The second the entire EGA screen smoothly panned left was the second that my entire reality was shattered. I was completely and utterly blown away. My brain was ruined, wiped out. I couldn’t work for the next 3 hours. It was just amazing. I knew the games available on the PC very well by this point (1990) and NO ONE had ever created a Mario-style smooth-scrolling game on the PC.
I’m sort of surprised by his reaction … but I know nothing of old school PC graphics. Surely scrolling wasn’t such a big deal in 1990? I played Mac games in the late ‘80s that scrolled in both X and Y, and at least one of those ran in color on a Mac II. Obviously Mac and PC were different markets with different hardware, but if a 68020 could do it at 640x480 in 8-bit color, surely it wasn’t hard for a 386 in 320x240 x4-bit?
It was a big, big deal: CGA cards of the 80s had to redraw the entire screen, and only with EGA (mid-80s, plus time to filter out to consumers) did you start to get enough hardware support to put together the same visuals at a tolerable speed that consoles had already been doing on their purpose-built hardware.
id’s subsequent Commander Keen was as good as PC scrolling got for a few years in the early 90s.
So, the original PC had two display options. The Monochrome Display Adapter (MDA), for people who wanted good-looking text but no graphics; and the Color Graphics Adapter (CGA), for people who wanted to be able to play games or do other graphical things. We’ll forget about MDA for obvious reasons.
CGA wasn’t made for smooth-scrolling. There was no hardware support, and access to video RAM was far too slow to do it the brute-force way — particularly on the original/genuine CGA, which only had single-port VRAM, so the CPU would be blocked from accessing VRAM any time the video card was reading from it to actually draw the screen. Those bus lockouts reduced the available bandwidth even more, and cost CPU time.
If you tried to update the whole screen each frame you would have a terrible framerate, so you didn’t. For something like a platformer you would have a few sprites moving around the screen, and each frame you would paint them, after repainting whatever background tiles were covered by sprites in the previous frame. With 90% of the screen not changing, you could ship a frame in a reasonable time. Scrolling would probably be a “full screen” scroll at the screen edge, and that would cause a little hitch, but the slowdown would be somewhere between unnoticed and welcome, because your eyes would be busy taking in the new scene.
The EGA, besides providing more colors and higher resolutions, could do smooth scroll, but it wasn’t exactly a headline feature, you had to be fairly clever to bring together the available tools smoothly. Abrash and Carmack were the clever people who pulled it off.
As for the Mac, I’m not super up on the details of that platform, and I’ve never seen a full-color full-motion game running on a Mac II but my understanding is that the video was a straight framebuffer (the card wasn’t doing anything particularly clever) but that access to that framebuffer was many times faster than it was with the CGA or EGA (which is probably a NuBus vs. ISA thing, and a 32-bit ground-up vs. 16-bit legacy thing). So the Mac presumably could afford the brute-force approach of just redrawing the whole screen a pixel to the left.
I didn’t realise at the time, because I’d mostly seen games on friends’ consoles, but it was impressive. Games like Captain Comic and Dizzy had a fixed background and moved a small number of things in the foreground. The graphics capabilities of early PCs were pretty limited: they were designed to run office applications, not games, and so they had a lot less graphics power than other home computers.
I’m sort of surprised by his reaction … but I know nothing of old school PC graphics. Surely scrolling wasn’t such a big deal in 1990? I played Mac games in the late ‘80s that scrolled in both X and Y, and at least one of those ran in color on a Mac II. Obviously Mac and PC were different markets with different hardware, but if a 68020 could do it at 640x480 in 8-bit color, surely it wasn’t hard for a 386 in 320x240 x4-bit?
It was a big, big deal: CGA cards of the 80s had to redraw the entire screen, and only with EGA (mid-80s, plus time to filter out to consumers) did you start to get enough hardware support to put together the same visuals at a tolerable speed that consoles had already been doing on their purpose-built hardware.
id’s subsequent Commander Keen was as good as PC scrolling got for a few years in the early 90s.
So, the original PC had two display options. The Monochrome Display Adapter (MDA), for people who wanted good-looking text but no graphics; and the Color Graphics Adapter (CGA), for people who wanted to be able to play games or do other graphical things. We’ll forget about MDA for obvious reasons.
CGA wasn’t made for smooth-scrolling. There was no hardware support, and access to video RAM was far too slow to do it the brute-force way — particularly on the original/genuine CGA, which only had single-port VRAM, so the CPU would be blocked from accessing VRAM any time the video card was reading from it to actually draw the screen. Those bus lockouts reduced the available bandwidth even more, and cost CPU time.
If you tried to update the whole screen each frame you would have a terrible framerate, so you didn’t. For something like a platformer you would have a few sprites moving around the screen, and each frame you would paint them, after repainting whatever background tiles were covered by sprites in the previous frame. With 90% of the screen not changing, you could ship a frame in a reasonable time. Scrolling would probably be a “full screen” scroll at the screen edge, and that would cause a little hitch, but the slowdown would be somewhere between unnoticed and welcome, because your eyes would be busy taking in the new scene.
The EGA, besides providing more colors and higher resolutions, could do smooth scroll, but it wasn’t exactly a headline feature, you had to be fairly clever to bring together the available tools smoothly. Abrash and Carmack were the clever people who pulled it off.
As for the Mac, I’m not super up on the details of that platform, and I’ve never seen a full-color full-motion game running on a Mac II but my understanding is that the video was a straight framebuffer (the card wasn’t doing anything particularly clever) but that access to that framebuffer was many times faster than it was with the CGA or EGA (which is probably a NuBus vs. ISA thing, and a 32-bit ground-up vs. 16-bit legacy thing). So the Mac presumably could afford the brute-force approach of just redrawing the whole screen a pixel to the left.
I didn’t realise at the time, because I’d mostly seen games on friends’ consoles, but it was impressive. Games like Captain Comic and Dizzy had a fixed background and moved a small number of things in the foreground. The graphics capabilities of early PCs were pretty limited: they were designed to run office applications, not games, and so they had a lot less graphics power than other home computers.
This is a nice piece of history to complement Masters of Doom, which is more focused on Carmack, Ramos, and Id.