Introduction to Computers

Section 4ASection 4A

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Decimal Number System

Called base 10 because 10 symbols are

available

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Binary Number System

Computers function in base 2, or the

binary number system, where there are

only two values

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Bit

A combination of binary digit

The smallest possible unit of data a computer can recognize or use

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Byte

A group of eight bits

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Text Codes

EBCDIC

ASCII

Unicode

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CPU

The CPU is the computer’s “brain” that

manipulates data

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CPU’s Two Basic Parts

Control unit

Arithmetic logic unit

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Control Unit

Manages all the computer’s resources

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Arithmetic Logic Unit

Performs the CPU’s arithmetic and

logical operations

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Machine Cycle

The completed series of steps the CPU

takes to execute an instruction

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Machine Cycle’s Two Cycles

Instruction cycle

Execution cycle

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Instruction Cycle

Fetching

Decoding

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Execution Cycle

Executing

Storing

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Millions of Instructions Per Second (MIPS)

The CPU performance measurement

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Pipelining

Also called pipeline processing

The control unit begins a new machine

cycle before the current cycle is

completed

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Memory

Allows the CPU to store and retrieve

data quickly

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Two Kinds of Memory

Read-only memory (ROM): nonvolatile

Random-access memory (RAM): volatile

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ROM

ROM always holds the same data, for

example the computer’s start-up

instructions

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RAM

RAM’s job is to hold programs and data

while they are in use

RAM can change instantly

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Other Kinds of RAM

Dynamic RAM (DRAM)

DRAM Variations

Static RAM (SRAM)

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Factors Affecting Processing Speed

Registers

Memory and computing power

System clock

The bus

The databus

The address bus

Cache memory

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Bus Types

Industry standard architecture (ISA) bus

Local bus

Peripheral component interconnect (PCI) bus

Accelerated Graphics Port (AGP) bus

Universal Serial Bus (USB)

IEEE 1394 (FireWire)

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Data Transfer Rate

The amount of data buses can transfer in a

second

Measured in megabits per second (Mbps) or

megabytes per second (MBps)

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Cache memory

Speeds processing by storing

frequently used data or instructions in

its high-speed memory

Section 4ASection 4A

Transforming Data Into Transforming Data Into InformationInformation