- 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.
