Types of Memory
Computer Science: OCR GCSE, topic 1.2.1
Random Access Memory
Random Access Memory (RAM) is one of the two types of main memory found in computers. General purpose computers usually contain a large amount of RAM. The features of RAM are:
Volatile
- RAM is volatile. This means that it will lose its contents when power is lost (i.e. if the computer is switched off).
Fast
- RAM is much faster to access than secondary storage such as Hard Disk Drives (HDDs).
Expensive
- RAM is much more expensive per unit capacity than secondary storage media.
Random access
- Random Access means that any part of the memory can be accessed non-sequentially and as quickly as any other part of the memory.
Read Only Memory
Read Only Memory (ROM) is another type of main memory found in computers. It comes on a small, factory made chip in the motherboard. Features of ROM include:
Non-volatile
- ROM is a type of primary storage.
- ROM is non-volatile.
- This means that ROM keeps its contents when power is lost.
- Primary storage is important as it allows memory retention even when power is lost.
Read only
- ROM is often made from flash memory. This means that its contents cannot be changed easily.
- This means that the ROM only stores small programs that boots or starts up the computer.
- These programs are called the Basic Input Output System (BIOS). They usually:
- Load an operating system.
- Check the system for errors.
Fast but expensive
- ROM is very fast to access.
- ROM is typically expensive, so tends to be only small.
Test yourself on Types of Memory
What's Random Access Memory an example of?
Which of these tends to be faster to access?
Which of these tends to be cheaper per unit capacity?
What are the properties of ROM?
Which does a general-purpose computer usually have more of?