Darkknight512

I am trying to get back into programming and would like to know how I would go about calculating all the clocks from the bclock on a P4 - Core 2 and I would want to know how the DRAM:FSB ratio is calculated.

I have made basic programs and I know how I'm going to build the program I just need the formulas.

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Grandlo

this is less of a programming question more of a hardware question, it's a driver level thing. those are probably stored in registers in the cpu or northbridge and you'd need to know the instructions(amd) or which memory mapped register or port to read/write to for intel system. i was interested in writing some stuff like this a while back but didn't have the time to do the proper research. if you find any good documentation/faq's please keep me posted.

it'd be much easier to write this software for amd system jsut becasue the cpu handles things so it's accessable via instructions.

Grandlo

man I completely misunderstood your question. I thought you were wanting to make a program like clockgen or systool lol! the FSB:RAM ratio isn't calculated at all, it's just a given. you have the FSB clock and the FSB:RAM ratio and the CPU Multiplier with those three values you can calculate the CPU clock and the RAM clock.

I tend to use the terms base clock and FSB interchangibly for simplicity I'll just not do that from here out..

FSB = BC(base clock)*4

CPU_FREQ = BC * CPU_MULT

RAM_CLOCK = BC * RAM / FSB
---> where RAM and FSB are the numbers from ration FSB:RAM ratio

but also remember that ram is DDR(double data rate) thus the effective frequency is

RAM_EFF_FREQ = RAM_CLOCK * 2