Back to the Future Part III (Genesis)

Back to the Future Part III
Developer: Probe Software Publishers: Arena Entertainment (US), Image Works (EU), Tec Toy (BR) Platform: Genesis Released in US: 1991 Released in EU: 1991 Released in BR: 1991 This game has hidden developer credits. This game has hidden development-related text. This game has a hidden level select.

Play through the movie in four completely different levels! If "Mad Dog" Tannen's boys don't get you, the punishing and unrelentingly-hard gameplay will!

Level Skip

Press Start to pause the game, then hold A and press Up, Down, Left, Right. If done correctly, you'll skip to the next level automatically. Entering the code in the final level will let you see the game's ending.

(Source: GameFAQs)

Unused Palette Bits

The Genesis hardware expects colors in a palette to be stored in 16 bits of the format 0000BBB0GGG0RRR0, where R, G, and B are the 3-bit red, green, and blue components of the color (with the lowest bit of each nibble ignored and unused). However, this game mistakenly uses the format 00000BBB0GGG0RRR (with the highest bit of each nibble unused), limiting the components to the lower 4 of the 8 possible values. Since smaller values represent darker colors, the game's palettes appear much darker than they're supposed to.

(Source: Sega Retro)

Unused Text

Developer Credit

This text appears at 0x380 in an uninterleaved US ROM:

jim.b july91

Jim Baguley is the programmer for the Genesis port of this title. Though this appears to be some development leftover or signature, it actually serves a purpose: a routine at 0x31e tests a memory address for a copy of this string, and if not found, the console is assumed to be on "first boot" (uninitialized state) and the high score table is cleared to zero.

Copyright Screen

There are two versions of the copyright screen (which displays immediately after the SEGA logo), one for the US and one for the EU. Arena Entertainment was the publisher for the US version, while Image Works published the EU version. However, the text for *both* screens is present in *both* ROMs, and simply uses a different pointer elsewhere in the ROM to choose which to display.

In other words, by changing bytes at offset 0x55e from 0x186d to 0x1784 in the US ROM, you can cause it to display the EU copyright instead.

EU Version	US Version

There is also an unused production credit string at 0x1772, which reads simply:

PRODUCTION
    OF

Instrument Text

The following text can be found at 0x7C130 in an uninterleaved US ROM:

FM Voice Bank by JMP 1991  v 0.1

A list of sample or instrument names follows afterwards. "JMP" likely refers to John Phillips, who is credited as the music programmer in the title screen.

QUIET     
Bdrum     
SnareDrum1
PINK NOISE'Y
Throw     
SnareDrum1
Bell      
Aargh     
Elec Grnd2
Elec Grnd2
SnareDrum1
Throw     
Elec Grnd2
SnareDrum1
Aargh     
Aargh     
SnareDrum1
Aargh     't
Aargh     
Aargh     
SnareDrum1
Bell      
PINK NOISE
SnareDrum1
Wall      
Aargh     'n
Bdrum     
FM PULSE  1\
PINK NOISE
QUIET     
QUIET     
QUIET     
QUIET     
EBass     
Guitar    1x
Bdrum     
Banjo     
Snare     
GuitarUP2 1x
GuitarUP1 1x
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
PhaseGrand
PhaseGrand
Elec organ
Banjo     
SnareDrum1
SnareDrum1
Wall      
Harpsi low
Harpsi low
Harpsi low
Bdrum     
PINK NOISE
SnareDrum1
Aargh     
Aargh     't
Bell      
Baroque   
EBass     
Snare     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
Brass    41l
Solid Bass
QUIET     
Theater   ?h
Theater   ?t
Clockwerks
QUIET     
Theater   ?
Strings  3
Strings  3
Theater   
Theater   
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
QUIET     
empty     1
SnareDrum1
BassDrum  
Bell      
Throw     
Wall      
Aargh     
SnareDrum1