Backup RAM

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Revision as of 23:28, 16 September 2011 by Furrtek (talk | contribs)
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The backup RAM is a battery-powered 64KiB RAM space used by MVS systems to store game scores, cab infos and income logs. Access is handled by the BIOSes.

Memory region: $D00000~$D0FFFF (Mirrored up to $DFFFFF ?).

Data structure

  • $D00000~$D0000F: Nothing ($00)
  • $D00010: "BACKUP RAM OK !",$80
  • $D00020.l: ?
  • $D00021.b: btst 0,1,2,3,4
  • $D00024.l: adresse ?
  • $D00034.l: adresse ?
  • $D00038.w: ? bit 4 tst
  • $D0003A: Start of ? (13 bytes)
  • $D00042.b: tst ?
  • $D00043.b: tst ?
  • $D00044.w: ?
  • $D00046.b: SOUND_STOP, No sound at all if non-zero
  • $D00047.b: Number of detected slots
  • $D00048.l: ?
  • $D0004C.b: ? ($3B)
  • $D00058.b: First valid slot
  • $D0005E.b: Something to do with tested slot? tst
  • $D0005A.b: heure ?
  • $D00060.w: tst ?
  • $D00104: year,month,day ? (3 bytes) Modify date
  • $D00108.b: Last tested slot
  • $D00109.b: Compared with 8
  • $D0011A: Start of ?
  • $D00122.b: ? ($23)
  • $D00124: adresses ? (4 bytes * nb of slots ?)
  • $D00144: Date (Year, Month, Day, ? *8 ?) Creation date
  • $D001AC.l: $F0F0F0F0
  • $D001B0.w: $FFFF
  • $D002A0: Title of game (16 bytes *8 ?)
  • $D00320: ?