Subject: [stella] That .byte thing From: John K Harvey <jkharvey@xxxxxxxxxxxxxxxxx> Date: Thu, 24 Sep 1998 19:39:24 -0500 |
Ok, I'm hooked. I finally can start programming for 6502 and this is good for me, but they are probably a lot of standard or inane questions which are too easy to contemplate. Well, here goes. I now have playfield and background stuff mostly figured out. I want to draw an X on the background using the Player0 graphic. I have some problems. I do not know how to do that .byte thing and when I do it the hard way (see below) I require 2 STA WSYNCs in order to see something draw on the screen. Will the .byte command help me out? Here is the subroutine from the main drawing function. The accumulator is counting down for each scanline. That is why I transfer it to X. PLAYER_DRAW: TAX LDA #$C3 STA GRP0;put numbers in STA RESP0;set for print STA WSYNC;why does nothing print here? STA WSYNC;2 here works fine, but only one draw LDA #$66 STA GRP0 STA RESP0 STA WSYNC STA WSYNC LDA #$3C STA GRP0 STA RESP0 STA WSYNC LDA #$18 STA GRP0 STA RESP0 STA WSYNC LDA #$18 STA GRP0 STA RESP0 STA WSYNC LDA #$3C STA GRP0 STA RESP0 STA WSYNC LDA #$66 STA GRP0 STA RESP0 STA WSYNC LDA #$C3 STA GRP0 STA RESP0 STA WSYNC LDA #0;delete all graphics now STA GRP0 TXA;reset accumulator SBC #10;subtract scanlines used JMP RETURN ;back to main Thanks. I know this is probably boring stuff, but I'm trying to learn it, and there's a LOT to learn. -John K. Harvey http://www.cae.wisc.edu/~harveyj -- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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