Overclocking Blizzard1260

[amigagr]

but what could this in practice mean for an overclocked 060?
i have a crystall at 66 and 2x32mb simms at 50ns but can this be safe and stable? more than this can be safe at higher speeds with these 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).

[amigagr]

these more ''wait states'' finaly result in a less
mips performance/mhz?

[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.

[oldtimeman]

you can run apollos and blizzards to 80 mhz and above i have overclocked apollo 1260 to100 mhz blizzard to 80