Deep Into the Code
Deep into the Code is a song from Doom series which was composed by Bobby Prince who wrote the track in Sequencer Plus Gold with apparent musical inspiration from Slayer's Behind the Crooked Cross. Prince's mental inspiration came from watching Doom's lead programmer, John Carmack, working on the Doom engine very late at night.
Bobby Prince had this to say about the track:
This is the original port of Doom where Deep into the Code appears. It is played in E3M3: Pandemonium (and in E4M3: Sever the Wicked in the expansion pack, Ultimate Doom (DOS)).
This track's internal name is "D_E3M3" and it is not included in the shareware version of the game.
Deep into the Code, in the Game Boy Advance port of Doom, plays in the same level as in the PC DOS version, Level 18: Pandemonium. This is curiously the first song to play properly on a level where it should do without any "shifting" to the next song.
This is the only song used in a home console version of Doom. The other ones rather play different tracks like On the Hunt.