case switch fixes, support missing PETSCII control codes

c64/kernal/cint_real.s

@@ -96,7 +96,9 @@ cint_brk: // entry for BRK and STOP+RESTORE - XXX, where should it start?
 	// Set maximum keyboard buffer size (Compute's Mapping the 64 p215)
 	ldx #10
 	stx XMAX
+	
 	// Put non-zero value in MODE to enable case switch
+	ldx #$00
 	stx MODE
 	
 	// Set default I/O devices (see SCINIT description at http://sta.c64.org/cbm64krnfunc.html)

c64/kernal/scnkey_tww_ctr.s

@@ -367,11 +367,11 @@ next_row:
 	beq no_case_toggle
 
 	lda MODE
-	beq no_case_toggle
+	bne no_case_toggle
 	
-	lda $D018
+	lda VIC_YMCSB
 	eor #$02
-	sta $d018
+	sta VIC_YMCSB
 
 no_case_toggle:	
 	

c64/kernal/screen/chrout_screen_control.s

@@ -110,17 +110,19 @@ chrout_try_MODE_TXT:
 	cmp #$0E
 	bne !+
 
-	// XXX
-
-	jmp chrout_screen_done
+	lda VIC_YMCSB
+	ora #$02    // to lower case
+	bne mode_l1 // branch always
 !:
 chrout_try_MODE_GFX:
 
 	cmp #$8E
 	bne !+
 
-	// XXX
-
+	lda VIC_YMCSB
+	and #$02 // to upper case
+mode_l1:
+	sta VIC_YMCSB
 	jmp chrout_screen_done
 !:
 chrout_try_COLOR:
@@ -140,7 +142,8 @@ chrout_try_SHIFT_ENABLE:
 	cmp #$09
 	bne !+
 
-	// XXX
+	lda #$00 // enable SHIFT+VENDOR combination
+	sta MODE
 
 	jmp chrout_screen_done
 !:
@@ -149,7 +152,8 @@ chrout_try_SHIFT_DISABLE:
 	cmp #$08
 	bne !+
 
-	// XXX
+	lda #$80 // disable SHIFT+VENDOR combination
+	sta MODE
 
 	jmp chrout_screen_done
 !:
@@ -167,16 +171,12 @@ chrout_try_CLR:
 	bne !+
 
 	jsr clear_screen
+clr_l1:
 	jmp chrout_screen_done
 !:
 chrout_try_INS:
 
 	cmp #$94
-	bne !+
+	bne clr_l1 // unknown code or key does not need handling
 
 	jmp chrout_screen_ins
-!:
-chrout_screen_control_done:
-
-    // unknown code or key does not needs 
-	jmp chrout_screen_done