Abdessamad Derraz
cae30d1e8f
Nixie's layouts at vpinball e4a79a5, PinMAME memmaps at tomlogic/pinball-memory-maps 68c1b337 and game definitions at vpinball/pinmame-game-defs 6eece7e5: the subset every platform build copies into third-party/. 1,280 files, each matched to its upstream git blob, documented as three directory entries.
Williams System 6
HSTD display
At the end of the game, the machine alternates one of the player score displays with the current High Score To Date (HSTD). It backs that player score up at 0x70.
I originally assumed it always shows the HSTD in the Player 1 position, but during Visual Pinball testing with Algar, I witnessed it using the Player 3 and Player 4 positions.
If attempting to read scores from memory during "game over", it will be important to watch for the HSTD taking the place of an actual player's score in any position. We could encode this in the map somehow, using the lamp matrix. When bitmask 0x80 at address 0x17 is set, the game is showing the HSTD.
Later eras of games display the HSTD in all player positions, which makes it easier to detect.
Note: Firepower (and possibly other games) doesn't back up the tens digit to 0x72, so the game always shows 00 for that player's score during attract mode.
Game Status
Games set bits of the byte at 0x78 to indicate things like game over, tilt, extra ball, and playfield qualified. We originally used bit 0 to identify a "game over" state, but Wes Smith reported (see GitHub issue #171) that the game writes 0xFF to 0x78 between balls which will trigger an early game over.
One possible solution is to look at the bottom two bits (bit 1 is tilt)
and only accept a true "game over" when they's set to 01. Another
solution is to compare current_ball to 0 since we're reading display
memory, and it's set to zero from the match sequence. But that display
remains set to 3 when match is disabled.