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Computer Systems

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 the difference between main memory and backing storage. Describe of the features and uses of RAM and ROM .

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Computer Systems

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

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

  3. 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

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

  5. 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.

  6. 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.

  7. 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

  8. 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!

  9. 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 Backing Storage devices are used to store permanent copies of our files and data Nat 4/5

  10. 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?

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