Backup RAM
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
All offset are taken from the sp-s2.bin bios.
| Start | End | Size | Data | Description |
| $D00000 | $D0000F | $F | $00 | Unused, fill with $00 |
| $D00010 | $D0001F | $F | "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 ?) | |
| $D00034 | $D00035 | $2 | $00 | "Internal" credit counters for player 1 and player 2 (BCD), used by BIOS only. |
| $D0003A | $D00045 | $C | $01010102010101030000303B0000 | the init_backupram routine ($C125F4) will copy $C data from $C1F000 there. |
| $D00046 | $D00046 | $1 | SOUND_STOP | No sound at all if non-zero |
| $D00047 | $D00047 | $1 | SLOT NUMBER | Number of detected slots (2 for slot1) |
| $D00048 | $D00059 | ? | ||
| $D0005A | $D0005D | $4 | HHMMSSMM | Current time, hour is mult by 4 (???), MM is the milliseconds. |
| $D0005E | $D00103 | ? | ||
| $D00104 | $D00107 | $4 | YYMMDDdd | Current date |
| $D00108 | $D00109 | ? | ||
| $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 game name ID (see below) | If not present $0000 as NGH and $FFFF as game name ID |
| $D00128 | $D0012B | $4 | Slot-2 NGH number and game name 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 game name ID (see below) | If not present $0000 as NGH and $FFFF as game name ID |
| $D00130 | $D00133 | $4 | Slot-4 NGH number and game name ID (see below) | If not present $0000 as NGH and $FFFF as game name ID |
| $D00134 | $D00137 | $4 | Slot-5 NGH number and game name ID (see below) | If not present $0000 as NGH and $FFFF as game name ID |
| $D00138 | $D0013B | $4 | Slot-6 NGH number and game name ID (see below) | If not present $0000 as NGH and $FFFF as game name ID |
| $D0013C | $D0013F | $4 | Slot-7 NGH number and game name ID (see below) | If not present $0000 as NGH and $FFFF as game name ID |
| $D00140 | $D00143 | $4 | Slot-8 NGH number and game name 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 |
| $D001A4 | $D002A7 | $4 | Current month game start book | |
| $D001A8 | $D002AB | $4 | ? | |
| $D002A0 | $D002AF | $F | Game Name 0 | |
| $D002B0 | $D002BF | $F | Game Name 1 | |
| $D002C0 | $D002CF | $F | Game Name 2 | |
| $D002D0 | $D002DF | $F | Game Name 3 | |
| $D002E0 | $D002EF | $F | Game Name 4 | |
| $D002F0 | $D002FF | $F | Game Name 5 | |
| $D00300 | $D0030F | $F | Game Name 6 | |
| $D00310 | $D0031F | $F | Game Name 7 | |
| $D00320 | $D0131F | $1000 | Game 1 data | |
| $D01320 | $D0231F | $1000 | Game 2 data | |
| $D02320 | $D0331F | $1000 | Game 3 data | |
| $D03320 | $D0431F | $1000 | Game 4 data | |
| $D04320 | $D0531F | $1000 | Game 5 data | |
| $D05320 | $D0631F | $1000 | Game 6 data | |
| $D06320 | $D0731F | $1000 | Game 7 data | |
| $D07320 | $D0831F | $1000 | Game 8 data |