Chapter 2 - The System Unit

⧭Chapter 2: The System Unit

➹Introduction

Speed, capacity, and flexibility determine the power of personal computers.

Knowledge of a computer’s power allows you to make good buying decisions and to determine if your current system will run new applications.

Competent end users need to understand the functionality of the basic components of the system unit

➹System Unit

⇴System Chassis

Container that houses most of the electronic

components that make up a computer system

⇴System Unit

Contains system’s electronic components and

selected secondary storage devices

➹System Unit Types

1. Desktops

• System unit is in a separate case
• Tower Units
•  All-in-Ones All components including monitor

2. Laptops

•  Portable and much smaller
•  Ultrabooks – laptop and tablet in one
• Gaming – high end graphics

3. Tablets 

• Mini tablet

4. Smartphone

• Most popular device – handheld computer 
• Extend the capabilities of cell phones 

5. Wearables 

• Contain embedded computers

➹Components

• Although all devices come in many shapes and sizes they have similarities such as;
• System boards
• Microprocessors
• Memory

➹System Board

System board or main board or motherboard controls communication for the entire

computer system

⇝All components and devices connect to the system board
⇝Data path and traffic monitor
⇝Allows various components to communication efficiently with one another

➹Sockets and Chips

The system board contains a variety of electronic components

• Sockets – the connection point for chips
• Chips
• Tiny circuit boards etched onto squares of silicon
•  Also called silicon chip, semiconductor, or integrated circuit
• Mounted on chip carriers

➹Slots and Bus Lines

Additional system board components:

⇰Slots

⇰ Provide a connection point for specialized cards or circuit boards

⇰ Provide expansion capabilities for the computer

⇰ Bus lines

⇰ Connecting lines that provide pathways to support communication among electronic components

➹Microprocessor

⇴Central Processing Unit (CPU) or Processor

⇴Contained on a single chip call a Microprocessor

⇴ Brains of the computer

⇴Two Basic Components of the CPU

⇴ Control unit

⇴Tells the computer system how to carry out a

    program’s instruction

⇴ Arithmetic-logic unit (ALU)

⇴Performs arithmetic and logical operations

➹Microprocessor Chips

⇰Chip capacities are expressed in word size

⇰Word is the number of bits that can be processed at one time: 16, 32 or 64

⇰Clock Speed

⇰ Processing speed or the number of times the CPU fetches and processes data or instructions      in a second

➹Multicore Chips

⟿ Multicore Processors

⟿ Two or more separate and independent CPUs within a system unit

⟿  Quad-core supports 4 core processes

⟿  Parallel Processing

⟿  Computer’s ability to divided tasks into parts that can be

       distributed across each core

⟿  Windows 8 and Mac OS X support parallel processing

➹Specialty Processors

➤Coprocessors

➤Designed to improve specific computing operations

➤Graphics Processing Unit (GPU) / Graphics coprocessors

➤Designed to handle a variety of specialized tasks

➤3D images

➤Encrypting data

➤Standard features in gaming computers

➹Memory

 Holding area for data, instructions, and information

 Contained on chips connected to the system board

 Three well-known types of memory chips:

 RAM

 Random Access Memory

 ROM

 Read Only Memory

 Flash Memory

➹RAM

 Random Access Memory (RAM) chips hold programs and data that the CPU is presently        processing

 Volatile or temporary – contents are lost when computer is powered off

 Cache memory – temporary, highspeed holding area between the memory and CPU

 Additional RAM can be added using an expansion module called a DIMM (Dual in-line memory module)

➹RAM continued

Virtual Memory

 Dividing a program between memory and storage enabling the system to run very large programs

 Memory is expressed in bytes

➹Rom  

⥁Read-only memory (ROM)

⥁Information stored by the manufacturer

⥁ Non-volatile and cannot be changed

⥁CPU can read, or retrieve data and programs in

   ROM but the computer cannot change ROM

⥁Contain special instructions

⥁Start the computer

⥁ Access memory

⥁ Handle keyboard input

➹Flash Memory

➹Flash memory combines of the features of:

 RAM, it can be updated

 ROM, it is non-volatile

 Contains start-up information

 BIOS (basic input/output system)

 Amount of RAM

 Type of keyboard, mouse, and secondary storage devices

    connected

    Many ROM chips are being replaced by flash memory

➹Expansion slots and Cards   

Expands your system:

Capabilities                                                              

⧬ Graphics cards for high quality                        

    3D graphics

⧬ Network interface cards (NIC)

    connect devices to networks

    via cables

⧬ Wireless network cards connect

    devices to networks without

    cables

⧬SD cards

⧬Expansion cards for mobile                                 

    devices

➹Bus Lines / Bus

Connect parts of the CPU to each other and various other components on the system board

—Pathway for bits representing data and instructions

—Bus width

—Number of bits that can travel simultaneously down a bus

—Architecture and design are tied to the speed and power for the computer

—Two basic categories of buses

—System bus – connects CPU to memory

—Expansion bus – connects CPU to other components

Principle types:

—Universal Serial Bus (USB)

—Connects external USB devices onto the USB bus

—FireWire

—Primarily used to connect audio and video equipment to the system board

—PCI Express (PCIe)

—Single dedicated path for each connected device

Socket for connecting external devices to the system unit

Ports connect directly

To the system board

To cards inserted into slots on the system board

Two Types

Standard Ports

Specialized Ports 

➹Standard Ports

USB

↠Keyboards, mice, printers, storage devices

↠Ethernet

↠High speed networking

↠HDMI – High Definition Multimedia Interface

↠High definition video and audio

↠Thunderbolt

↠Provides high-speed connections

↠Can connect up to 7 separate devices through 1 port

➹Specialized Ports

Ex↣ternal Serial Advanced Technology Attachment (eSATA)

High-speed connection for external secondary storage

Musical Instrument Digital Interface (MIDI)

Connect musical instruments

Mini DisplayPort (MiniDP or mDP)

Connection to large monitors

VGA & DVI

Connections to analog and digital monitors

FireWire

High-speed connections to FireWire devices

➹Cables

Used to connect external devices to the system unit via the ports

One end of the cable is attached to the device and the other end has a connector that is attached to a matching connector on the port

 

➹Making IT Work for You ~ TV Tuners

Using Windows Media Center as a DVR

Install TV Tuner to connect your computer or cable to your computer

➹Power Supply

Computers require direct current (DC) power converting alternating current (AC) from wall outlets or batteries

⇒Desktop computers have a power supply unit in the system unit

⇒Laptops use AC adapters in the system unit

⇒Tablets and mobile devices use internal AC adapters

⇒Smartphones can use wireless charging platforms 

  

                                                   

➹Electronic Data and Instructions

Digital electronic signals

Recognized by computers

Analog signals

Continuous signal
Created by voices
Conversion must take place from analog to digital before processing can occur

➹Numeric Representation

Two-state binary system consists of only two digits called bits

On = 1; negative charge

Off = 0; no charge

Byte = 8 bits grouped together

Hexadecimal system

Uses 16 digits to represent binary numbers

(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F)

➹Character Encoding

Character encoding standards assign a unique sequence of bits to each character

ASCII

American Standard Code for Information Interchange

Used by personal computers

EBCDIC

Extended Binary coded Decimal Interchange Code

Used by mainframe computers

Unicode

New encoding due to explosion of the Internet

Uses 16 bits

Recognized by virtually all computer system

➹Careers In IT

⇏Computer technicians repair and install computer components and systems

⇏Employers look for:

⇏Certification or associate degree in computer repair

⇏Communication skills

⇏Continued education is required

⇏Computer technicians can expect to earn an annual salary of $37K to $47K