If you had one monitor back in the 8-bit era, instead of having to wait to use the family TV, you were already amongst the blessed. If you had five, maybe you worked at a computer store– but if you did, you could have done what [The 8-Bit Guy] demonstrates in a recent YouTube video and plug all five (5) monitors into a Commodore 128.
The computer isn’t modified in any way– well, except for the now standard use of an SD card disk emulator– so what gives? Well, you probably guessed he’s splitting up the colour signal into multiple monochrome images, but since the C128 actually has an RGBI, that I– intensity– actually gives another signal that can be broken out. That makes for four screens being driven from that port via composite, all sharing the same sync. The hardware for that was actually designed for [The 8-Bit Guy] by [Joe Burks] who open sourced the design on GitHub. He’s also selling them on Lectronz.
The fifth screen, of course, is driven by the VIC-II chip that Commodore provided for composite output to begin with. The interesting part is as much the software as the hardware, and while [The 8-Bit Guy] explains some of the thinking behind what he’s doing, he doesn’t link to any BASIC. If you know your way around a Commodore, you should be able to encode the multi-colour images required to do the splits.
For the people who prefer “real computers” — that is IBM compatible PCs– [The 8-Bit Guy] goes a bit outside of his 8-bit comfort zone to demonstrate that this same trick works quite well with the 16-color modes of EGA. With sixteen colours split between the two monitors, you of course get two colours each– combine the dithering with the blur of an old CRT, and it looks better than it has any right to. Just note that you need to have the right EGA card, as some blocked the 16-colour modes when set to output IRGB/CGA– he used a Trident card to good effect. The software here, though, was just Deluxe Paint, which can’t stop winning, even after four decades.
The hack seems simple enough, and perhaps everyone knew about it back in the day, but this is the first time seeing it for this author. So we’ll leave it to the comments: have you ever seen a 5-display Commodore, or 4-screen EGA output done like this?
Of course CGA had some competition back in the 80s, and it would be fun to see how many retro standards this trick would work on; at the end of the video [The 8-Bit Guy] discusses splitting VGA signals, but that’s only three screens and way too new for him. If one of you takes up his challenge, please let us know.
