We've previously explored ways to play Doom in a BIOS, in Notepad, with an ultrasound scanner, and even inside itself. But what we have here today is a hack that we can, from a certain point of view, call "official": Doom in multi-monitor mode. With the correct version and enough hardware, players could connect four computers over a network and use them as drones to extend the screen... in 1993!
Doom is not just one of the foundational pillars of the FPS genre. The game arrived on the market with impressive technological achievements that completely revolutionized the concept of multiplayer gaming. I had the privilege of living through that golden era of home and local multiplayer, first with a serial cable, then using the parallel port, and finally with network cards over LSL and IPX. Beyond the speed increase, setting up a LAN raised the number of players per match from two to four. Deathmatch sessions with shotguns and rocket launchers with the volume turned up to max were glorious, but you had to be very respectful of the coaxial cables: If you looked at them wrong, they'd suffer an anxiety attack and lose the connection.
However, that wasn't all we could do with Doom. Shelby from the Tech Tangents channel reminds us that version 1.1 of the game (the first recorded release) had multi-monitor support... but not in the way you imagine. It requires a minimum of three computers on a network under MS-DOS for this to work, with two of them reduced to drones. His latest video shows us the setup process...
Playing Doom in Multi-Monitor Mode on MS-DOS
... but the first thing you need to understand about retro computers is that things never go as planned. In one section of the video, Shelby verifies that the four Pentium 4 computers with Intel motherboards (excessive hardware for this task) work correctly, but also discovers that one of the floppy drives is destroying disks, so he turns to a Gotek emulator to install the necessary software.
The next challenge is the drivers, and as expected from Intel, there were no appropriate files on their site. Shelby found a compatible driver on Lenovo's support page, within a package for ThinkPad laptops.
Configuring the network cards under MS-DOS isn't complicated, though we need to know which lines to edit in the CFG file and the correct order of execution. The former depends on each card, but the latter is LSL -> driver -> IPX. The Doom installation presents no problems, except for the lack of sound (the board he tested is PCI, an eternal headache under that operating system), and the excessive speed of the game when starting a network match. Once Shelby activated multi-monitor mode, everything normalized.
The end result is an excellent setup with three monitors, left-center-right using an offset of 90 degrees, and a fourth monitor with the automap loaded. The presence of the rocket launcher and the chaingun in E1M1 draws a lot of attention, but multi-monitor mode is technically a multiplayer match, and that activates additional weapons in the level. Once again, there are no mods, no ports, no patches: This is Doom in its original version 1.1, running on native MS-DOS. In fact, there's a bug in the automap that forces that fourth computer to 'see' the map before presenting the data (making the automap irrelevant). The video is a true retro pleasure, and if you have half an hour available, you shouldn't miss it.
