On 26 April 2011 16:58, Chris Pile <[email protected]> wrote:
> I'm not sure having only a basic ability to shift the screen around would > have been much use without > additional hardware support. Such as sprites for example. Having to > render lots of software sprites > over nothing more than a shiftable 24k lump of RAM would get very messy > code wise. Especially > with the need for double-buffering to avoid glitching/flicker, Etc. > I don't understand this. You're saying that, because doing it with the help of a movable background would still be hard, we should be grateful that they didn't lumber us with the challenge to try to write it? Not to mention the poor old Z80 would still have a shedload of work to do > shunting the required data > around. Any scrolling game running at less than 50-fps with only > half-a-dozen or so on-screen entities > really wouldn't be worth the effort! Really? From memory most scrolling shoot-em-ups have a limited number of moving baddies at any one time. And most of the baddies move with the scroll, because the scroll is meant to represent the hero flying through the scenery... so the only thing you have to worry about is the Hero. > Fast shoot-em-ups are awful at anything less than TV frame-rates. > Ever played Wings of Death on the ST? One of the best shoot-em-ups I ever played, and the background moves slowly. I guess that's because the ST didn't have scroll hardware either, so they had to do chunks at a time. Difference being, the ST had the power to do the scroll (probably at about 5fps, from memory) and the baddies too. I doubt if the Sam can do that. Maybe it could - I guess if you move the whole screen once every 10 frames, that leaves you about half your processing power. Even slow Z80-based systems such as the Master System managed to do > full-colour, full-screen 50-fps > scrolling with full-colour sprites (albeit in limited numbers) over the > top. But then it did have a tile-based > system for the background which, although (for the most part) it is more > limiting than a true bitmap, it did > mean the Z80 had very little work to do to maintain a nice scrolling > backdrop. > > Besides, there's something *pure* about having a chunk of RAM and a CPU - > and not much else! > Oh sure, if you don't cripple your CPU. G
