Forum Index | FAQ | New User | Login | Search

Make a New PostPrevious ThreadView All ThreadsNext Thread*Show in Threaded Mode


Subjectmaking a 6502 emu: port or write from scratch, and which system first? Reply to this message
Posted bynewsdee
Posted on02/06/05 11:02 PM



I'm thinking of start playing with a 6502 emu in actionscript (Flash). I don't plan on actually starting until I complete my Chip8 emulator and come up with a better/faster display mode (getting there), but I'm starting to wonder about the best way to go.

I'd like to program an Apple II emu since I still own the actual machine (so mad nostalgia bonus), but I think it may be still a little outside of my league.

I'm thinking that maybe an Atari emu would be a good stepping stone, since its processor is apparently a simpler version of the 6502. Granted, I'd have to emulate the VCS which has nothing to do with the Apple II, so there would be some specific development anyway.

I'm not worried about sound, because there is not (so far) any way to precisely control sound in Flash. Graphics would be the biggest issue but I think, in the worst case, I can pull off text mode for the Apple II and a monochrome display (useless for most games) in the Atari. The next version of Flash may have pixel manipulation, so if I have the code ready it would be an easy switch.

The other consideration is if I should port somebody's core or just write from scratch. The latter would take more time, be poorly optimized at first, but would be ultimately more gratifying and fun. I guess the 6502 is documented enough to allow me to write my own stuff.

Well, so there it is... what do you think?
I know the world doesn't need another Atari or Apple emu, and that Flash is really not a language for emus (yet), but it's just for fun :-)




[download a life]


SubjectRe: making a 6502 emu: port or write from scratch, and which system first? new Reply to this message
Posted bysmf
Posted on02/07/05 03:03 AM



any atari machine is going to be more of a pain to emulate than an apple.

smf





SubjectRe: making a 6502 emu: port or write from scratch, and which system first? new Reply to this message
Posted byfinaldave
Posted on02/07/05 09:21 AM



> I'm thinking of start playing with a 6502 emu in actionscript (Flash). I don't
> plan on actually starting until I complete my Chip8 emulator and come up with a
> better/faster display mode (getting there), but I'm starting to wonder about the
> best way to go.
>
> I'd like to program an Apple II emu since I still own the actual machine (so mad
> nostalgia bonus), but I think it may be still a little outside of my league.
>
> I'm thinking that maybe an Atari emu would be a good stepping stone, since its
> processor is apparently a simpler version of the 6502. Granted, I'd have to
> emulate the VCS which has nothing to do with the Apple II, so there would be
> some specific development anyway.
>
> I'm not worried about sound, because there is not (so far) any way to precisely
> control sound in Flash. Graphics would be the biggest issue but I think, in the
> worst case, I can pull off text mode for the Apple II and a monochrome display
> (useless for most games) in the Atari. The next version of Flash may have pixel
> manipulation, so if I have the code ready it would be an easy switch.
>
> The other consideration is if I should port somebody's core or just write from
> scratch. The latter would take more time, be poorly optimized at first, but
> would be ultimately more gratifying and fun. I guess the 6502 is documented
> enough to allow me to write my own stuff.
>
> Well, so there it is... what do you think?
> I know the world doesn't need another Atari or Apple emu, and that Flash is
> really not a language for emus (yet), but it's just for fun :-)
>
>
>
>
> [download a life]
>

Which is easier, Apple II or C64? (Or even NES?)


Newsdee's Love, Glory, and Discussion Boards



SubjectRe: making a 6502 emu new Reply to this message
Posted byR. Belmont
Posted on02/07/05 04:50 PM



> any atari machine is going to be more of a pain to emulate than an apple.

That depends - the Atari has nastier audio/video hardware, but the Apple II is bankswitched like a mofo. Neither are particularly great for first-timers. I would instead suggest some of the early Atari 6502 arcade games like Super Breakout.




Subjectatari arcade new Reply to this message
Posted bynewsdee
Posted on02/07/05 09:58 PM



> That depends - the Atari has nastier audio/video hardware, but the Apple II > is bankswitched like a mofo. Neither are particularly great for first-
> timers.

I guess in that case I should rather port an existing emu...

> I would instead suggest some of the early Atari 6502 arcade games
> like Super Breakout.

I thought about Atari vector games, because they should go well with Flash's vector engine. However I'm concerned about game availability. I'd like my emu to include at least one public domain game, but I don't think there's anything public domain for Atari arcade hardware. I have developed a small way to import data from any files (so you could enter a link to a ROM to load it, from an external site), but I'd still like the emu to have *something* in it when booting it up. Is there some PD diagnostic program for it or something?

I also thought about Vectrex but the internals of that system seem more obscure than a Chinese book on compiler optimization.




[download a life]


SubjectRe: making a 6502 emu: port or write from scratch, and which system first? new Reply to this message
Posted byJonemaan
Posted on02/08/05 08:56 AM



Hmm, coincidentally again, i wrote a 6502 cpu core a few days ago, and found it to be pretty easy. It only has fiftysomething official opcodes.

Like others say, it matters what you want to do with it. I'm (trying to) make a simple NES emu. I'd go for the AppleII if i were you, since you can test effects on the original machine (or doesn't it have some sort of built-in Basic/ASM?)






Subjecthaw - nice coincidence new Reply to this message
Posted bynewsdee
Posted on02/08/05 09:04 PM



> Hmm, coincidentally again, i wrote a 6502 cpu core a few days ago, and found > it to be pretty easy. It only has fiftysomething official opcodes.

Heheh how about that. I agree, it doesn't seem much more complex once you write something to handle the variable addressing (I guess; I didn't start writing yet).

> I'd go for the AppleII if i were you, since you can test effects
> on the original machine (or doesn't it have some sort of built-in Basic/ASM?)

Actually the other reason I'm thinking of the AppleII is that its display is monochrome. It had color but it was some kind of trick (e.g. 0101 -> 2 red pixels, 1010 -> 2 purple pixels). So I think I can just do everything monochrome at first then worry about the rest. The only bottleneck would be handling the resolution.

So I guess I should first attempt to have a moderately fast updating monochrome screen of the dimensions of the Apple ][ screens (this is a no brainer with most languages, just Flash sucks for this).




[download a life]


SubjectRe: making a 6502 emu new Reply to this message
Posted bysmf
Posted on02/09/05 01:33 PM



I'd take bank switching on a machine I have access to over atari graphics chips any day.

VIC 20 is possibly a good contender though for a "my first emu" project.

smf





SubjectSuper Breakout info? new Reply to this message
Posted byCabaretVoltaire
Posted on03/09/05 03:13 PM



Where could I get some technical info on Super Breakout (or similarly easy to emulate hardware)? I've got the mame source but as a beginner a don't really know where to start with it (I've found the sbrkout drivers and everything but don't fully understand what I'm looking at)

Thanks




SubjectRe: atari arcade new Reply to this message
Posted byAlphasys
Posted on02/26/08 01:45 PM



I'd suggest looking for Atari800winPLus. It has sourcecodes and is the best working atari 8-bit emulator I've ever encountered.




Previous ThreadView All ThreadsNext Thread*Show in Threaded Mode