100 MHz 6502
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Scott Robison
- Posts: 952
- Joined: Fri Mar 19, 2021 9:06 pm
100 MHz 6502
On 10/13/2021 at 1:44 PM, John Federico said:
When I first read that, my thought was "I've heard about fast 6502 cores realized in an FPGA before." Fortunately, I went on the read the article. That is not what I was expecting. Awesome!
100 MHz 6502
That's amazing. I'm amazed at what people keep coming up with in the 8-bit space.
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Lorin Millsap
- Posts: 193
- Joined: Wed Apr 29, 2020 6:46 pm
100 MHz 6502
This would probably partially work on the X16 with the tricky area being the banked RAM and the zero page mapped Banking registers. If it can be set to externally access $0000 and $0001 as external IO in addition to the main IO range, plus the entire banked range then it would work, but that’s three exception areas.
100 MHz 6502
On 10/19/2021 at 1:36 PM, Lorin Millsap said:
This would probably partially work on the X16 with the tricky area being the banked RAM and the zero page mapped Banking registers. If it can be set to externally access $0000 and $0001 as external IO in addition to the main IO range, plus the entire banked range then it would work, but that’s three exception areas.
Actually, I can see a use case for keeping the RAM available in the upper part of the 65F02's RAM cache.
On the Commodore 64, we can actually write to the RAM that is covered by ROM in the default bank configuration, then turn off the ROM in order to use the RAM underneath. This is how you'd load a custom operating system or a game that uses the top 16K for its own purposes.
I could see doing the same thing here with the 65F02. By selectively enabling the 65F02's cache above $A000, you could use it for a custom operating system, hosted fully inside the 65F02's memory.
This actually sounds like a fantastic upgrade part for the Commander, if it's possible to work with the 65F02's maker to coordinate a reserved address for bank control.
100 MHz 6502
This is featured on this weeks 'This Week in Retro'.
100 MHz 6502
Dumb question: Does this 6502 implementation support the original illegal opcodes, or does it include the extra instructions and addressing modes from the 65C02 and 65CE02? Or neither?
100 MHz 6502
On 10/25/2021 at 6:33 PM, Kalvan said:
Dumb question: Does this 6502 implementation support the original illegal opcodes, or does it include the extra instructions and addressing modes from the 65C02 and 65CE02? Or neither?
As to the illegal opcodes, no it does not (http://www.e-basteln.de/computing/65f02/65f02/ under "Supported Host Systems"):
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The 65F02 supports an optional hardware switch to disable the acceleration. This way, one can still select between accelerated operation and original speed before one starts the host computer. In non-accelerated mode, the 65F02 should be fully compatible with any software or add-on hardware. (Well; unless the software uses undocumented 6502 opcodes…)