jonmower

I have been working through the introductory exercises, and am now programming my own backgrounds and playfields using Andrew Davies' book. Is there a good resource for continuation of the education? I am starting from scratch--I have never programmed before this, so I am going to need information on how to use the joysticks, how to program sound, and etc. Let me know! Matt

Thanks, Moonsweeper. I was able to complete the task by putting the PF1 inside the loop. I appreciate it.

Thanks, Moonsweeper. I have played with the Nops, but I am still getting symmetry. In the above code, where should I stick the Nops and PF1 =0?

Dear Forum Members: I have been following the Andrew Davie Tutorial on Randomterrain.com . I think that it is very well written. Essentially, I am learning assembly language from scratch. I have three questions that I hope that you may be able to help me with: 1. The code below is from an Excercise in chapter 13 : Playfield Basics. I have been able to complete the exercise making the playfield rainbow striped vs. the background. However, in achieving the effect, I believe that I have unnecessary code, which apparently is a 'no-no' in Atari programming because of the limitations. What unnecessary code can I take out below to make the solution still work? 2. The last exercise in this section asks, how do you make the Stripe appear on one side and not the other? It hints that you have to change the playfield mid-scanline. I do not know how to do this, but I think that it will be explained in a later chapter. Anyone have a very concise explanation? I have a renewed appreciation for early video game programmers after going through the first 13 chapters! Any and all help is greatly appreciated! ------------------------------------------------ ; ; My VCS Game ; by Author ; ; VCS template file by Ian Bogost ; http://www.bogost.com ; ;------------------------------------------------ processor 6502 include vcs.h include macro.h ;------------------------------------------------------------------------------ PATTERN = $80 ; storage location (1st byte in RAM) TIMETOCHANGE = 1 ; speed of "animation" - change as desired ;------------------------------------------------------------------------------ SEG ORG $F000 Reset ; Clear RAM and all TIA registers ldx #0 lda #0 Clear sta 0,x inx bne Clear ;------------------------------------------------ ; Once-only initialization... lda #%11111111 sta PATTERN ; The binary PF 'pattern' lda #$54 sta COLUPF ; set the playfield color ldy #0 ; "speed" counter ;------------------------------------------------ StartOfFrame ; Start of new frame ; Start of vertical blank processing lda #0 sta VBLANK lda #2 sta VSYNC sta WSYNC sta WSYNC sta WSYNC ; 3 scanlines of VSYNC signal lda #0 sta VSYNC ;------------------------------------------------ ; 37 scanlines of vertical blank... ldx #0 VerticalBlank sta WSYNC inx cpx #37 bne VerticalBlank ;------------------------------------------------ ; Handle a change in the pattern once every 1 frames ; and write the pattern to the PF1 register iny ; increment speed count by one cpy #TIMETOCHANGE ; has it reached our "change point"? bne notyet ; no, so branch past ldy #0 notyet lda PATTERN sta PF1 ; as the playfield shape ;------------------------------------------------ ; Do 192 scanlines of color-changing (our picture) ldx #0 ; this counts our scanline number Picture ; change background color (rainbow effect) sta WSYNC ; wait till end of scanline stx COLUPF inx cpx #192 bne Picture ;------------------------------------------------ lda #%01000010 sta VBLANK ; end of screen - enter blanking ; 30 scanlines of overscan... ldx #0 Overscan sta WSYNC inx cpx #30 bne Overscan jmp StartOfFrame ;------------------------------------------------------------------------------ ORG $FFFA InterruptVectors .word Reset ; NMI .word Reset ; RESET .word Reset ; IRQ END

Thanks! You guys are really helpful. Also Andrew emailed me back.

Hello: I have been learning Atari 2600 programming on my Mac. I have read the beginner information online, and am able to program simple things such as colors and objects. I have also been hacking code and changing things. I am having difficulty understanding or finding resources on some commands at the beginning of the programs which I have hacked. For example, I know that STARTSCREEN changes the bottom position of the screen because I have changed its value and have observed it. However, I haven't found a resource which lists this command and what the variable represent. I know that one game starts at $54. Here are other commands which I do not have a solid definition for: NTSC = 0 PAL = 1 COMPILE_VERSION = NTSC ; Position equates SCREENSTART = $54 UP = SCREENSTART DOWN = $04 LEFT = $02 RIGHT = $A0 SCOREOFFSET = $31 MAXSCORE = $42 There is also code at the beginning of PITFALL such as SCREEN_SAVER, TRAINER FILLOPT, etc. Is there a reference guide for these commands? Thanks!

Hello: I have been learning Atari 2600 programming on my Mac. I have read the beginner information online, and am able to program simple things such as colors and objects. I have also been hacking code and changing things. I am having difficulty understanding or finding resources on some commands at the beginning of the programs which I have hacked. For example, I know that STARTSCREEN changes the bottom position of the screen because I have changed its value and have observed it. However, I haven't found a resource which lists this command and what the variable represent. I know that one game starts at $54. Here are other commands which I do not have a solid definition for: NTSC = 0 PAL = 1 COMPILE_VERSION = NTSC ; Position equates SCREENSTART = $54 UP = SCREENSTART DOWN = $04 LEFT = $02 RIGHT = $A0 SCOREOFFSET = $31 MAXSCORE = $42 There is also code at the beginning of PITFALL such as SCREEN_SAVER, TRAINER FILLOPT, etc. Is there a reference guide for these commands? Thanks!