What is a clock cycle?

[Saint71]

Could somone explain in laymans terms what it is.

 

[aliasaid]

its where the big hand goes all the way around

 

[Saint71]

I am refering to a clock cycle used by a microprocessor.

 

[mophead740]

google is ure friend

 

[mophead740]

the clock cycle is the number of thingsa processor can do per second
the things are known as pulses
this is measured in MHz (megahertz) which is a million pulses per second or GHz (gigahertz) a billion pulses per second

 

[mophead740]

by the way
try to fix ur sig sometime soon

 

[Meithan]

A microprocessor functions by executing simple operations that are in a list (a program). Such operations include reading and writing to memory (the RAM in your computer), performing arithmetic operations (sums, multiplications, etc), and getting and generating Input/Output signals (such as writing to disk, or displaying things on-screen). So that these instructions are carried out in order, there is a thing called a clock signal that tells the CPU when to execute each instruction. Imagine it's a device "feeding" the processor these instructions one by one.

A clock cycle is the basic unit of time in which the processor carries out a defined numbers of these actions. In one clock cycle, the CPU could for instance READ from memory, perform an operation on the data and then WRITE to memoy. The clock signal is kind of the orchestra director, it tells the CPU when to do things.

Why is this important? Because the shorter a clock cycle is, the faster the CPU will do things. The clock frequency of a CPU tells us how many cycles there are in a second of time. A 1Ghz processor goes through 1 billion clock cycles per second! The larger the frequency, the more instructions the CPU can do per second.

I hope that explained the issue a bit.

 

[Saint71]

That makes sense. But here is another question. Say I have a 64 bit processor that is running at 2ghz. Now does that mean the cpu can process 64bits of information 2 billion times a second? Because it can calculate 64 bits of information per clock cycle.

 

[Meithan]

That's a good guess but it's not quite correct. When the processor is running, it stores information (both data and instructions) in internal storage places called "registers". What the 64-bit means is that these registers hold numbers that are 64 bits in length. Remember binary? It's the way a computer represents numbers. As an example, a binary number that measures 8 bits can go from 0 to 255. So an 8-bit processor has registers that can only "understand" numbers from 0 to 255.. quite limited, don't you think?

Now, a 64-bit binary number goes from 0 to 18,446,744,073,709,551,616!! It means it can recognize a virtually infinite amount of numbers. This represents a huge increase over 32-bit computing, specially in the amount of RAM the processor can address.

So the short answer to your question is nope, it doesn't mean the processor can "calculate" 64 bits of information, it's just a statement of the format the processor uses to store internal information.

If you wanna know more, check the following site:
http://arstechnica.com/cpu/03q1/x86-64/x86-64-1.html