Computer systems

Computer systems

1. Central Processing unit (CPU)

   • The CPU is an integrated circuit often referred to as the 'brain' of a computer system.
   • It can make calculations based on sets of instructions and moves data between memory locations.
   • It carried out the fetch execute cycle which finds sets of instructions within the system, decodes what they mean and then carries the instructions out.
   • CPU clock speed is an important specification of any processor because it determines how quickly instructions can be executed. It is measured in cycles per second, known as Hertz (Hz).

2. Motherboard

   • the mother board allows system components to connect and communicate with each other via a central unit.

3. Read Only Memory (ROM)

   • Read-Only Memory can only be read and not written to. It’s permanent, so data stored is retained when the computer is powered down.
   • ROM is located on the motherboard and is used to store the BIOS, which runs each time the computer is started. While it in not volatile (can store data without power) it is slow to retrieve data.

4. Random Access Memory (RAM)

   • Random Access Memory can be both read and written to by the CPU
   • Is temporary so any data stored in RAM is lost when the computer is powered down. It is used to hold data that is currently in use such as the text on a word document. This memory is volatile but is faster to retrieve that data than ROM.

5. Cache memory

   • Located in the CPU
   • High-speed memory used as a temporary store for recently processed instructions and data or for those which the CPU anticipates will be required soon
   • A large cache is desirable but cache memory is expensive.

6. Fan

   • Fans are used to draw cooler air into the case from the outside, expel warm air from inside and move air across a heat sink to cool a particular component.

7. Hard Disk Drive

   • data storage device for storing and retrieving large volumes of data, using one or more rapidly rotating disks (platters) coated with magnetic material
   • The platters are paired with magnetic heads, which read and write data to the disk surfaces. HDDs retain information even when powered off because the data is stored magnetically.

8. Solid State Drive

   • Uses flash memory instead if magnetic platters, this acts like RAM when the device has power yet behaves like ROM when the device is powered down
   • This typically works faster than magnetic storage devices.

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