Factors Affecting Processing Speed

• Registers
• RAM
• The System Clock, 
• The Bus
• Cache Memory

Registers: 

• The CPU contains of small memory areas:called registers,which store data and instructions while the CPU processes them.
• The size of the registers determines the amount of data with which the computer can work at a one time.
• Today most PC`s have 32-bit registers,mean the CPU can process four bytes data at one time.Register sizes are rapidly growing to 64 bits.

RAM: 

• The amount of RAM in a PC has a direct affect on the system`s speed.
• The more RAM a PC has.the more program instructions and data can be held in memory,which is faster than storage on disk.
• If a PC does not have enough memory to run a program,it must move data between RAM and the hard disk frequently.This process called swapping,can greatly slow a PC`s performance. 

                                        More RAM=Better Performance!  

The System Clock: 

• The computer`s system clock sets the pace the CPU by using a vibrating quartz crystal.
• A single "tick" of the clock is the time required to turn a transistor off and back on.This is called a clock cycle.
• Clock cycles are measured in Hertz(Hz),a measure of cycles per second.If a computer has a clock speed of 300 MHz, then its system clock"ticks" 300 million times every seconds.
• The faster a PCs clock runs,the more instructions the PC can execute each second. 

The Bus: 

• A bus is a path between the components of a computer.Data and instructions travel along these paths.
• The data bus width determines how many bits can be transmitted between the CPU and other devices.
• The address buss runs only between the CPU and RAM, and carries nothing but memory addresses for the CPU to use.
• Peripheral devices are connected to the CPU by an expansion bus. 

Cache Memory: 

• Cache memory is high-speed memory that holds the most recent data and instructions that have been loaded by the CPU.
• Cache is located directly on the CPU or between the CPU and RAM,making it faster than normal RAM.
• CPU-resident cache is called Level-1 (L1)cache.External cache is called Level-2(L2) cache.
• The amount of cache memory has a tremendous impact on the computer`s speed.

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