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Two 6502 System
Posted: Wed Dec 22, 2021 12:27 am
by martinot
On 7/25/2021 at 9:09 AM, rje said:
While thinking about the 65c816, it struck me that, because 6502s are relatively cheap, a board could be made with two of them.
i tried to imagine WHY one would want to do this, and I’m not sure. I suppose one could handle graphics and sound while the other orchestrated the system. Maybe. That’s how graphics cards and sound cards work, right, except they don’t bother with a generic CPU.
I/O could perhaps be handled by one chip. The 6502 was embedded in the disk drives. But I’m not sure about that either.
it seems that it’s a solution looking for a problem. There already exist cheap ways to deal with each problem a small computer has.
Just idly thinking about what problems Another 6502 might be able to solve in general. It would of course not work with the X16 very well, since it would require a fundamentally different board architecture and not be the same computer.
I would much one 65c816 over two 6502. Gives more flexibility with a retro machine that can handle both 8-bit code and 16-bit code.
If it must strictly be an 8-bit machine, I would rather have a Z80 complementing the 6502. More flexibility in architecture and software that way!
Two 6502 System
Posted: Wed Dec 22, 2021 6:29 am
by Scott Robison
Why not two 65816? ?
Two 6502 System
Posted: Wed Dec 22, 2021 4:06 pm
by xanthrou
On 7/28/2021 at 10:30 PM, Gromit337 said:
As the OP said, from a technical point of view it's an interesting idea, but practically, it's just a solution looking for a problem to solve.
Back in 1979, Atari 8 bits had Antic, Pokey, CTIA/GTIA etc. But they were custom chips and each served a specific purpose. The same with their spiritual successor, the Amiga. Even Atari equipped later machines with a DSP. None had a 2nd general purpose CPU running concurrently. The BBC micro had the brilliant 'Tube' interface, but the co-pro essentially took over the whole system.
Anything the 2nd 6502 could do, a dedicated chip will do it better. It would be more interesting to have say a Z80 along with the 6502, then you could run CP/M. Or perhaps something similar to the 'PiTube' for the BBC? ?
Just wanna add: didn't BBC Micro support a second 6502 processor though? (as an expansion option)
EDIT: Oops, I accidentally published the same comment twice!
Two 6502 System
Posted: Wed Dec 22, 2021 4:06 pm
by xanthrou
On 7/28/2021 at 10:30 PM, Gromit337 said:
As the OP said, from a technical point of view it's an interesting idea, but practically, it's just a solution looking for a problem to solve.
Back in 1979, Atari 8 bits had Antic, Pokey, CTIA/GTIA etc. But they were custom chips and each served a specific purpose. The same with their spiritual successor, the Amiga. Even Atari equipped later machines with a DSP. None had a 2nd general purpose CPU running concurrently. The BBC micro had the brilliant 'Tube' interface, but the co-pro essentially took over the whole system.
Anything the 2nd 6502 could do, a dedicated chip will do it better. It would be more interesting to have say a Z80 along with the 6502, then you could run CP/M. Or perhaps something similar to the 'PiTube' for the BBC? ?
Just wanna add: didn't BBC Micro support a second 6502 processor though?
Two 6502 System
Posted: Wed Dec 22, 2021 4:58 pm
by Calculon
On 12/22/2021 at 8:06 AM, xanthrou said:
Just wanna add: didn't BBC Micro support a second 6502 processor though?
Pretty much any second processor you wanted, if it was on a board designed to comply with the Tube interface.
Two 6502 System
Posted: Wed Dec 22, 2021 5:21 pm
by Edmond D
On 12/22/2021 at 8:06 AM, xanthrou said:
EDIT: Oops, I accidentally published the same comment twice!
Goes with the two processor theme
?
Two 6502 System
Posted: Wed Dec 22, 2021 8:24 pm
by martinot
On 12/22/2021 at 5:06 PM, xanthrou said:
Just wanna add: didn't BBC Micro support a second 6502 processor though?
It was for support of other CPUs in general.
Trivia: This was actually how the first ARM processors was tested and developed for.