Input, Output and Storage Devices

Computer System

• Is a complete working computer.
• Requires an Operating System, Software, and Hardware.

Chapter Overview

• The computer system consists of system concepts, number systems, representation, information coding schemes, as well as logic gates and lastly simple logic circuits.

System Concept Learning Outcomes

• This topic will allow students to explain the four operations involved in the information processing cycle.
  • Input
  • Process
  • Output
  • Storage

What Is a Computer?

• Accepts input in the form of data.
• Processes the data it has received.
• Produces an output, or information, after processing it.

Components of a Computer System

Hardware

• Input Devices
• Output Devices
• Central Processing Unit
• Device Storage

Software

• System Software
• Application Software

Central Processing Unit (CPU)

• Commonly referred to as the "brain" of the computer.
• The CPU is a hardware component that processes and controls the flow of information.
• Interprets and executes the basic instructions needed to operate a computer.
• Consists of two components.
  • Control Unit
  • Arithmetic Logic Unit (ALU)

Input Device

• Any hardware component used to enter data and instructions into a computer.
• Input Device example:
  • Keyboards
  • Built-in laptop keyboard
  • On-screen keyboards
  • Pointing devices (Mouse, Touchpad)
  • Scanners
  • Barcode reader
  • Touch screens
  • Pen input (graphics tablet, Stylus)
  • Voice and audio input (microphone, voice recognition)
  • Video input (digital video camera, webcam)
  • Biometric input (fingerprint reader, iris recognition system)

Output Device

• Any hardware component that conveys information to people.
• Output Device Example:
  • Display devices (Monitors, Projectors)
  • Printers (Inkjet printers, Impact printers)
  • Audio output devices (Headphones, Speakers)

Storage Device

• Hardware that records and/or retrieves items to and from a storage medium.
• Storage Device examples:
  • Hard drives (HDD, SSD)
  • Cloud storage (Dropbox, Google Drive)
  • Portable flash memory storage (Memory card, Thumb drive)
  • Optical Disks (CD, DVD)

Information Processing Cycle

• Represents a sequence of operations that work together repeatedly in a cycle, consisting of 4 stages.
  • Input is the process of entering data into the computer.
  • Process transforms data into information.
  • Output sends/shows information in a usable format.
  • Storage saves data, programs, or information for future use.

Process of Withdrawing Money from ATM

• Input devices are a card reader and keypad.
  • Reads account information.
  • Accepts the type of transaction, personal Identification number (PIN) and amount from user.
• The processor verifies ATM card, PIN, transaction type and amount.
• The processor calculates balance and determines the notes required.
• Outputs cash, a paper transaction receipt, and display messages.
  • Output devices include cash dispenser, printer, and screen monitor.
• Records the transaction and updates the balance on the hard drive.

Windows Calculator Example

• The four main steps in the information processing cycle are:
  • Input of 8 and 2 using the keyboard is entered into the memory.
  • Process multiplies 8 by 2.
  • Output is the result of the process, 16, and is displayed on the screen.
  • Storage is used to keep the data and result multiplication, 8 by 2 = 16, in the memory for future use.

Touch n Go Transaction

• Involves the Information Processing Cycle.
• Input by tapping Touch n Go card to the card reader.
  • The machine reads data, balance, and exit toll gate.
• The Card and calculates the amount to be paid and deducted.
• Output displays the balance and opens the toll gate.
  • A beep sounds and an error is displayed if there are insufficient funds.
• System stores balance, date/time, exit toll gate location, and the transaction history.

Data Representation

• Is the presentation of data in a manner that it can be processed by a computer
• Computer can not process all forms of data.
• It represents the off (0) and on (1).
• Two ways to represent data:
  • Binary Digit (Bit)
  • Byte

Bit (Binary Digit)

• The smallest unit of data a computer can process.
• Represents an electrical state (on or off).
• Bit 1 represents On.
• Bit 0 represents Off.

Byte

• Eight (8) bits grouped together as a unit.
• Represents a character, digit, letter, punctuation mark, or a computer symbol.
• 1 byte = 8 bits.

Difference Between Bit and Byte

• Bit is the smallest unit of data a computer can process.
• A Byte consists of of eight bits grouped together as a unit.

Number System

• Is a collection of symbols or digits used to represent numeric data.
• A set of values used to represent quantity.
• The common number systems are:
  • Decimal (Number Base 10)
  • Binary (Number Base 2)
  • Hexadecimal (Number Base 16).

Base Number Symbols

• Binary - Base 2 - Symbols used 0,1
• Octal - Base 8 - Symbols used 0,1,2,3,4,5,6,7
• Decimal - Base 10 - Symbols used 0,1,2,3,4,5,6,7,8,9
• Hexadecimal - Base 16 - Symbols used 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F
• Where A=10, B=11, C=12, D=13, E=14, F=15

Decimal Number System

• A positional system of numeration with decimal digits and a base of ten.
• Used everyday.
• Consists of the numbers 0-9.
• example: 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 11, 12

Binary Number System

• Has '2' as it's base
• Only uses the digits '0' and '1'
• Bits of '0' and '1' are joined together to form binary numbers.
  • 1010₂
  • 1100₂

Hexadecimal Number System

• A method of representing numbers that has 16 as its base.
• Uses 16 symbols to represent values (0–9, A – F).
• Advantages:
  • Can represent binary values in a compact and readable form.
  • Conversion between binary and hexadecimal is efficient.
• Example:
  • 3AE₁₆
  • 9B4₁₆

Binary to Decimal Conversion

• Each column (from right to left) represents a binary weight .
• The column weights are 1, 2, 4, 8.

Information Coding Scheme

• ASCII - American Standard Code for Information Interchange
• EBCDIC - Extended Binary Coded Decimal Interchange Code
• UNICODE - Uniform code representing all worlds languages.

ASCII

• Uses 8 bits to represent each character.
• Can represent 256 characters (28 = 256).
• Primarily utilized on PCs and servers.

EBCDIC

• Uses 8 bits to represent a character.
• Can represent 256 characters (28 = 256).
• Primarily used on mainframes and high-end servers.

UNICODE

• Uses 16 bits to represent a character.
• Can represent 65,536 characters.
• Implemented in several OS (such as Windows, Mac OS, and Linux)

Logic Gate & Simple Logic Circuit

• Logic operations with any operations that manipulate Boolean values
• Boolean expression -> an expression that return a Boolean data type. This is also known as a logical operator
• Basic logical operators are:
  • AND
  • OR
  • NOT

AND

• Returns True (1) output when all of the inputs are True (1)
• Returns False (0) output when any @ all of the inputs are False (0)
• Boolean expressions:
  • Y=AB
  • Y=A.B
  • Y=A∩B

OR

• Returns True (1) output when any of the inputs are True (1)
• Returns False (0) output when all of the inputs are False (0)
• Boolean expressions:
  • Y=A+B
  • Y=A∪B

NOT

• Changes one logic input to the opposite output
• Returns True if its input if False
• Returns False if its input is True

Combination of Different Logical Operators

• NAND
• NOR
• XOR
• XNOR

NAND

• Combination of AND and NOT gate
• Produces True (1) output when any of the inputs are False (0)
• Produces False (0) output when all of the inputs are True (1)
• Boolean Expressions
  • Y = ~ (AB) / Y = ! (AB) / Y=(AB)
  • Y = ~ (A.B)/ Y = ! (A.B) / Y=(A.B)
  • Y = ~(A ∩ B) / Y = ! ((A ∩ B) / Y = (A ∩ B)

NOR

• Combination of OR and NOT gate
• Produces True (1) output when all of the inputs are False (0)
• Produces False (0) output when any of the inputs are True (1)
• Boolean expressions:
  • 1. Y = ! (A + B) / Y = A + B / Y = ~(A + B)

2. Y = ! (A∪B)/Y = A∪B/Y = ~(A ∪ B)

XOR

• Exclusive-OR gate / logical operation
• Returns True (1) if any of its inputs differ
• Returns False (0) if all of its inputs are all the same ✓ Y=AB

XNOR

• Exclusive-NOR gate / logical operation
• Returns True (1) if all of its inputs are the same
• Returns False (0) if any of its inputs differ
• Y=A⊕ B

Explore input devices like drawing tablets and microphones, output tech such as projectors. Learn about storage solutions like portable drives. Identify devices based on usage.