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DEBRO last won the day on March 21 2010

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    Atari game programming

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  1. Hi Jeff, This is an excerpt from the Atari 2600 TIA Hardware Notes by Andrew Towers...
  2. Hi Jeff, First the value $C0 is a +4 pixel adjustment. Looking at the routine, I could be wrong, but I don't think the extra cycle is needed to position the players. If you were to use a value of 0, the routine in its current state would coarse position the player to pixel 69 with a fine adjustment of $60 or -6. This places the player at pixel 63. Adjusting for HMOVE (i.e. +8 pixels) would place the player at pixel 71. If the extra cycle were removed from the HMP0,x hit then the player would coarse position to pixel 66 with a fine adjustment of the same -6 and place the player at pixel 60. Adjusting for HMOVE would then place the player at pixel 68.
  3. DEBRO


    Hi Andrew, Thank you for sharing. I look forward to looking through this. Boulder Dash(TM) is an impressive masterpiece.
  4. Hi there, I'm curious as to how you have these ROMs. They were only produced for the Flashback units. I can say there is a PAL50 version of Yar's Return unfortunately, I cannot share it. We anticipated Atari needing these for a PAL version of the FB2 but that never happened. The PAL50 version not only adjusts the timing and colors but also adjusts the kernel where there is a top and bottom Neutral Zone.
  5. Hi there, Thank you. My hope is that it makes sense and that the comments come close to what the original engineer had in mind. These can never replace original source code with the original comments but hopefully it helps. There is a list of disassembled games done by me and others on Bjars.com. I have plans to have an archive site of all my work one day...one day. There is also this list in the "Disassembling 2600 Games?" thread that I update and edit. The crossed out items point to links of threads. I agree. Not something I had in the '80s but it is actually a fun game. It also looks to be a nice game done in AtariBASIC for the A8. It would have made for a really great type-in game / clone in magazines like Antic, ANALOG, or COMPUTE! I like how Dave used HMOVE values and NUSIZ to construct the shark. I also like the use of slope or linear equation for the fishing line. I guess its touches like this that make his projects stand out. I use an encoding of ANSI. Those may be the 3 exponent used in the kernel for branch instruction cycle counting.
  6. Hi there, I had planned to attend PRGE this year but won't be able to make it. My nephew is planning to attend. I asked him to stop by the AtariAge booth to introduce himself.
  7. Hi there, Another David Crane Activision game. Enjoy. Fishing_Derby.zip
  8. DEBRO


  9. Hi Brian, Thanks...heading to do some "DuckDuckGo"-fu
  10. Hi Albert, Whew...thought I was slipping. Thanks.
  11. Hi there, Darrell mentioned to me on Twitter that he was thinking of starting a group when he finds free time. In the meantime, I thought I'd browse on the topic and was surprised not to find anything. My Google-fu or AtariAge-fu may be lacking over the years. I don't find any topics when I search for 'ARM' in this forum. With all the ARM development going on are there no topics in the forum?
  12. How do others get this privilege 😉
  13. Hi there, I hacked up a PAL50 version to adjust the vertical position velocity by 1.2. I had to fudge the values for level 3 and 4 as they would have been more the 255. Still (in Stella) the velocities look to be accurate with the NTSC version. The issue though is that Potsy's horizontal movement does not accommodate for the change. This makes the game slightly difficult for the PAL50 version.
  14. Hi there, The PAL50 ROM I have is labeled (Unknown)(PAL) and appears to be a bootleg or hack instead of an official release. It has the Activision copyright removed and doesnt adjust the colors for the PAL region. Was this ever officially released in the PAL region by Activision? Im curious if its implementation if one does exist. Activision was known for adjusting the screen and colors to fit PAL50 TVs. All reverse-engineering projects show timing or fractional positioning wasnt used. Crackpots however does have fractional positioning for the bugs vertical movements. I was curious if they adjusted these values to accommodate for the PAL50 refresh rate.
  15. Hi there, Thanks for sharing. I can't say enough good things about Thomas. He has worked with a number of use 2600 homebrewers. I couldn't do what I do without his help and guidance. He is a great and patient mentor. It would be wonderful to have a revisit of Stella @ 20...(e.g. Stella @ 45?) and have Thomas interviewed. He has contributed heavily to the 2600 homebrew scene.
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