# [coreboot] Memory clock cycles -> microseconds (us)

Joseph Smith joe at settoplinux.org
Mon Jun 9 19:36:29 CEST 2008

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On Mon, 9 Jun 2008 19:14:32 +0200, Peter Stuge <peter at stuge.se> wrote:
> On Mon, Jun 09, 2008 at 01:06:08PM -0400, Joseph Smith wrote:
>> >> Does anyone know the mathematical formula for converting memory
>> >> clock cycles into microseconds (us)??
>> >
>> > 1 MHz means 1 million clock cycles per second, so 1 clock cycle
>> > per microsecond.
>> >
>> > 166 MHz -> 166 clock cycles per microsecond.
>>
>> Thanks Myles:-)
>> I didn't realize it was that easy.
>> So, for example if a memory initialization datasheet says you
>> should delay for 3 clocks than that means 3us, correct?
>
> Only if the memory clock is 1MHz, but if it's 166MHz then delay for
> 3/166 microseconds = 18 nanoseconds
>
>
> The formula is: t=1/f
>
> If f=1000000, each cycle is 1/1000000 seconds, or 1 microsecond.
> If f=166000000, each cycle is 1/166000000 seconds, or 1/166 us = 6 ns
>
>
Ok, let me get this straight. So in my case the memory is PC133 which is
133 MHz. So each clock cycle is 1/133 us? And, to delay for 3 clocks would
be 3/133 us = 22 ns?

--
Thanks,
Joseph Smith
Set-Top-Linux
www.settoplinux.org

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