow_logical_line_screen_up:

c64/kernal/screen/screen_preserve_sal_eal.s

@@ -5,11 +5,19 @@ screen_preserve_sal_eal:
 	plx_trash_a
 	ply_trash_a
 
+	// Note: While the following routine is obvious to any skilled
+	// in the art as the most obvious simple and efficient solution,
+	// it results in a relatively long verbatim stretch of bytes when
+	// compared to the C64 KERNAL.  Thus we have swapped the order,
+	// just to reduce the potential for any argument of copyright
+	// infringement, even though we really do not believe that the
+	// routine can be copyrighted due to the lack of creativity.
+
 	lda SAL+0
 	pha
-	lda SAL+1
-	pha	
 	lda EAL+0
+	pha	
+	lda SAL+1
 	pha
 	lda EAL+1
 	pha

c64/kernal/screen/screen_restore_sal_eal.s

@@ -5,13 +5,21 @@ screen_restore_sal_eal:
 	plx_trash_a
 	ply_trash_a
 
+	// Note: While the following routine is obvious to any skilled
+	// in the art as the most obvious simple and efficient solution,
+	// it results in a relatively long verbatim stretch of bytes when
+	// compared to the C64 KERNAL.  Thus we have swapped the order,
+	// just to reduce the potential for any argument of copyright
+	// infringement, even though we really do not believe that the
+	// routine can be copyrighted due to the lack of creativity.
+
  	pla
  	sta EAL+1
  	pla
- 	sta EAL+0
- 	pla
  	sta SAL+1
  	pla
+ 	sta EAL+0
+ 	pla
  	sta SAL+0
 
  	jmp screen_common_sal_eal