Subject: Re: [stella] What I've got so far From: gentlben@xxxxxxxxxxxx Date: Sat, 10 Jul 1999 05:40:54 -0700 |
> Forgive me for asking so many questions, but you guys explain things so > much clearer than the Stella manual. yeah, there are some things that the stella manual doesn't explain very well...just wait until you begin to work on horizontal positioning of the players and missiles and ball! <evil laughter>...but seriously, it is still nice to have the stella document :) > So I would start the program with: > LDA #$02 > Because this hex number, when tranlated to binary, is 00000010 and bit > 1 at memory location $0000 starts VSYNC, and I next: > STA $0000 > Once that is done, I can put a couple of commands in, to blank out some > memory or something. After a few commands, I would: > WSYNC > Then I can put a couple of other things here if I want, or just leave > it blank and immediately: > WSYNC > Then I do whatever it was again and: > WSYNC > That will make the third scanline for the VSYNC. I then: > LDA #$00 > STA $0000 > Which turns off the VSYNC and then I start working on the VBLANK area, > right? (Not to repeat everything gentlben wrote, I just want to make > sure I have the logic right.) writing $02 to the register VSYNC would begin vertical sync, yes. but may i suggest just using two zeroes instead of four when writing to the TIA registers, since they are all within $0000-$00FF? and to start writing VBLANK you turn it on the same way you turned on VSYNC, but this time, write to $01. also, if you want to do stuff like blank out memory or other important initialization things (like setting flags and clearing registers), ive found that most programmers simply do that at the beginning of the program, then when all that is done, begin VSYNC and VBLANK...but during VSYNC and VBLANK, you have about 40 scanlines worth of free cycles to do whatever you wish...but if you dont want to do anything at all, just WSYNC through the scanlines... btw, ive been trying to get the stella mailing list to show me as something other than gentlben...i sign almost all the email i write to this list with 'dee' :P > So VBLANK just sends out whatever color is in the background register > at that time, huh? Could come in very handy. but VBLANK wont display anything on the screen... not the background or the playfield or any of the neat little moveable objects. you have to actually get to the picture lines before anything will be shown...at which point VBLANK is turned off and you begin to really code :) > I'll have you know if you shoot me with a drugged dart, I'll...well, > I'll be very happy, but that's beside the point! ;-) true :) i know there are times i could have used a nice quiet snooze but couldnt get one... dee -- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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