Sat 24 October 2020

Power Supply: System Unit

The power supply of a computer is a simple electrical system. It is used to supply the correct voltage to different components of the computer. It takes 240 or 110 AC voltages as input. It converts AC voltage into 3v, 6V, 12V, and 24V of direct current (DC).

Different devices work with different voltages. Power supply detects the amount of voltage that a device requires. It supplies the correct amount of voltage to different devices.



Bay is an open area inside the system unit to install additional equipment. Bays are also called drive bays. Two types of bays are as follows:

  • External or Exposed Drive Bay: It is used to access the drive from outside the system unit. Some examples of external drive bays are floppy disk drive, CD drive, DVD drive, and Zip drive.
  • Internal or Hidden Drive Bay: It is hidden inside the system unit. An example of an internal drive bay is a hard disk drive.


Factors Affecting Processing Speed

The following are some important factors that affect the processing speed of a computer.

  • Registers
  • RAM
  • System Clock
  • Buses
  • Cache Memory


1. Registers

The register is a small, high-speed memory inside a CPU. CPU contains a number of registers. Registers 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 one time. It is also called word size.

The size of registers is in bytes. A register can be of one, two, four, or eight bytes. Computers with 32-bit registers mean the CPU can process four bytes of data at one time. The bigger size of the register increases the performance of the computer.


2. RAM

The Amount of RAM directly affects the processing speed of the computer. A bigger amount of RAM means that more program instructions and data can be stored in memory. If a computer does not have enough memory to run a program, it must move data between RAM and the hard disk frequently. This process is called swapping that can greatly slow a computer's performance.


3. System Clock

The system clock is an electronic component. It generates electric signals at a fast speed. The time required to execute a single instruction is called clock speed. Clock speed tells us how much time a CPU takes to execute each instruction CPU takes from 1 to 6 clock ticks to execute one instruction.

 Clock speed is measured as cycles per second. Its unit is Hertz (Hz). If a computer has a clock speed of 300 MHz, its system clock ticks 300 million times every second. A faster clock can execute more instructions each second.


4. Buses

A bus is a path between the components of a computer. Data and instructions travel along these paths. The bus width determines how many bits can be transmitted between the CPU and other devices. Bus width also affects the performance of the computer. A higher bus width means that the user can carry more data. It increases the performance of the computer.


5. Cache Memory.

A cache (pronounced "cash") is high-speed memory that holds the most recent data and instructions that have been loaded by the CPU It is designed to speed up the transfer of data and instructions Cache is located directly on the CPU or between the CPU and RAM it is faster than RAM.

The data and instructions are retrieved from RAM when the CPU uses them for the first time. A copy of that data or instructions is stored in the cache. The next time the CPU needs that data or instructions, it first looks in the cache. If the required data is found there, it is retrieved from cache memory instead of the main memory. It speeds up the working of CPU. The amount of cache memory has a tremendous impact on the computer's speed.