The neogeo bios can be accessed in mame172 via the menu dipswitch settings
For games like viewpoint (neogeo) this means you can play with 2 players simultaneously!
here's how to do this:
in the game, press TAB for menu and Set the dip switches setting to on and select reset
on the neogeo BIOS screen press start+A+B+C+D
go to"Setting up soft dip" page 2 and from here select "Slot 1 viewpoint"
here, go to page 2 and change 2 player "alternate" to "simultaneous"
now go back (i think with C button) and exit
when ok it will diplay "DIP SW 1 OFF !!!"
TAB again and set the dip switch settings back to off
reset the game and from now on you can play 2 player simultanously
It even saves the setting so you wont have to do it again next time
