RAM & ROM (AQA GCSE Computer Science)
Revision Note
Written by: Robert Hampton
Reviewed by: James Woodhouse
RAM
What is RAM?
RAM (Random Access Memory) is primary storage that is directly connected to the CPU and holds the data and instructions that are currently in use
RAM is volatile which means the contents of RAM are lost when the power is turned off
For the CPU to access the data and instructions they must be copied from secondary storage
RAM is very fast working memory, much faster than secondary storage
RAM is read/write which means data can be read from and written to
In comparison to ROM, it has a much larger capacity
ROM
What is ROM?
ROM (Read Only Memory) is primary storage that holds the first instructions a computer needs to start up (Bootstrap)
ROM contains the BIOS (Basic Input Output System)
ROM is a small memory chip located on the computers motherboard
ROM is fast memory, much faster than secondary storage but slower than RAM
ROM is non-volatile which means the contents of ROM are not lost when the power is turned off
ROM is read only which means data can only be read from
In comparison to RAM, it has a much smaller capacity
Differences between RAM & ROM
Feature | RAM | ROM |
|---|---|---|
Speed | Very fast | Fast (slower than RAM) |
Capacity | Gigabytes (GB) | Megabytes (MB) |
Stores | Programs and data in use | Bootstrap (start-up instructions) |
Read/Write | Read & write | Read only |
Volatile/Non-volatile | Volatile | Non-volatile |
Worked Example
State two reasons why computers have more RAM than cache memory [2]
Answer
RAM is cheaper (per byte than Cache)
The capacity of cache will usually be big enough to store currently open programs and data
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