Sphere 6502 emulator

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Re: Sphere 6502 emulator

Reply #15 – September 14, 2016, 11:22:35 am

Not sure if you're still playing around with this but I just had a random thought -- the NES and SNES run off of modified 6502 chips. Would it be possible to program an emulator in Sphere if this got up and running?

Re: Sphere 6502 emulator

Reply #16 – September 15, 2016, 06:02:41 am

This is just a basic MOS 6502 emulator, the cpu itself with some stuff for drawing and taking input. For NES emulation, you also need to add code to handle palletes, sprite data, tile data and much more. And while the SNES's CPU is based on the 6502, that would take even more work.
Either way, it definitely wouldn't be at all impossible, but this would end up being a very small fraction of the overall code.

Re: Sphere 6502 emulator

Reply #17 – September 15, 2016, 01:03:56 pm

I will go ahead and say that for anything resembling accurate SNES emulation, JS (or really almost any non-native language) is just way too slow. The NES may be another matter, though.

Re: Sphere 6502 emulator

Reply #18 – September 15, 2016, 03:32:11 pm

Why is that? There's an x86 virtual machine written in Javascript, and while it obviously doesn't perform as well as it would natively, the x86 instruction set is a lot more complex than the SNES's CPU's instruction set.

Re: Sphere 6502 emulator

Reply #19 – March 19, 2018, 08:48:36 pm

Making a new thread when this one is still on the first page seems kind of pointless, so I'll just resurrect this one.
Like how I've resurrected the 6502asm.com -> miniSphere port! And it actually (sort of) works this time, though rendering is kind of sluggish.

It also has a ROM hexdump function.

Re: Sphere 6502 emulator

Reply #20 – March 19, 2018, 09:03:35 pm

I’m intrigued and looking forward to seeing more.

Re: Sphere 6502 emulator

Reply #21 – March 20, 2018, 08:52:49 pm

Aaand done. Thanks for the help, Fat Cerberus and rhuan!

Re: Sphere 6502 emulator

Reply #22 – March 21, 2018, 12:03:22 am

This is a pretty awesome little assembler/emulator, me likey. :smiley: Is there a specific device this is meant to emulate?

Re: Sphere 6502 emulator

Reply #23 – March 21, 2018, 12:44:16 am

As far as I know, it isn't meant to emulate a specific system, and it doesn't have interrupts for input. ASCII values from keypress events are written to memory location $ff, and Math.random()*255 is written to memory location $fe, and for graphics, you simply read from/write to $200-$600 (1 KB or 32x32 px)

Re: Sphere 6502 emulator

Reply #24 – March 22, 2018, 09:14:22 am

This is very neat. I played a little bit of adventure.asm.

I guess in a way this adds compatibility to a whole bunch of (simple) games to miniSphere all at once!

Re: Sphere 6502 emulator

Reply #25 – March 25, 2018, 12:56:58 pm

Glad I could help - I'm almost always happy to spend time optimising code

Nice to see this running smoothly at high FPS now.