The Computer s Memory, Storage and Processor. Part I Memory (Primary Storage)

The Computer’s Memory, Storage and Processor Part I – Memory (Primary Storage) What is Memory? Memory is the usable Brain Capacity of the computer, ...
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The Computer’s Memory, Storage and Processor Part I – Memory (Primary Storage)

What is Memory? Memory is the usable Brain Capacity of the computer, it is also an area of storage whether temporary or permanent. Memory consists of electronic components that store instructions waiting to be executed by the processor, data needed by those instructions, and the results of processed data (information). The role of memory is to both store data and programs (stored program concept).

There are two types of Memory y

RAM – Random Access Memory (Volatile)

y

ROM – Read Only Memory (Non-Volatile)

Attributes of RAM Data can be both read from and Written to it. y It is only available while the computer is turned on. y Its Portable, your computer can use various types of RAM Chips, making upgrade more convenient. y

Attributes of ROM Data can only be read from it but not written to it, with the exception of EEPROM. y Data is permanent and is available while the computer is off. y

A Closer Look at RAM Technology Cache (pronounced cash) y Dynamic RAM: DRAM, Synchronous DRAM, Double Data Rate SDRAM (DDR SDRAM), DDR2-3 SDRAM and Ram bus DRAM. y Static RAM y Magneto resistive RAM (MRAM) y

A Closer look at ROM Technology PROM (Programmable read only memory) y EPROM (Erasable PROM) y EEPROM (Electrically Erasable PROM) y Flash Memory y CMOS (Complementary metal-oxide semiconductor) y

The Computer’s Memory, Storage and Processor Part II – Secondary(Auxillary) Storage

Secondary Storage Devices store data permanently for easy Read/Write Access

CD / DVD (Optical)

USB Flash Drive

Hard Drive (Magnetic)

Magnetic Tape Device

Floppy Disk (Magnetic)

Zip Disk (Magnetic)

A list of Secondary Storage Devices: Magnetic Disks (Direct Access Device): Hard Disk, Floppy Disk, Zip/Jazz Disk y Magnetic Tape( Sequential Access Device): Tape Reels, Tape Cartridge, Microfilm y Optical Storage (Direct Access Device): CD-ROM, DVD-ROM, WORM Disk, y Bistable Storage (Direct Access Device): USB Flash Drive, Flash Memory Cards y

Direct Access Vs Serial / Sequential Access. Direct Access

Serial / Sequential Access

Can Randomly Access Information at any point on the disk, making access time faster. Direct Access devices are more suitable real-time data access.

Has to access information in the order that it was stored, therefore slower access time. Sequential Access devices are more suitable to backing up data.

Technology Costs more

Technology is Cheaper

More popular in the Home and Office.

More Popular in Large Organizations.

Magnetic Disk Storage Technology

Magnetic Tape Storage Technology

Optical Storage Technology Spiral

The Computer’s Memory, Storage and Processor Part III – The Processor

The processor also called the central processing unit (CPU), interprets and carries out the basic instructions that operate a computer.

Characteristics of a Processor The Control Unit y The Arithmetic Logic Unit y Registers y System Clock y

Purpose of the Control Unit The control unit directs the entire computer system to carry out stored program instructions.

Purpose of the Arithmetic Logic Unit y y

The arithmetic logic unit executes arithmetic and logical operations. Arithmetic operations include addition, subtraction, multiplication and division.

Purpose of the Registers Registers are small high speed storage locations that temporarily hold data and instructions. Registers Store; Fetched instructions while the control unit decodes it and data, while the ALU computes it.

Purpose of the System Clock The System Clock is a small quartz circuit used for controlling timing operations. Each Tick equates a clock cycle (this is measured in Megahertz and Gigahertz). N.b. A hertz is one cycle per second. E.g. 3.8 GHz means 3.8 billion cycles per second.

Dataflow Diagram for the Processor

End of Lecture. Please Submit your questions to [email protected] and also do the relative questions provided.

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