Amiga bus frequency max?

[psxphill]

That's true, but big box Amiga CPU's have a 25MHz (16Mhz on some 3k's) connection to the motherboard, so that's one limit.

A2000 don't, but yeah A3000 and A4000 have a 50mhz clock on the motherboard. I'd assumed it was used for something else, but it could limit access to 25mhz. There is a clock source jumper, but I don't know what it's for.

[Heiroglyph]

A2000 don't, but yeah A3000 and A4000 have a 50mhz clock on the motherboard. I'd assumed it was used for something else, but it could limit access to 25mhz. There is a clock source jumper, but I don't know what it's for.

Sorry, I always forget 2000's as a "big box" since they are essentially glorified A500's.

I'm 99% sure it's a 25MHz on the motherboard.  Lots of 040s have a 50MHz because that CPU double clocks, but I'm not aware of one on any motherboards.

The clock jumpers determine whether the it uses the clocks from the motherboard or the ones on the CPU card.

[psxphill]

The clock jumpers determine whether the it uses the clocks from the motherboard or the ones on the CPU card.

Yeah, so with a 33mhz CPU card is there still a 25mhz limit?
 
The crystal on the motherboard is either a 32mhz for a 16mhz 68030 or 50mhz for a 25mhz 68030.

[SpeedGeek]

The 28 MHz clock is divided in to 7 MHz for OCS/ECS and 14/7 MHz for AGA. There is nothing actually on the chip bus running from a 28 MHz clock. The chip bus can be overclocked to some extent but it will mess up the Video signal timing.

The 7 MHz Zorro2 and 25 MHz Zorro3 buses could also be overclocked to some extent, but some Zorro2 cards will fail and Zorro3 cards won't realize much performance improvement since they operate from their own (asynchronous) clocks.