Overclocking Blizzard1260

[alexh]

The reason that the Falcon accelerator (Centurbo 6x) can operate at upto 100MHz is 2 fold.

1) They use a much later version of the MC68060RC50 (E41J) which runs MUCH cooler than the earlier ones

2) The Centurbo has 133MHz SDRAM interface.

Running much beyond the 66MHz range is not possible with an amiga accelerator due to the fact they use SIMMs

[alexh]

@AmiBoy

The 75MHz version of the Apollo is probably designed to use more cycles when accessing RAM.

Classically the memory controller on a 50MHz 060 board appears to use 4(?) cycles on RAM access. The 75MHz "firmware" I speculate uses more. I could be wrong however (13ns * 4 = 52ns which may be within the capabilities of SIMMS).

[alexh]

To be honest I dont quite have the knowledge of the relationship between 680x0 CPU cycles (i.e. 50MHz 20ns) and 680x0 Bus cycles, especially when you start to include RAM pre-charge & burst access not to mention synchronous and asynchronous access.

If you look at some of the performance figures of 50Mbyte/s that most 50MHz Amiga 060 cards had it equates to 4 cycles per access. (4 cycles = 80ns)

If you look at the performance figures for the Centurbo they also average 4 cycles per access. However 4 cycles at 100MHz is 40ns, beyond the capability of SIMMS.