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Tom

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Posts posted by Tom


  1. Just don't forget: for an assembler to get any acceptance at least in the Atari 2600 community it needs to be DASM compatible (either by being compatible itself or by being powerful enough to make it able to compile DASM sources using macros or so).


  2. I'm writing it in Perl (I know, I know, but it's easier than C for me.)

     

    So what ? If I'll ever get around to writing my own assembler I'll write it in Ruby and make it somehow interpret Ruby code embedded into the source code.


  3. I've tried it on x86

     

    That's where gas sucks at for several reasons (stupid non-standard AT&T syntax, limited real mode support, ...).

     

    I've written quite a bit of ARM (ARM and Thumb) code with gas, both as inline assembly with gcc and standalone, and it's great. Seriously, before you go and write your own 68k assembler, try out gas and other available assemblers (don't know any from the top of my head that might be worth looking at).


  4. That's why I was asking. Binutils is no problem. Getting Binutils, GCC and a C Library to work however is a bit harder. And it gets really fun if you want your toolchain to compile C++ programs.

     

    Although I haven't used gas for writing 68k code I can only recommend it (except for writing x86 code. NASM is better for that).


  5. I love it. Had to find new hobbies, though, because since I'm not studying anymore but working as software developer I don't have the urge to work on software projects in my free time anymore (I used to spend a lot of time with that).

     

    Well, I picked up paragliding and am thinking about taking karate lessons.


  6. I have two PAL juniors. Looks like I have to dig them out. What I know is what works on at least one of them is achieving an 8 pixel left shift by triggering HMOVE out of specs. I think that was an experiment with a 12/24 char kernel that moved the sprites left/right per scanline.

     

    At least those consoles can be autodetected

     

    How so ?


  7. You get the HMOVE lines if you follow the stella manual and trigger HMOVE right at the start of a scanline. There are certain cycles (74 ?) where you can trigger HMOVE and get exact the same behaviour (same amount of movement for same HMxx value) without the HMOVE lines.

     

    See http://www.biglist.com/lists/stella/archiv...4/msg00198.html

     

    Does this work reliable on any 2600, btw ?

     

    There are also games that trigger HMOVE on every scanline, which results in a black border over the whole left of the screen. Still better than garbage moving around to the left of the screen, imo.


  8. In a perfect universe where one could bankswitch 1k or 2k boundaries a more complex set-up with the kernel code packed into a certain 1k bank and the other 3k switched might work, but it's an edge case for custom elecronics for a niche product as it is.

     

    There were commercial games that used such bankswitching schemes.

     

    Plus, the emulators would hate it. No need to introduce that much complexity, it's complex enough as it is.

     

    Nonsense. Last time I checked the z26 source looked as if it was fairly trivial to add new bankswitching schemes.


  9. Reverse engineering is the simpler the better you know the engineering bit without the reverse thingy. That said, I recommend looking at Andrews tutorial first. Looking at game source codes or disassembling games is good for learning advanced techniques. Reading Andrew's tutorial will also help you to spot common Atari 2600 programming idioms. This will greatly help you when you're actually ready to disassemble and analyze a game.


  10. Pardon my ignorance, I've heard of trackers before but I've forgotten what they are.

    They're programs to compose music, typically they have an interface like this : http://en.wikipedia.org/wiki/ScreamTracker (Scream Tracker was a fairly famous tracker that ran under DOS). The Amiga / PC trackers usually worked with sampled sounds, but for instance the C64 trackers of course use the SID.

     

    Are you talking about an editor on a PC to edit music for the 2600 (specifically for Pauls driver?)

    Yes. Several people have worked on such editors, including a friend of mine who made the sound for this intro : http://www.pouet.net/prod.php?which=13900. That editor has never really reached a usable state. First of all it doesn't optimize the tune (it allows you to enter duplicated patterns, which is ok, but it should optimize them away) and second it needs an emulator to play the sound, which is inconvenient.

     

    My idea was to use a standard MIDI editor that I already have (such as Steinburg Cubasis) and then write a tool to convert to 2600 format...  hmmm I just had an interesting thought. How about a TIA synth VST instrument for steinburg. I seem to recall that someone has already done one for the SID....

     

    It's neither hard to write a VST plugin nor is it hard to rip out the sound emulation part out of a 2600/7800 emulator (at least Stella and emu7800 are kept fairly modular), so that could probably be done quickly, although I think an editor that is tailored to Paul's music driver would be more useful.

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