I studied the 68k code for the OutRun Philko bootleg. This is identifiable by the copyright message reading BETA as opposed to SEGA, as shown in the screenshot below.
Although the hardware is different to the original Sega boardset (see MAME source code for details), it turns out that the game code is identical to the standard Rev B edition. The only changes are in fact the copyright message, the patched rom checksum and the encoding detailed below.
Bizarrely, Philko felt compelled to perform some crude encryption on their code by bitswapping it. As documented in the MAME source code, for the main CPU bits 11,12 and 6,7 should be swapped. For the sub CPU bits 14,15 and 2,3 should be swapped.
Here's a picture of the boardset, kindly provided by Luke Wells.
Here are some closeups I found on ebay:
Here are photos of a bootlegged cabinet, provided by Francois:
Lots of differences! (Start button, Steering wheel, bezel etc.)
Bootleg cabinet interior shot. Click to enlarge
So this means a couple of things to bootleg board owners: I can potentially provide a version of OutRun Enhanced Edition if there's demand. Or owners can patch with a bitswapped Sega revision B romset, if they dislike the BETA copyright message.
Some questions of my own:
- Why identify the boardset as a bootleg by changing the copyright message?