Subject: [stella] Now I've got it!!!! Sorry gang! From: crackers@xxxxxxxxxxxxxxxxxxxxxx Date: Sun, 9 Mar 1997 02:24:13 -0500 (EST) |
Okay, I found out why my programme wouldn't draw a picture on a real 2600. It wasn't completing the Vertical Blank properly because of a typo. This is the way the verticle blank subroutine should look. ----------------------------------------------------------------------------- vertb LDX #$00 ;thank you Nick Bensema for teaching us all LDA #$02 ;how to do a vertical blank. STA WSYNC ;who knows if I could have figured out this one STA WSYNC ;on my own. I want to have your baby! STA WSYNC STA VSYNC ;<- here was one of my 5:00 in the morning errors. STA WSYNC ;I had typed WSYNC instead of VSYNC. Bleary eyes STA WSYNC ;and programming make a deadly combination! LDA #$2C STA TIM64T ;much like cheese burgers an loneliness. LDA #$00 STA CXCLR ;<- don't know why I left this in... but what the STA WSYNC ;heck it looks cute. STA VSYNC ;**********CHANGED CODE FROM ORIGINAL************** RTS ;had made another stupid 5am error. (STA WSYNC) ----------------------------------------------------------------------------- In my original code that last line before the RTS read... STA WSYNC Be very careful when writing code. That's twice in the same programme (in the same sub routine) that I've made that typo. And it's not an easy typo to catch either because it looks like proper code unless you pay attention. It also brings up another point. The Atari PC Emulator didn't crash on this error like a real 2600 did. Why? In anycase, from now on I'm not just going to take the Emulator's word for it that a programme works. I'll be sure to double check it on a real Atari 2600. Sorry about all the mess. If you're using the code be sure to change the line to the proper one. Man... it's something else to see a screen drawn on a real live 2600 and be able to say "I made it do that!" I can't wait to see what I can make it do next! CRACKERS (One happy hacker from hell!!!) -- Accordionist - Wethifl Musician - Atari 2600 Collector | /\/\ http://www.freenet.hamilton.on.ca/~ad329/Profile.html | \^^/ Bira Bira Devotee - FES Member - Samurai Pizza Cats Fan| =\/= -- To unsubscribe, send the word UNSUBSCRIBE in the body of a message to stella-request@xxxxxxxxxxx
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