refactor and MPT player examble

examples/a8/mptplayer.mfk

@@ -0,0 +1,25 @@
+const word ADDRMUS = $a000
+const word ADDRPLA = $b000
+
+byte stop @ ADDRPLA + $62d
+
+asm void comm(byte register(a) a, byte register(x) x, byte register(y) y) @ ADDRPLA extern
+asm void takt() @ ADDRPLA+3 extern
+
+void main(){
+  comm(0,ADDRMUS.hi,0)
+  comm(4,0,0)
+  while os_CH == $ff {
+    if antic_vcount == $10 {
+      antic_wsync = $e
+      gtia_colbk = $e
+      takt()
+      gtia_colbk = 0
+    }
+  }
+  stop = 0
+}
+
+const array player @ ADDRPLA = file("data/mpt_player.obj", 6)
+// Music by Adam Bienias (SoTe): Bitter Reality - Partyland 1
+const array music @ ADDRMUS = file("data/bitter_reality_4.mpt", 6)

examples/a8/systemoff_example.mfk

@@ -17,6 +17,21 @@
 // PORTB_SYSTEM_ON    = %00000001; portb bit value to turn System on
 //
 // ================================================
+//
+// Now the routine that lets you get to
+// the RAM that is under the OS.
+// There are actually 2 memory areas
+// present:
+//    4K at $C000 to $CFFF, 49152 to 53247
+//   10K at $D800 to $FFFF, 55296 to 65535
+//
+// The last 6 bytes of the 10K area are not
+// usable, since that is where the interrupt
+// routines are located.  Therefore do not
+// use any RAM above $FFF9 (65529) or you
+// will crash the system.
+//
+// ================================================
 
 byte nmien = $c0
 

include/a8_antic.mfk

@@ -6,7 +6,7 @@
 
 // ANTIC Display List Instruction Set
 // THE DISPLAY LIST CANNOT CROSS A 1K BYTE MEMORY BOUNDARY UNLESS A JUMP INSTRUCTION IS USED!
-const byte LMS     = $40          // Load memory scan 10-bit counter, $fff boundary.
+const byte LMS     = $40          // Load memory scan 12-bit counter, $0-$fff boundary.
 const byte DLI     = $80          // Display list interrupt - Interrupt CPU at beginning of last scan line.
 const byte HSCROL  = $10          // Enable horizontal scrolling.
 const byte VSCROL  = $20          // Enable vertical scrolling.