Subject: [stella] Phase Two From: Pete Holland <petehollandjr@xxxxxxxxx> Date: Sun, 21 Feb 1999 18:08:55 -0800 (PST) |
Howdy, gang. I think I have the general 6502 commands down. I'm now focusing on the Stella Programmer's Manual to see the specifics. Already, however, some questions occur to me. I have downloaded DASM, and when I finally get everything more or less together, I'm going to try to program a solitaire game, figuring that would be a good "test" to see if I grasp everything (or I'm I high?). Before I do, I have some questions. Please don't laugh if these seem obvious. I haven't really taken an in-depth programming class. 1) What is a "sprite"? From the hype around my SMS, NES, Genesis, and SNES, I was under the impression that a sprite is like a Colorforms sticker, an image that the computer can move around over the background. If that's right, how can the Atari, which, from my preliminary reading, needs to draw the entire screen, have sprites? Does it have sprites, or are they things that act like them? How much of this do I have wrong? 2) I'm having trouble grasping the concept of cycle counting. Is this how it works? The actual image the Atari draws is larger than the TV screen. The first forty lines don't appear, and while these are being drawn out, since they only need a single color like black and nothing pertinent to the game, this is where you have the CPU doing calculations regarding the game (movements, calculations, etc.). The next 192 lines are where the picture is drawn, and since the computer has to read the info, this is where you leave it alone to do its job. The next thirty lines are blank like the top forty, and more game decisions can be made here. How can you tell how much time you have to do these things? Do some commands take more time to execute than others, and if they do, how long so that you can make it do the calculations without disrupting the flow of the scan? 3) Please explain the concept of MHZ to me. From what I understand, a hertz is a single cycle, so a megaHertz would be a million cycles. The TV screen, according to the Stella manual, draws the picture sixty times a second. That makes sixty hertz, right? How do the "clock counts" work with the hertz, then? How many clock counts in a hertz? Who knows? With all these questions I'm asking, I may someday have enough that I can write the tutorial people are dreaming about. _________________________________________________________ DO YOU YAHOO!? Get your free @yahoo.com address at http://mail.yahoo.com -- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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