"PC speaker sound effects"@en . . "PC speaker format specification"@en . "While digital sound effects have the prefix \"DS\" inside the Doom IWAD, PC speaker sound effects have the prefix \"DP\". For example, the sound of a pistol firing is stored in the lump named \"DSPISTOL\"; the corresponding PC speaker sound effect is named \"DPPISTOL\". The format is notable in that it was the last WAD lump format to be properly decoded and understood. The Doom source code release did not include the PC speaker code, as it was part of the proprietary DMX sound code that was removed from the source code before its release (evidence of this can be seen in the Heretic source code). As PC speaker sound effects were no longer necessary by this time, little effort was made in properly determining the format. The format was finally properly reverse-engineered in 2007 by Andrew Apted and Simon \"Fraggle\" Howard."@en . "While digital sound effects have the prefix \"DS\" inside the Doom IWAD, PC speaker sound effects have the prefix \"DP\". For example, the sound of a pistol firing is stored in the lump named \"DSPISTOL\"; the corresponding PC speaker sound effect is named \"DPPISTOL\". The format was finally properly reverse-engineered in 2007 by Andrew Apted and Simon \"Fraggle\" Howard."@en . "14832"^^ . .