Start on FILE i/O

rom/init.s

@@ -77,9 +77,9 @@ L4098:
       sta     INPUTBUFFER-4
       ldx     #TEMPST
       stx     TEMPPT
-      lda     #<$BC00     ; Start of IO
+      lda     #<IO_SCREEN     ; Start of IO
       sta     MEMSIZ
-      lda     #>$BC00
+      lda     #>IO_SCREEN
       sta     MEMSIZ+1
       sta     FRETOP
       sty     FRETOP+1