What you found in Lemmings 2 on the Genesis:
- at $150 is actually part of the ROM header; the number you saw is the serial number, followed by the checksum. Here's how the Sega part of the header is laid out:
$100-$10F - "SEGA MEGA DRIVE ", "SEGA GENESIS ", etc. $110-$11F - "(C)//// YYYY.MMM"; //// is SEGA or T-xx for third parties and the date is either the build date or the release date $120-$14F - Japanese title $150-$17F - international title $180-$18D - serial number $18E-$18F - checksum $190-$19F - peripheral support (one character per peripheral) $1A0 long - ROM start (not sure why these are supplied) $1A4 long - ROM end $1A8 long - RAM start $1AC long - RAM end $1B0 long - "RA" and two bytes for save RAM; all spaces otherwise $1B4 long - SRAM start or spaces if no save RAM $1B8 long - SRAM end or spaces if no save $1BC-$1EF - technically peripheral support string but only used by modem games; if any game actually uses this area it might count as something for the wiki but you'd have to check $1F0-$1FF - region support (either J, U, E, a combination, or a single byte for the newest games that is a bitfield of region values)
- Other than the first four bytes at $100, this entire block is documentation and has no effect on the game (unless the game code actually uses it).
- The DEVELOPED FOR USE strings are used — change the emulator region to ne not supported by the given ROM and restart to see them
Just to let you know - Andlabs 19:08, 9 April 2012 (EDT)
"did you even played the game?"
In addition, you can blame DJ Shockwave for labeling that "Game Over/No Continues" track on the Genesis version as "Unused". Apparently, he didn't know about the "no continues" condition, either.