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Hardware Basics:Inside The Box

Chapter 2

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Topics

What Computers Do

 Bits, Bytes, and Buzzwords

The Computer’s Core

The Computer’s Memory

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Thomas J. Watson, Sr.

The “emperor” of IBM

Created a culture of invention

IBM remains an industry leader and innovator

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What Computers Do

Receive

Input

Process Information

Produce

Output

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What Computers Do

Store Information

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Input Devices

The keyboard is the most common input device

Pointing devices like the mouse also receive input

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Output Devices

Computers produce information and send it to the outside world.

A video monitor is a common output device.

Printers also produce output.

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Process Information

The processor, or central processing unit (CPU), processes information and performs all the necessary arithmetic calculations.

The CPU is like the “brain” of the computer.

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Store Information

Memory and storage devicesare used to store information

Primary storage is the computer’s main memory

Secondary storage uses disks or other media

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Information

Information comes in many forms

Computers store information in digital form

Text

12 3Numbers SoundsPictures

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Bit Basics

A bit (binary digit) is the smallest unit of information can have two values: 1 or 0 can represent numbers, codes, or

instructionsOn

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Bits as Numbers

Each switch can be used to store a tiny amount of information, such as: An answer to a yes/no question A signal to turn on a light

Larger chunks of information are stored by grouping bits as units 8 bits (byte) = 256 different messages

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Bits As Codes

ASCII – American Standard Code for Information Interchange

Most widely used code, represents each character as a unique 8-bit code.

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Bits as Instruction

The computer stores instructions as collections of bits. For instance, 01101010 might instruct the computer to add two numbers.

Other bit instructions might include where to find numbers stored in memory or where to store them.

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Bits, Bytes, and Buzzwords

Byte Kilobyte (KB) Megabytes (MB) Gigabytes (GB) Terabytes (TB)

= 8 bits

= 1 Thousand Bytes

= 1 Million Bytes

= 1 Billion Bytes

= 1 Trillion Bytes

Terms used to describe file size or memory size:

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The CPU and Memory

The microprocessor that makes up your personal computer’s central processing unit, or

CPU, is the ultimate computer brain, messenger, ringmaster and boss. All the other components—RAM, disk drives, the

monitor— exist only to bridge the gap between you and the processor.

Ron White, in How Computers Work

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The CPU

The CPU:

interprets and executes instructions

performs arithmetic and logical data manipulations

communicates with the other parts of the computer system.

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The CPU

The CPU is a complex collection of electronic circuits.

When all of those circuits are built into a single silicon chip, the chip is referred to as a microprocessor.

The circuit board that contains a computer’s CPU is called the motherboard or system board.

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Compatibility & Speed

When purchasing a computer, selecting a CPU is very important. The two most critical factors are:

Compatibility Speed

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Compatibility

Software is written for a specific processor and may not be compatible with another CPU.

Every processor has a built-in instruction set or vocabulary of instructions that only the processor can execute.

CPUs in the same family are generally designed to be backward compatible so newer processors can process all of the instructions handled by earlier models.

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Speed

A computer’s speed is determined in part by the speed of its internal clock

The clock is a timing device that produces electrical pulses to synchronize the computer’s operations.

A computer’s clock speed is measured in units called megahertz (MHz), for millions of clock cycles per second

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Speed

Clock speed by itself doesn’t adequately describe how fast a computer can process words, numbers, or pictures.

Speed is also limited by architecture and word size.

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Speed

Parallel processing places multiple processors in a computer.

Most supercomputers have multiple processors that divide jobs into pieces and work in parallel on the pieces.

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The Computer’s Memory

RAM (random access memory):

is used to store program instructions and data temporarily

unique addresses and data can be stored in any location

can quickly retrieve information

will not remain if power goes off (volatile)

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The Computer’s Memory

ROM (read-only memory):

information is stored permanently on a chip. contains startup instructions and other permanent data.

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Buses connect to storage devices in open areas in the box called bays.

Buses, Ports, and Peripherals

Information travels between components through groups of wires called buses.

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Busses also connect to slots inside the computer

Sockets on the outside of the computer called ports.

Buses, Ports, and Peripherals

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Buses, Ports, and Peripherals

Slots and ports also allow external devices called peripherals to be added to the system (keyboard, monitor, and mouse).

Without peripherals, the CPU and memory are like a brain without a body.

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