Teletext needs no introduction. We've previously covered the CEEFAX service (the first of its kind in the world) and explored its status in Spain, but today we have the Doomguy himself blowing up demons in low resolution. Doom-teletext is an open-source project that adapts Doom's graphics to the teletext renderer, so you can play the entire game directly on a CRT television.
Notepad? Done. BIOS? Done. Commodore 64? Done. Landline phones? Done. Every time we think we've hit the ceiling of this madness, the Doomguy punches a hole through it with his shotgun. What's left to do with Doom? How else can it surprise us? GitHub user lukneu has the answer: Teletext. While it's not possible to run Doom 'on' teletext, the service is fast enough to display frames.
Doom-teletext: Playing Doom on a Teletext Service
The GitHub page explains in detail the main graphical constraints the project has to work with. Doom-teletext is based on teletext level 1 (by the author's choice), the original specification dating back to 1976. Each line has 40 characters, but not all can be used in graphics mode. Two subcategories add to this: continuous graphics and separated graphics.
Characters in graphics mode can reproduce sixels, cells divided into 2 x 3 regions. Activating each graphics mode requires a character, so the continuous mode is 39 x 2, and the separated mode is 38 x 2. With a series of additional calculations, and taking into account Doom's original 320 x 200 resolution, the final result is an image of 78 x 50 or 76 x 50 pixels, with the last four lines dedicated to the status bar (health, ammo, etc.).
The best part? Doom-teletext isn't limited to the game action. It also generates graphics for the setup menu, the help section, and even the shareware version's ads. For now, it only works on Linux, and lukneu recommends using an old CRT TV for better teletext support (apparently it doesn't work very well on newer equipment), but I think it's worth facing those difficulties.
Official site: Click here
