1. GCSE Computing
Memory
Powerpoint Templates

2. Objectives Describe the difference between RAM and ROM
Explain the need for ROM in a computer system
Describe the purpose of RAM in a computer system
Explain how the amount of RAM in a personal computer affects the performance of the computer
Explain the need for virtual memory
Describe cache memory
Describe flash memory
Discuss how changes in memory technologies are leading to innovative computer designs.

3. Describe the difference between RAM and ROM
A computer uses two types of storage. A main store consisting of ROM and RAM, and backing stores which can be internal, e.g. hard disk, or external, e.g. a CD or USB flash drive.
RAM is a fast temporary type of memory in which programs, applications and data are stored. Here are some examples of what's stored in RAM:
the operating system
applications
the graphical user interface (GUI)
If a computer loses power, all data stored in its RAM is lost. RAM is therefore considered ‘Volatile’.

4. Describe the difference between RAM and ROM
ROM is memory that cannot be changed by a program or user. ROM retains its memory even after the computer is turned off.
For example, ROM stores the instructions for the computer to start up when it is turned on again.
It forms the basic instruction set for operating the hardware in the system, and the data within remains intact even when the computer is shut down.
ROM is considered ‘Non-Volatile’.

5. Explain the need for ROM in a computer system
ROM should be thought of as storage which is written and then cannot be changed. Once written the only way to destroy the data is to destroy the device holding the data.
If ROM is damaged, the computer system simply cannot function.

6. Describe the purpose of RAM in a computer system
RAM only holds data while power is present.
RAM changes constantly as the system operates, providing the storage for all data required by the operating system and software.
Because of the demands made by increasingly powerful operating systems and software, system RAM requirements have accelerated dramatically over time.
For instance, at the turn of the millennium a typical computer may have only 128Mb of RAM in total, but in 2010 computers commonly ship with 8Gb of RAM installed.

7. Explain how the amount of RAM in a personal computer affects the performance of the computer
Computers depend on RAM to run processes and applications; the sophistication and number of processes and applications running create a greater need for RAM.
When a computer with too little RAM is attempting to run several processes, each one may not have access to as much RAM as it requires to run optimally, so they will slow down, taking noticeably more loading time to complete any commands.
On a slow-running computer, running fewer processes and programs will often allow the available RAM to be devoted to the task a user is actually concerned with, speeding up the computing experience.
Users can either add more RAM or add faster RAM to improve performance.

8. Explain the need for virtual memory
Virtual memory frees up space in your computer's RAM.
Unfortunately, most computers today will not have enough RAM to run all of the programs that most users expect to run at once.
For example, if you load the operating system, an program, a Web browser and word processor into RAM simultaneously, 32 megabytes is not enough to hold it all. If there were no such thing as virtual memory, then once you filled up the available RAM your computer would have to say, "Sorry, you can not load any more applications. Please close another application to load a new one."
With virtual memory, what the computer can do is look at RAM for areas that have not been used recently and copy them onto the hard disk. This frees up space in RAM to load the new application.

9. Describe cache memory
A small amount (normally less than 1MB) of high-speed memory residing on or close to the CPU. Cache memory supplies the processor with the most frequently requested data and instructions. Level 1 cache (primary cache) is the cache closest to the processor. Level 2 cache (secondary cache) is the cache second closest to the processor and is usually on the motherboard.

10. Describe flash memory
Flash memory is a non-volatile computer storage technology that can be electrically erased and reprogrammed. It is primarily used in memory cards, USB flash drives, and solid-state drives for general storage and transfer of data between computers and other digital products.

11. Discuss how changes in memory technologies are leading to innovative computer designs.
Video – Institution Lectures 1 (DVD)