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Computer Systems

Computer Systems. Nat 4/5 Computing Science Section 2 Computer Structure: Lesson 2 : Memory. Nat 4/5. Lesson Aims. By the end of this lesson: Pupils will be able to: Identify the parts of main memory Describe of the features and uses of RAM and ROM Describe backing storage

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Computer Systems

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

  2. Nat 4/5 Lesson Aims By the end of this lesson: • Pupils will be able to: • Identify the parts of main memory • Describe of the features and uses of RAM and ROM • Describe backing storage • Describe what is meant by addressability

  3. Revision Nat 4/5 Bus Processor Main Memory Bus Label the diagram of the processor, buses and main memory

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

  5. Nat 4/5 Main Memory Main Memory • Main memory falls into two types: • RAM • Random Access Memory • ROM • Read Only Memory RAM ROM

  6. Nat 4/5 RAM – Random Access Memory • Nothing to do with male sheep! • RAM is the computers short term memory. • If a machine is quoted as having 2GB of Ram then it has 2GB into which programs and the operating system is loaded into. • RAM is volatile. • This means that it requires power to store data. • When power is lost the contents of RAM are lost.

  7. 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.

  8. Nat 4/5 Addressability • Your house has a unique address • No two houses have the same address! • This is the same for a computers memory • Each location in memory has it’s own unique address (memory address). • This means each piece of data (1000101) will be stored in it’s own memory location which will have it’s own address • The processor can retrieve any bit of data that is needed. This is known as addressability.

  9. Nat 4/5 Backing Storage • Backing storage are devices used to store permanent copies of our files. • Examples are such as: • Hard Disk Drives • USB Flash Drives • Magnetic Tapes • CD/DVD R/RW • At this point in the course knowing their purpose is sufficient. More on these later!

  10. Summary RAM (Random Access Memory) Is used to store programs and the operating system Is volatile, it loses contents when there is no power ROM (Read Only Memory) Contents cannot be changed and does not require power to hold data Addressability The ability to retrieve data from a memory location using it’s address Backing Storage devices are used to store permanent copies of our files and data Nat 4/5

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