Computer Systems Nat 4/5 Computing Science Section 2 Computer Structure: Lesson 6: Memory

Lesson Aims By the end of this lesson: Pupils will be able to: Describe of the features and uses of RAM and ROM. Describe what is meant by a memory address

A quick recap We are going to look at Memory Nat 4/5 Processor Input Devices Output Devices Memory Backing Storage We are going to look at Memory

Main Memory There are two types of main memory falls : RAM RAM ROM Nat 4/5 Main Memory Main Memory RAM ROM There are two types of main memory falls : RAM Random Access Memory ROM Read Only Memory

Nat 4/5 Addressability Your house has a unique address, made up of street, town and postcode. No two houses have the same address! This is the same for memory in the computer Memory is made up of thousands of millions of storage locations Each storage location in memory has it’s own unique address so that the processor can locate it This address is a binary value e.g 1110100100101001

RAM – Random Access Memory Nat 4/5 RAM – Random Access Memory Operating system is loaded into RAM when the computer starts up Stores programs and data that a user is currently using Contents of RAM are lost when the computer is switched off… …so the user’s work must be saved to backing storage medium e.g. a hard disk Direct-access medium = data can be read from RAM or written to RAM in any order

N5 Amount of RAM Plenty of RAM improves computer performance because means:- you can have lots of programs in memory at one time you can run larger programs

ROM – Read Only Memory There is a problem with just having RAM. Nat 4/5 ROM – Read Only Memory There is a problem with just having RAM. If the contents of RAM are lost then the power is Iost how does the computer know what to do when it switches on? ROM (Read Only Memory) is memory that will always retain its contents even when power is lost. This concept can be used by mobile phones to store their operating systems.

Flash ROM

Summary RAM (Random Access Memory) ROM (Read Only Memory) Nat 4/5 Summary RAM (Random Access Memory) Is used to store programs and the operating system Is volatile, which means it loses its contents when there is no power ROM (Read Only Memory) Contents cannot be changed and does not require power to hold data

Questions How can the processor identify each location in memory? What type of memory stores the programs that the user is currently using? What type of memory stores essential programs that make the computer work? What type of memory is volatile?