index > 2.1.2 computer hardware


There are 2 types of memory: RAM and ROM.

RAM (Random Access Memory) ROM (Read only memory)
Volatile: meaning data is lost when it is turned off Non-volatile: data is retained when it is turned off
Contains the operating system Small (1 or 2MB to boot the computer)
Large (4GB or more)

Virtual Memory

Part of the hard drive and used when the computer doesn’t have enough RAM to hold all the data and programs being used at that time.

It stores the least used programs and data in the virtual memory which can still be accessed, but is slower.

Adding more RAM reduces the use of virtual memory and makes the performance of the computer better.

Cache Memory

Cache memory is the lowest level of memory, meaning it is closest to the CPU. The bigger the processor’s cache, the faster it is as more information can be stored there. It is used to store frequently accessed data, for faster access speeds. If the required data is not in the cache memory the CPU will search the system memory and add it to the cache memory and then process it.

Flash Memory

Flash memory is non-volatile, solid state memory. This means it retains its data when turned off and has no moving parts and is very fast.

The speed is limited by the serial bus speed of the computer which means that internal memory is usually faster. If flash memory is used internally, it becomes faster than mechanical hard drives. It also has a more limited read/write cycle which means it can only be used less. It is more expensive per gigabyte than other types of storage like hard drives and optical disks.

Flash memory like USB memory sticks and SD cards are also very portables, durable and reliable.

How changes in memory technologies are leading to innovative computer designs