+Atarius Maximus Posted March 12, 2004 Share Posted March 12, 2004 Well, here's my first stab at writing a program for the 2600. It's a little program that lets you move a ship in all four directions around the screen. Weeeee! Ok, it's not much fun, but it's a start. I'm going to try and add a few things to it, maybe make the ship fire a missle, and add something to shoot at! It's been a little while since I started working on this...I seem to remember piecing some of this info together from a tutorial on the internet, I can't exactly remember where it was though. Anyway, the bin is attached at the bottom of this post. processor 6502 include vcs.h org $F000 YPosFromBottom = $80 VisibleShipLine = $81 ShipBuffer = $82 Start SEI CLD LDX #$FF TXS LDA #0 ClearMem STA 0,X DEX BNE ClearMem LDA #$00 STA COLUBK LDA #$1C STA COLUP0 LDA #80 STA YPosFromBottom MainLoop LDA #2 STA VSYNC STA WSYNC STA WSYNC STA WSYNC LDA #43 STA TIM64T LDA #0 STA VSYNC LDA #%00010000 BIT SWCHA BNE MoveDown INC YPosFromBottom MoveDown LDA #%00100000 BIT SWCHA BNE MoveUp DEC YPosFromBottom MoveUp LDX #0 LDA #%01000000 BIT SWCHA BNE MoveLeft LDX #$10 LDA #%00001000 STA REFP0 MoveLeft LDA #%10000000 BIT SWCHA BNE MoveRight LDX #$F0 LDA #%00000000 STA REFP0 MoveRight STX HMP0 WaitForVblankEnd LDA INTIM BNE WaitForVblankEnd LDY #191 STA WSYNC STA HMOVE STA VBLANK ScanLoop STA WSYNC LDA ShipBuffer STA GRP0 CheckActivateShip CPY YPosFromBottom BNE ActivateShip LDA #8 STA VisibleShipLine ActivateShip LDA #0 STA ShipBuffer LDX VisibleShipLine BEQ FinishShip IsShipOn LDA ShipGraphic-1,X STA ShipBuffer DEC VisibleShipLine FinishShip DEY BNE ScanLoop LDA #2 STA WSYNC STA VBLANK LDX #30 OverScanWait STA WSYNC DEX BNE OverScanWait JMP MainLoop ShipGraphic .byte #%10000000 .byte #%11100000 .byte #%01111000 .byte #%11111110 .byte #%11111110 .byte #%01111000 .byte #%11100000 .byte #%10000000 org $FFFC .word Start .word Start movingship.zip Quote Link to comment Share on other sites More sharing options...
Thomas Jentzsch Posted March 12, 2004 Share Posted March 12, 2004 Works good. Just make sure to display one more scanline (currently 261) so that it will show some colors on PAL TVs too. Quote Link to comment Share on other sites More sharing options...
+Atarius Maximus Posted March 13, 2004 Author Share Posted March 13, 2004 Works Good. That means alot coming from you! Thanks. I'll be working on it a little more this weekend, I'll update my results in a few days. Just make sure to display one more scanline (currently 261) so that it will show some colors on PAL TVs too. Heh, just shows I'm a complete newbie at this. I'll attempt to figure that out on my own, but tips are always welcome. AM Quote Link to comment Share on other sites More sharing options...
Nukey Shay Posted March 13, 2004 Share Posted March 13, 2004 You are already better at this than me Quote Link to comment Share on other sites More sharing options...
Saikyo Posted March 13, 2004 Share Posted March 13, 2004 keep this up and before you know it you will have your very own R-Type style game! Quote Link to comment Share on other sites More sharing options...
+Atarius Maximus Posted March 16, 2004 Author Share Posted March 16, 2004 Progress is slow. I've read through the Stella programming guide, but at my current level of skill, it doesn't explain things very well. I did figure out one thing though...Now when you press the joystick button, it places a vertical line on the screen that never disappears. At least I got it to do something! processor 6502 include vcs.h org $F000 YPosFromBottom = $80 VisibleShipLine = $81 ShipBuffer = $82 Start SEI CLD LDX #$FF TXS LDA #0 ClearMem STA 0,X DEX BNE ClearMem LDA #$00 STA COLUBK LDA #$1C STA COLUP0 LDA #80 STA YPosFromBottom MainLoop LDA #2 STA VSYNC STA WSYNC STA WSYNC STA WSYNC LDA #43 STA TIM64T LDA #0 STA VSYNC LDA #%00010000 BIT SWCHA BNE MoveDown INC YPosFromBottom MoveDown LDA #%00100000 BIT SWCHA BNE MoveUp DEC YPosFromBottom MoveUp LDX #0 LDA #%01000000 BIT SWCHA BNE MoveLeft LDX #$10 LDA #%00001000 STA REFP0 MoveLeft LDA #%10000000 BIT SWCHA BNE MoveRight LDX #$F0 LDA #%00000000 STA REFP0 MoveRight STX HMP0 LDA INPT4 BMI ButtonNotPressed LDA #2 STA ENAM1 LDA #33 STA COLUP1 LDA #$20 ButtonNotPressed WaitForVblankEnd LDA INTIM BNE WaitForVblankEnd LDY #191 STA WSYNC STA HMOVE STA VBLANK ScanLoop STA WSYNC LDA ShipBuffer STA GRP0 CheckActivateShip CPY YPosFromBottom BNE ActivateShip LDA #8 STA VisibleShipLine ActivateShip LDA #0 STA ShipBuffer LDX VisibleShipLine BEQ FinishShip IsShipOn LDA ShipGraphic-1,X STA ShipBuffer DEC VisibleShipLine FinishShip DEY BNE ScanLoop LDA #2 STA WSYNC STA VBLANK LDX #30 OverScanWait STA WSYNC DEX BNE OverScanWait JMP MainLoop ShipGraphic .byte #%10000000 .byte #%11100000 .byte #%01111000 .byte #%11111110 .byte #%11111110 .byte #%01111000 .byte #%11100000 .byte #%10000000 org $FFFC .word Start .word Start movingship2.zip Quote Link to comment Share on other sites More sharing options...
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