While the rest of the world has by and large forgotten the Atari Jaguar, the generously marketed console still has a fan base, and even some dedicated hackers prodding away at it. [Cyrano Jones] is one of them, and he managed something many considered unthinkable: restoring in-game music to the Jaguar port of Doom.
The Jaguar version of the classic shooter was developed by id Software themselves, and is generally considered one of the better console ports. For example, the large number of buttons on the Jaguar controller allowed players to select weapons directly rather than having to cycle through them. Unfortunately, the complete lack of music during gameplay was a glaring omission that took several points off of an otherwise fairly solid presentation.
The common culprit blamed for this was that the Jaguar’s DSP was already being used for math processing, so it didn’t have any cycles left for music playback. Coupled with a tight deadline, id probably cut their losses and released it without in-game music rather than try and spend more time engineering a solution. To compensate for the lack of in-game music, id did include the famous soundtrack in the intermission screens rather than entirely strip it out.
As [Cyrano] found out by studying the source code that’s been available since 2003, sound effects in the Jaguar version of Doom are played using something called a “ring buffer”: a cyclical fixed-length data buffer which constantly gets outputted as audio. With a patch of unused memory he could fit a second ring buffer in, rendering the music to it with close to no performance hit elsewhere in the code and then mixing both buffers for the final audio output. It looks as though id already had some of this solution in place, but with enough issues that forced them to abandon the idea in order to release the game on time.
Software hacks are not the only things that the Jaguar fan base can do though, and a fine example of a hardware one is this custom mod showing what it could’ve looked like with the CD add-on in an integrated unit.
Thank you [Mike Watson] for the tip!