fix pressing of same key masking problem. Issue #4.

c64/kernal/scan_keyboard.s

@@ -179,9 +179,13 @@ ReturnNoKeys:
 	sta BufferQuantity
 	lda #$FF
 	sta last_key_matrix_position
-	sta Buffer+0
+	ldx #MaxKeyRollover-1
-	sta Buffer+1
+*
-	sta Buffer+2
+	sta Buffer,x
+	sta BufferOld,x
+	dex
+	bpl -
+
 	rts
 
 
@@ -189,6 +193,7 @@ ReturnNoKeys:
 	;; // Exit Routine for: No Activity
 
 NoActivityDetected:
+
 	;; So cancel all bucky keys
 	lda key_bucky_state
 	sta key_last_bucky_state
@@ -217,7 +222,8 @@ Main:
 
 	sty $dc00       ;// Connect all Keyboard Rows
 	cpx $dc01
-	beq NoActivityDetected
+	bne skip0
+	jmp NoActivityDetected
 
 skip0:
 
@@ -442,6 +448,7 @@ KeyHeld:
 	
 	cmp last_key_matrix_position
 	beq SameKeyHeld
+
 	;; Different key held
 	sta last_key_matrix_position
 	pha