MEGA65 FORUM

WHAT MICROPROCESSOR ?

append delete Dan Laskowski

What is under the hood? Another Intel or AMD chip running VICE ?

Dan

Will this fully support the Expansion port and Cartridge slot? My MIDI interface uses these.

Thanks

Dan

http://musicinit.com/fastfingers.php

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append delete #1. gardners

The MEGA65 uses an FPGA implementing an enhanced 6502 processor, the 45GS02, that supports all the instructions of the C65's 4510, as well as being able to switch to 6502 mode, where we intend to have full illegal opcode support. The CPU currently supports 1MHz, 2MHz, 3.5MHz and 40MHz modes (the final top speed may vary around that 40MHz point. It was 48, then 50, now currently 40. The final decision will be made soon before release, when we have timing closure and exact FPGA part selection nailed down).

There is no "modern" processor. Just pure 8-bit. i.e., the MEGA65 is very different to the C64 Mini, for example.

Paul.

append delete #2. Dan Laskowski

Very interesting. THANK YOU.

append delete #3. pad00100

Outstanding ! C64 running on 40MHZ! We can imagine what DemoScene Masters will do with that power ! :D ..I have one question about CPU speed.. What is possible maximum CPU speed which we could have on FPGA implementation ? I know that 40MHZ is enough.. but ..If we could have 100MHZ or more.. that will be more and more great ;)

append delete #4. gardners

It is really all a question of work. I believe 100MHz - 150MHz would be possible. Moreover, that would be with a pipelined (but not speculative) CPU that would be able to dispatch one instruction almost every cycle, compared with every ~3 - 4 cycles in a standard 6502. Thus it would be something like 3x clock speed and 3x instruction throughput, so would be getting close to 10x faster than the current CPU.

But that will definitely not be happening before the MEGA65 is released for sale.

Paul.

append delete #5. Gunstarrhero

would you consider using an arm processor as a co processor? say we get into some heavy game development (quake) we are going to need an fpu and a strong run on the processor to run the game efficiently. (i know thats a laugh and silly, still... think BIG)
an arm processor running as an fpu or implementing a strong fpu to the fpga would be a very bright way to go. oh yeah dont forget to build specific handlers for geos in c65 state so we can just run it direct from the prompt :) what also would be nice is the ability to install geos to a "hard disk chip" and boot from the chip. i know you dont want this stuff, i know you are prolly saying "why" ? its exactly what the c64 needed and commodore decided against. we coulda had geos at boot.

if we woulda had geos at boot, commodore would have been even further in direct competition with Apple.

append delete #6. Gunstarrhero

make the clock as fast as possible. 50mhz/100mhz :)

append delete #7. gardners

We want it to only be 8-bit processors, so no ARMs. It would have been so much easier if we allowed a big processor, but for us, that spoils the result.

Paul.

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