Unused Game Content ~ MegaMan Xtreme Unused Super Game Boy SGB Programming
6http://gamehacking.org/vb/threads/12747-nensondubois-codes
Just a quick example of how the palette can become awkward at times since Capcom didn't bother finishing SGB support. the only notable thing aside from the blue palette is the ATTR_EN command being active disabling border screensavers. Really weird that this was unfinished, but it goes to show what was planned to some degree.
By enabling the Super Game Boy flag located at 0x0146 and modifying it to 03, or using the Game Genie code 031-46F-E6A you can enable the long lost Super Game Boy single blue palette. Super Game Boy programming appears to have been in active development and was discontinued right round the planning stages for the border. Interestingly, ATRC_EN is set to 01 for unknown reasons. This disables the Super Game Boy border screensavers.
Notice how the licensed by Nintendo logo is glitched-out when Super Game Boy features are enabled and that Mega Man X looks inverted.
Located at 0x611A is the main listing of the unused commands. ATTR_EN is located at 0x5F9D.
795D08000B8CD0F46000000000000000 - DATA_SND
795208000BA9E79F01C07EE8E8E8E8E0 - DATA_SND
794708000BC4D016A5CBC905D010A228 - DATA_SND
793C08000BF012A5C9C9C8D01CA5CAC9 - DATA_SND
793108000B0CA5CAC97ED006A5CBC97E - DATA_SND
792608000B39CD480CD034A5C9C980D0 - DATA_SND
791B08000BEAEAEAEAEAA901CD4F0CD0 - DATA_SND
791008000B4C2008EAEAEAEAEA60EAEA - DATA_SND
B9010000000000000000000000000000 - MASK_EN
B9000000000000000000000000000000 - MASK_EN
59000000000000000000000000000000 - PAL_TRN
A1000000000000000000000000000000 - PCT_TRN
A9000000000000000000000000000000 - ATTR_TRN
99000000000000000000000000000000 - CHR_TRN
99010000000000000000000000000000 - CHR_TRN
510000000000000000C0000000000000 - PAL_SET
61010000000000000000000000000000 - ATTR_EN
http://board.gscentral.org/retro-hacking/52815-6.htm
http://tcrf.net/Mega_Man_Xtreme