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rallyrabbit

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About rallyrabbit

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    Space Invader

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  1. Oh my, this is news. And actually changes my approach. This is exactly why I've been looking for schematics and stuff what replacements to see what to do. None of the new homebrew cartridges are 4k, so people are doing this somehow. Defender Arcade is a prime example (F8SC), so obviously others have done this..... how? So, either use that from a Stargate or Defender Cart? What do new homebrew people use here? Update, I just read about the Melody Board.... maybe that is the right path? I'd never heard of the Harmony until I ran across it yesterday, which then lead me to the Uno. SO thanks for that idea too.
  2. Nice changes, I am working through what you did vs I did now. It's close. Right now with the original code (where I no longer show mountains), Stella is indicating that it is outputting at a solid 60hz. However, once I've started adding changes (mine and your) I start seeing some random points where it drops to 59hz or up to 61hz. It isn't constant, but I also haven't isolated the exact situations causing it either. Once I get that sorted i'll post another assembly file. Also, how do you assembly you source? Every time I attempt it is 2 bytes too big.
  3. Hi all, Is there a master list somewhere of the type of PROM that games require. For instance, a lot of games are 4k. Some are 8K, but I have seen a ton of different schematics of 8k cartridge board with page switching techniques. Further, some add external RAM on the cartridge board too. I know I am asking for a specific example which is Atari 2600 Stargate/Defender II. 1) Does anyone make a PCB For this or have a layout/schematic for it 2) Suggestions on the 8K chip to use that performs the proper bank switching correctly 3) What external RAM chip to use 4) Schematic for how to lay this out so I can try and make one In my example, I'm making a hack/game but have no real way to test on a unit without going and killing a Defender II/Startgate cartridge, but this doesn't help me make more than 1. Kinda wondering, what do people do here?
  4. Looking through it and comparing. One thing I found in your demo code was that before the DEY before LF42A, these lines are needed otherwise the stars on the first iteration of index Y of play area will be more like lines instead of dots (STA NUSIZ1 is not though): AND #$F0 ;2 STA CTRLPF ;3 Still going through the rest to see how to apply, clean it up....
  5. After a week digging I thought I would post. I disassembled stargate and made some of the improvements from the Defender II hack that was done years ago. I'm also trying to do a number of other things. I'm fairly confident I've isolated a handful of portions of the code doing certain things (particularly scoring, graphics are not that hard). What I am trying to find now are two things that I am falling flat on: 1) I am trying to find the routine (supposing it is timer based) that uses multiple graphics to rotate for the enemies. There are enemies that have 3 graphics each and seem to rotate through on a strict timer interval 2) I am trying to figure out where the mountains are generated to start playing with that as well. I thought these would be a predetermined set of "graphics too" but I think I am wrong. Putting up the set of assemblies just in case someone can offer some assistance. defender-arcade_1.asm defender-arcade_2.asm
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