Download The CPU - Faculty

Chapter 1
How Computers
Work
You Will Learn…
• That a computer requires both hardware and
•
•
software to work
About the many different hardware
components inside and connected to a
computer
How the CPU works and how it communicates
with other devices
Hardware Needs Software
to Work
• Hardware

Physical components of the computer (monitor,
keyboard, memory chips, hard drive)
• Software

Set of instructions that directs hardware to
accomplish a task
Hardware Needs Software
to Work
Functions of the Microcomputer
Binary Number System
• Technology of storing and reading only two
•
•
values: on and off
Bits and bytes
Originated in the 1940s by John Atanasoff
Binary Number System
Binary Number System
PC Hardware Components
• Input/output devices: outside computer case
• Processing and storage components: inside the
•
case
Elements required by hardware devices to
operate:

Method for CPU to communicate with it
 Software to instruct and control it
 Electricity to power it
Hardware Used for
Input and Output
• Connects to computer case by ports
• Most popular input devices:

Keyboard
 Mouse
• Most popular output devices:

Monitor
 Printer
Ports
Input Devices
Output Devices
Hardware Inside the Case
• Motherboard (contains CPU, memory, etc.)
• Floppy drive, hard drive, and CD-ROM drive
•
(permanent storage)
Power supply with cords supplying electricity
to all devices inside the case
continued…
Hardware Inside the Case
•
Circuit boards (used by CPU to communicate with
devices inside/outside the case)

•
Contain microchips, which are most often manufactured
using CMOS (complementary metal-oxide semiconductor)
technology
Cables that connect devices to circuit boards and the
motherboard


Data cables
Power cables (or power cords)
Peripheral Devices
• Communicate with CPU but are not located
•
directly on the motherboard
Some are linked by expansion cards in
expansion slots on the motherboard
The Motherboard
•
•
Largest, most important circuit board in the computer
Contains the CPU, with which all devices must
communicate:

Installed directly on the motherboard
 Linked by a cable connected to a port on the motherboard
 Indirectly linked by expansion cards
•
Also called the main board or system board
The Motherboard
Ports on a Motherboard
Major Components on All
Motherboards
•
For processing:

•

CPU
Chip set

RAM
Cache memory
Electrical system:

Power supply
connections
For communication with
other devices:


For temporary storage:

•
•
•

Traces
Expansion slots
System clock
Programming and setup
data:


Flash ROM
CMOS setup chip
The CPU
•
•
Most important chip
(the microprocessor)
Performs most of actual
data processing
The Chip Set
• Controls flow of data and instructions to and
•
from the CPU
Provides careful timing of activities
The Chip Set
CPU and Chip Set Manufacturers
• IBM-compatible PCs


Intel Corporation
AMD
VIA
SiS
Cyrix

Motorola Corporation



• Macintosh (Apple Computer, Inc.)
Storage Devices
• Temporary (primary storage, or memory)

Temporarily holds data and instructions while
processing them
 Faster to access than permanent storage
• Permanent (secondary storage)

Data and instructions must be copied into primary
storage (RAM) for processing
Primary and Secondary Storage
Primary Storage Devices
•
Memory, or RAM, located on motherboard and other
circuit boards

•
Volatile versus nonvolatile (or ROM) memory
Common types of boards that hold memory chips



SIMMs (single inline memory modules)
DIMMs (dual inline memory modules)
RIMMs (memory modules manufactured by Rambus, Inc.)
RAM Chips
Types of RAM Modules
Secondary Storage Devices
• Hard disks
• Floppy disks
• Zip drives
• CD-ROMs
• DVDs
Hard Drive
•
•
•
Uses EIDE (Enhanced
Integrated Drive
Electronics) technology
Motherboard can
accommodate up to four
IDE devices on one system
IDE provides two
connectors on a
motherboard for two data
cables
Motherboard with Connectors
A Typical System
Hard Drive’s Power Supply
Floppy Drive Cable
Floppy Drive Connection
CD-ROM Drive
Motherboard Components Used for
Communication Among Devices
• The bus

System of pathways used for communication and
the protocol and methods used for transmission
 Includes a data bus, address bus, and control bus
Bus Lines
Data Bus
System Clock
• Synchronizes activity on the motherboard
• Sends continuous pulses over the bus that are
•
used by different components to control the
pace of activity
Frequency of activity is measured in MHz,
or 1 million cycles per second
System Clock
Bus Lines
•
•
Lines of a bus, including data, instruction, and power
lines, often extend to the expansion slots
Types of expansion slots

PCI (Peripheral Component Interconnect)
•

AGP (Accelerated Graphics Port)
•

For high-speed input/output devices)
For a video card
ISA (Industry Standard Architecture)
•
Used by older and/or slower devices)
Bus Lines
Types of Expansion Slots
Interface (Expansion) Cards
• Enable CPU to connect to external device or to
a network
Interface (Expansion) Cards
Full View of a Video Card
The Electrical System
•
Power supply



Most important component of
computer’s electrical system
Converts/reduces electricity to
voltage the computer can
handle
Runs a fan directly from
electrical output voltage to
cool inside of computer case
Electrical System
Electrical System
Instructions and Data Stored on the
Motherboard
•
ROM BIOS


•
Holds software needed to start up PC and begin loading an OS
Most are flash ROM
CMOS chip

Stores setup (configuration) information
•

Setup information can also be set by means of jumpers and DIP (dual
inline package) switches
Powered by a battery on motherboard when power is off
ROM BIOS Chip
ROM BIOS Chip
CMOS Chip
Using Jumpers
DIP Switches
How a CPU Works and Communicates
with Other Devices
• Responsible for most processing
• Depends on chip set, system clock, and buses
•
to move data to and from I/O devices, memory,
and secondary storage
Only two states: on and off
Components of a CPU
• Input/output (I/O) unit

Manages data/instructions entering/leaving CPU
• One or more arithmetic logic units (ALU)

Does all comparisons and calculations
• Control unit

Manages all activities inside CPU itself
Components of a CPU
How the CPU Works
• Registers hold data and instructions while it
•
•
processes them
Memory cache holds data and instructions just
before they are processed
Internal bus runs at different speed than
external bus
How the CPU Uses Memory
• CPU accesses memory by way of the data bus
How CPU and Devices Use System
Bus to Communicate
The Address Bus
The Control Bus
•
•
•
•
System clock control line

Provides timing for motherboard components
Interrupt request (IRQ) lines

Used by devices to get CPU’s attention; assigned at startup
Read/write control lines

How to use address on address bus (read or write operation)
I/O control lines

How to use address lines (memory addresses or I/O
addresses)
Interrupt Request (IRQ) Lines
I/O Control Lines
Understanding Binary
• With computers, everything is binary; every
•
process is a series of zeros and ones
Decimal and hexadecimal notations are two
shorthand ways of displaying binary numbers
Understanding Binary
• Hexadecimal notation (hex)

Shorthand way to display long binary numbers;
easier for humans to understand
 Built on multiples of sixteen
• ASCII (American Standard Code for
Information Interchange) standard

Has assigned an 8-bit code for letters, symbols, and
other characters
Computer Terminology
Chapter Summary
• An introduction to the inside of the computer
• Initial insight into how hardware components
•
•
of a computer system work
How a CPU works and communicates with
other devices
Understanding binary