Software DIPs



Software DIPs are a list of a maximum of 14 game-specific settings. They can be modified from the MVS System ROM menu, or with system ROM hacks for other systems.

The settings names and their possible values are stored in the game's 68k program header in a specific format, read by the system ROM to form a menu.

On the MVS, the settings are saved for each game in the backup RAM.

The settings are copied from backup RAM to user RAM to BIOS_GAME_DIP ($10FD84) just before the game is started up. If no settings are found, they're initialized to the default values.

(Does the system ROM check values pulled from the backup RAM against the bounds given by the game ? Can a corrupt backup RAM save make games crash with out of bounds settings ?)

Config data description
Most of the following information by ElBarto:

Special settings list
The special settings list holds 4 entries: the first 2 are for time settings, and the last 2 are for count settings.

A time setting occupies one word, which defines the default value:
 * The upper byte is the minutes (up to 29 ?, in BCD).
 * The lower byte is the seconds (in BCD).

An unused time setting must be set to 0xFFFF.

A count setting occupies one byte, which defines the default value. It can go from 0 to 100 (not in BCD), with 0 displayed as "WITHOUT" and 100 as "INFINITE". In some versions of the system ROM, "times" is displayed after the value ?

An unused count setting must be set to 0xFF.

All special settings use a single string from the strings table, for the setting's name.

Simple settings list
Each options occupies one byte.

The upper 4 bits define the default value (starts from 0) and the lower 4 bits the number of choices.

A few games have a simple setting entry with a number of choices set to zero, just to show a "▼NEXT PAGE" string on the bottom of the MVS menu.

Examples
dc.b   "TEST ROM        "                 ; Game name dc.w   $FFFF                              ; Special settings list (none used) dc.w   $FFFF dc.b   $FF,$FF dc.b   $24                                ; Simple setting 1: 4 choices, default is #2 dc.b   $02                                ; Simple setting 2: 2 choices, default is #0 dc.b   $00,$00,$00,$00,$00,$00,$00,$00 ; String table: dc.b   "LIVES       "                     ; Simple setting 1's description dc.b   "1           "                     ; Simple setting 1's choices dc.b   "2           " dc.b   "3           " dc.b   "4           " dc.b   "HOW TO PLAY "                     ; Simple setting 2's description dc.b   "WITH        "                     ; Simple setting 2's choices dc.b   "WITHOUT     "

dc.b   "TEST ROM        "                 ; Game name dc.w   $4220                              ; Special setting 1: 42 minutes 20 seconds dc.w   $2042                              ; Special setting 2: 20 minutes 42 seconds dc.b   $42                                ; Special setting 3: 66 dc.b   $64                                ; Special setting 4: 100 ("INFINITE") dc.b   $24                                ; Simple setting 1: 4 choices, default is #2 dc.b   $02                                ; Simple setting 2: 2 choices, default is #0 dc.b   $00,$00,$00,$00,$00,$00,$00,$00 dc.b   "TIMER 1     "                     ; Special setting 1's description dc.b   "TIMER 2     "                     ; Special setting 2's description dc.b   "COUNTER     "                     ; Special setting 3's description dc.b   "COUNTER SPE "                     ; Special setting 4's description dc.b   "LIVES       "                     ; Simple setting 1's description dc.b   "1           "                     ; Simple setting 1's choices dc.b   "2           " dc.b   "3           " dc.b   "4           " dc.b   "HOW TO PLAY "                     ; Simple setting 2's description dc.b   "WITH        "                     ; Simple setting 2's choices dc.b   "WITHOUT     "