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	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 ?)
$D00034	$D00035	2	$00	"Internal" credit counters for player 1 and player 2 (BCD), used by BIOS only.
$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) $D00044 Game start compulstion (seconds in BCD) (initialized to $30) $D00046 Demo sound (1=Without) (initialized to 0)
$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	15		Game Name 0
$D002B0	$D002BF	15		Game Name 1
$D002C0	$D002CF	15		Game Name 2
$D002D0	$D002DF	15		Game Name 3
$D002E0	$D002EF	15		Game Name 4
$D002F0	$D002FF	15		Game Name 5
$D00300	$D0030F	15		Game Name 6
$D00310	$D0031F	15		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