No, the idea isn't exactly new: if you search for something like “Doom C64” on Google, you'll quickly find several initiatives that bring together these two inexhaustible classics, but what we have here today is different. Thanks to an expansion cartridge known as RAD and the project RAD-Doom, enthusiasts of the Commodore 64 and 128 can now play the Doom demo using much of the original hardware, including the 1351 mouse.
Lego bricks, the Notepad, a BIOS, landline phones… for Doom, anything is compatible if we're brave enough. Late or early, a hack, mod, port, adaptation or conversion will appear that extends the infernal hunt of the Doomguy. Classic computers are no exception, and the first on our list is the Commodore 64. Enthusiasts have done true miracles with the game's code, but the C64 can't run Doom on its own, unless… it gets a little help.
RAD-Doom: "Rip and tear" on a Commodore 64
This video published on the emulaThor channel shows us RAD-Doom, a technical demo developed by the user Frenetic, which enables users of a Commodore 64 or 128 to run the shareware version of Doom on their machines using the RAD expansion cartridge. This cartridge can emulate memory modules (up to 16 MB, or 4 MB in GeoRAM/NeoRAM mode), but it also works as an 'external CPU' for the Commodore, courtesy of a Raspberry Pi 3A+, 3B+ or Zero 2 W.
RAD-Doom takes advantage of that role of the RAD cartridge, however, emulaThor explains that the graphics are rendered by the VIC-II chip on the Commodore 64, and the sound is handled by the classic SID (although there are other options, among which SIDKick stands out). As if that weren't enough, the demonstration starts with the keyboard, but later adds the 1351 mouse.
The second video from emulaThor focuses on the technical differences of the sound. Everything we hear comes from a standard SID 8580, then continues with the aforementioned SIDKick (a drop-in replacement), and finally combines the SIDKick with the MT32-Pi to process MIDI. In the last part of the video he uses a DigiMax adapter.
In summary, playing Doom on the Commodore 64 requires a good dose of DIY, but retro hardware fans won't think twice, and the audio options are too extensive to ignore. Moreover, all the necessary material is open source, from the RAD cartridge to RAD-Doom itself.
RAD cartridge: Click here
RAD-Doom: Click here
