Backup RAM

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The backup RAM is a battery-powered 64KiB RAM space used by the MVS to store game scores, cab infos and income logs. Access can be handled by BIOS calls.

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

Data structure

All offset are taken from the sp-s2.bin system ROM.

Start End Size Data Description
$D00000 $D0000F 16 $00 Unused, fill with $00
$D00010 $D0001F 16 "BACKUP RAM OK!Ç" The routine at $C125C8 will check if this string is present, if not it will test the ram (using the test_ram routine at $C13134) and re-init the backupram
$D00020 $D00021 2 Coin deposit related (rising edge finding), old and new value of REG_STATUS_A
$D00022 $D00023 2 Temp value for the coin deposit rising edge finding
$D00024 $D00025 2 Internal coin counter (not credit)
$D00026 $D0002F ?
$D00034 $D00035 2 $00 "Internal" credit counters for player 1 and player 2 (BCD)
$D00036 $D00039 ?
$D0003A $D00045 12 Cab settings.
$D0003A
Coins needed for crediting player 1 (initialized to $01)
$D0003B
Credits added to player 1 (initialized to $01)
$D0003C
Coins needed for crediting player 2 (initialized to $01)
$D0003D
Credits added to player 2 (initialized to $02)
$D00042
Game select (1=Free, 0=Only when credited) (initialized to 0)
$D00043
Game start compulsion (0 = enabled, 1 = disabled)
$D00044
Game start compulsion time (max time in seconds in BCD between inserting a coin and starting the game) (initialized to $30)
$D00046
Demo sound (1=Without) (initialized to 0)
$D00046 $D00046 1 SOUND_STOP No sound at all if non-zero (except coinage sound effect)
$D00047 $D00047 1 SLOT NUMBER Number of detected slots (2 for slot1)
$D00048 $D0004B 4 PLAY TIME Counter of second played on the game in hex.

Reset to 0 by SYSTEM_RETURN.

$D0004C $D0004C 1 PLAY_TIME_FRAME_TIMER Frame timer, start at $3C, decremented each frame. When the counter reach $00, PLAY_TIME is incremented and the counter is reseted to $3C
$D0004D $D00057 ?
$D00058 $D00058 1 First slot number with a boot logo flag to 0 (playable by the system ROM)
$D0005A $D0005D 4 HHMMSSFF Timer based on frames.
  • FF: frame down-counter ($3C to $00)
  • SS: second counter ($00 to $3B)
  • MM: minute counter ($00 to $3B)
  • HH: hour counter *4 ($00 to $60 by 4 steps)
$D0005E $D00103 ?
$D00104 $D00107 4 YYMMDDdd Current date
$D00108 $D00108 1 Selected slot number (start at 0) Output directly to the EL panels
$D00109 $D00109 1 EL_PANEL State of the EL-PANEL ???
$D0010A $D0010D 4 Detailed game start book address
$D0010E $D00111 4 Total game start book address
$D00112 $D00115 4 Detailed cabinet coin book address (sub 0x240 for the start book one)
$D00116 $D00119 4 Current month cabinet coin book address (sub 0xC for the start book one)
$D0011A $D00121 ?
$D00122 $D00123 2 $23 The init_backupram routine write $23 there, purpose unknown.
$D00124 $D00127 4 Slot-1 NGH number and bram game block ID (see below) If not present $0000 as NGH and $FFFF as game name ID
$D00128 $D0012B 4 Slot-2 NGH number and bram game block ID (see below) If not present $0000 as NGH and $FFFF as game name ID.

On a slot1 always unset (slot1 are slot2 with the second one empty)

$D0012C $D0012F 4 Slot-3 NGH number and bram game block ID (see below) If not present $0000 as NGH and $FFFF as game name ID
$D00130 $D00133 4 Slot-4 NGH number and bram game block ID (see below) If not present $0000 as NGH and $FFFF as game name ID
$D00134 $D00137 4 Slot-5 NGH number and bram game block ID (see below) If not present $0000 as NGH and $FFFF as game name ID
$D00138 $D0013B 4 Slot-6 NGH number and bram game block ID (see below) If not present $0000 as NGH and $FFFF as game name ID
$D0013C $D0013F 4 Slot-7 NGH number and bram game block ID (see below) If not present $0000 as NGH and $FFFF as game name ID
$D00140 $D00143 4 Slot-8 NGH number and bram game block ID (see below) If not present $0000 as NGH and $FFFF as game name ID
$D00144 $D00147 4 YYMMDDdd Slot-1 book creation time YEAR-MONTH-DAY-day number
$D00148 $D0014B 4 YYMMDDdd Slot-2 book creation time YEAR-MONTH-DAY-day number
$D0014C $D0014F $4 YYMMDDdd Slot-3 book creation time YEAR-MONTH-DAY-day number
$D00150 $D00153 4 YYMMDDdd Slot-4 book creation time YEAR-MONTH-DAY-day number
$D00154 $D00157 4 YYMMDDdd Slot-5 book creation time YEAR-MONTH-DAY-day number
$D00158 $D0015B 4 YYMMDDdd Slot-6 book creation time YEAR-MONTH-DAY-day number
$D0015C $D0015F 4 YYMMDDdd Slot-7 book creation time YEAR-MONTH-DAY-day number
$D00160 $D00163 4 YYMMDDdd Slot-8 book creation time YEAR-MONTH-DAY-day number
$D00164 $D001A3 ?
$D001A4 $D001A7 4 Current month game start book
$D001A8 $D0021F ?
$D00220 $D0029F 16*8 Games soft DIPs settings (in which order ?)
$D002A0 $D002AF 16 bram block 0 game name
$D002B0 $D002BF 16 bram block 1 game name
$D002C0 $D002CF 16 bram block 2 game name
$D002D0 $D002DF 16 bram block 3 game name
$D002E0 $D002EF 16 bram block 4 game name
$D002F0 $D002FF 16 bram block 5 game name
$D00300 $D0030F 16 bram block 6 game name
$D00310 $D0031F 16 bram block 7 game name
$D00320 $D0131F $1000 bram block 1 data
$D01320 $D0231F $1000 bram block 2 data
$D02320 $D0331F $1000 bram block 3 data
$D03320 $D0431F $1000 bram block 4 data
$D04320 $D0531F $1000 bram block 5 data
$D05320 $D0631F $1000 bram block 6 data
$D06320 $D0731F $1000 bram block 7 data
$D07320 $D0831F $1000 bram block 8 data
$D09BA0 $D09DE0 $240 YYMMDDdd - COIN1 - COIN2 - SERVICE Bookkeeping - Current month coin

Each entry is $10 byte long

$D09DE0 $D0A01F $240 YYMMDDdd - PLAY - CONTINUE - TIME Bookkeeping - Current month play

Each entry is $10 byte long

$D0A020 $D0A0DF $C0 00000000 - COIN1 - COIN2 - SERVICE Bookkeeping - Year coin
$D0A0E0 $D0A19F $C0 00000000 - PLAY - CONTINUE - TIME Bookkeeping - Year play