1. What You Will Learn . . .
ITMA Lecture 02
Understand how computers represent data
Understand the measurements used to describe data
transfer rates and data storage capacity
List the components inside the system unit
Inside the Computer List the components on the motherboard
How a CPU processes data
Krates Ng
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What You Will Learn . . . A Bit of Computer History
Factors that determine a microprocessors • ENIAC in 1946
performance
The types and purpose of memory in a computer 5,000 operations per sec.
system
y 1,000 sq.
1 000 sq feet
The physical connectors on the exterior of the system I/O: cards, lights,
unit switches
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(cont’) Vacuum Tube or Valve
• First commercial computer: UNIVAC I in 1951
1,905 operations/sec.
943 cubic feet
I/O: magnetic tapes, printer
Cost: US$750,000
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2. (cont’) The Birth of Apple
• IBM Personal Computer XT in 1981
• Apple I in 1976
CPU: 6502 at 1MHz
RAM: 4KB Standard, expandable to 8KB
or 48KB
Graphics: 40x20 characters
p
Cost: US$666.66
7 from www.apple-history.com 8
Apple ][ Macintosh – the Birth of GUI
Introduced in 1977 Introduced in 1984
CPU: 6502 at 1MHz, 8-bit CPU: Motorola MC68000 at 8MHz, 16 bits
RAM: start from 4KB ROM: 64KB RAM: 128KB max.
ROM: 12KB 3.5” 400KB floppy drive
Cost: US$1,298.00 Weight: 16 lbs.
Cost: US$2,495.00
Apple Macintosh commercial aired during 1984 Superbowl
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Miniaturization For More….
History on computers and technology
www.computerhistory.org
History on the Apple computers
y pp p
www.apple-history.com
www.theapplemuseum.com
Transistors
Integrated Circuits
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3. Describing Hardware Performance How Computers Represent Data
OFF ON
OFF
ON
Hardware performance refers to the amount of data a OR = 1 bit
computer can store and how fast it can process the 0 1
data = 1 Byte
OR 0 0 1 1 0 1 0 0
System Case
Socket 478 80 GB = 1 Byte
Intel Pentium 4
ATX 7200 RPM 0 1 0 0 0 0 0 1
2.4Ghz Processor
Motherboard Hard Drive
Bit (Binary digit) – On or off state of electric current;
considered the basic unit of information; represented by 1s and
0s (binary numbers)
Byte – Eight bits grouped together to represent a character (an
512 MB alphabetical letter, a number, or a punctuation symbol); 256
DDR SDRAM different combinations
Memory Module
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Bits Bytes
1000 bits = 1 kilobit (kb) 8 bits = 1 Byte
1,000,000 bits = 1 megabit (mb) 1024 Bytes = 1 Kilobyte (KB)
1,000,000,000 bits = 1 gigabit (gb) 1,048,576 Bytes = 1 Megabyte (MB)
1,073,741,824 Bytes = 1 Gigabyte (GB)
1,099,511,627,776
1 099 511 627 776 Bytes = 1 Terabyte (TB)
Kilobits per second (Kbps), megabits per second
(Mbps), and gigabits per second (Gbps) are terms
Kilobyte, megabyte, gigabyte, and terabyte are
that describe units of data used in measuring data
transfer rates terms that describe large units of data used in
Example: 56 Kbps modem
measuring data storage
Example: 20 GB hard drive
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Representing Characters: Character Codes
Example
Character codes translate numerical data into characters
readable by humans
Convert 13,467,823 bytes into MB American Standard Code for Information Interchange
(ASCII) – Eight bits equals one character; used by
minicomputers and personal computers
1. 13,467,823/1024 = 13152.2 KB Extended Binary Coded Decimal Interchange Code
( ) g
(EBCDIC) – Eight bits equals one character; used by mainframe
q ; y
computers
2. 13,152.2 KB/1024 = 12.84 MB Unicode – Sixteen bits equals one character; over 65,000
combinations; used for foreign language symbols
ASCII =4
0 0 1 1 0 1 0 0
EBCDIC =4
1 1 1 1 0 1 0 0
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4. The System Unit
ASCII and EBCDIC Code
The system unit is a boxlike case that houses the computer’s
main hardware components
A footprint is the space taken up on the desk by the computer
Form factor refers to the way the internal components are
mounted in the unit
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Types of System Units Inside the System Unit
Desktop Notebook Motherboard (mainboard) – Large
printed circuit board with thousands of
electrical circuits
Power supply – Transforms
alternating current (AC) from wall
outlets to direct current (DC) needed
by the computer
Cooling fan – Keeps the system unit
cool
Internal Speaker – Used for beeps
when errors are encountered
Drive bays – Housing for the
Personal Digital
computer’s hard drive, floppy drive,
Assistant and CD-ROM / DVD-ROM drives
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The Motherboard The Central Processing Unit:
The Microprocessor
The motherboard provides the
centralized connection point
for the computer’s components
Most components are
integrated circuits (chips)
Chips carry electrical current
and contain electronic CPU
switches or transistors
CPU socket
Central processing unit (CPU) – A microprocessor that
interprets and carries out instructions given by software. It
controls the computer’s components
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5. Components of the CPU Intel P4 (1)
Control unit – Coordinates and controls all parts of
the computer system
Arithmetic-logic unit – Performs arithmetic or
logical operations
Registers – Temporarily store the most frequently
used instructions and data
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Intel P4 (2) Moore’s Law
In 1965, Gordon Moore said “The complexity for min. component costs has
increased at a rate of roughly a factor of two per year…”
www.intel.com/technology/mooreslaw/index.htm
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The Control Unit
The Arithmetic-Logic Unit
The control unit manages four basic operations (fetch,
decode, execute, and write-back)
The four-step process is known as the machine cycle or
processing cycle The arithmetic-logic unit (ALU) performs basic
The processing cycle consists of two phases: arithmetic and logic operations
Instruction Cycle Adds, subtracts, multiplies, and divides
– Fetch – Gets the next program instruction from the computer s
computer’s
memory Compares alphanumeric data
– Decode – Figures out what the program is telling the computer to
do
Execution Cycle
– Execute – Performs the requested action
– Write-back (Store) – Writes (stores) the results to a register or to
memory
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6. Microprocessor Performance Microprocessor Performance
Data bus width – The number of pathways within Operations per cycle (clock speed) – The number of
the CPU that transfer data; they are measured in bits clock cycles per second measured in megahertz (MHz)
(8, 16, 32, or 64) or gigahertz (GHz)
Word size – The maximum number of bits of data Superscalar operations – Carrying out more than one
that the CPU can process at one time (8 bits, 16 bits,
bits bits instruction per clock cycle
32 bits, or 64 bits) Pipelining operations – Feeding a new instruction into
System Clock – electronic circuit that generates the CPU at every step of the processing cycle
pulses at a rapid rate and synchronizes the computers
internal activities
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Parallel Processing Popular CPUs
Intel Advanced
Parallel processing involves using more than one CPU to Micro Devices
Pentium MMX
improve performance Pentium IV (AMD)
Complex instruction set computer (CISC) – A chip that
includes special-purpose circuits that carry out instructions at
high speeds
Pentium III
Reduced instruction set computer (RISC) – A chip with a
bare-bones instruction set that results in a faster processing Cyrix Motorola (Apple)
speed than CISC chips
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The Chipset Input/Output Bus
PCI slots
The input/output bus provides a
pathway so that the
microprocessor can communicate
with input/output devices
An input/output bus contains
expansion slots which hold
expansion cards
PCI (Personal Computer
Interface) slots are receptacles in
A chipset is a collection of chips that provide the which expansion cards are
switching circuitry needed to move data throughout the inserted. They support Plug and
computer Play (PnP) devices. Expansion
Card
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7. Memory Virtual Memory
Read-Only FULL
Memory (ROM)
Random Access
Memory (RAM) Flash Memory Virtual memory:
Part of the hard disk is reserved as RAM
Memory is the term used to describe devices that enable the When RAM modules become full, the CPU accesses the
computer to retain information. Program instructions and data hard disk to store and retrieve data
are stored in memory chips for quick access by the CPU.
Virtual memory is slower than RAM
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Random Access Memory (RAM) Types of RAM
Dynamic RAM (DRAM) – A memory chip that needs to
be refreshed periodically or it will lose its data
Synchronous DRAM (SDRAM) is synchronized with the
computer’s system clock
RAM is a type of memory that stores information temporarily Rambus DRAM (RDRAM) uses a fast bus to send and
so that it’s available to the CPU receive data within one clock cycle. It is faster than
RAM is volatile; the memory’s contents are erased when the SDRAM
power is turned off Double data rate SDRAM (DDR SDRAM) is a type of
Each byte of memory has a unique location or memory SDRAM that can send and receive data within one clock
address cycle
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Processing a Word Cache Memory
CLICK ONCE TO
BEGIN ANIMATION
MONITOR WE B
RAM
KEYBOARD
W E B B P i h (Level
Primary cache (L l 1 or L1) – L Located within the CPU
d i hi h
E chip, it is the memory that the microprocessor uses to store
W frequently used instructions and data
Secondary cache (Level 2 or L2; Backside Cache) – Located
near the CPU, it is the memory between the CPU and RAM
CPU Cache memory is faster than RAM
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8. Outside the System Unit Types of Connectors
Point and click on a connector below to view information about it.
Click again to remove the text.
Drive bays
On/off switch
Reset button
BACK
Indicator lights
FRONT
The front panel contains drive bays, various buttons,
and indicator lights
VGA port (keyboard flows–throughspeed access for cardto be
Sound – A Data port) Also called to to connect
– connector high serial port to after
Game port Data flows a – Allows pulses, monitorsmouse. transfer
Parallelcard connectors Special serialjacks, allowing thekeyboard.
Universal (mouse A 15 –infor serieseightport127 devicesanother oneof
PS/2 connector – port) pin–connector used foroneconnectconnectorsbit
Serial portSerial Bus (USB)Specialof upwiressound graphics-intensive
Connectors and ports are physical receptacles located eight bits slowmini-plugs. Microphone, than serial ports.
connected at a data transfer rate. fasterline-in, line-out, and speaker
accept stereo time.
interaction.
at a time; of data simultaneously;
on the back to connect peripheral devices to the connectors are plugged into the card.
computer
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Other Types of Connectors Additional Ports and Connectors
Small computer system interface (SCSI) port – A Telephone – modem interface
parallel interface that enables up to eight devices to Network – larger than telephone jack
be connected to it PC card slot – notebook computers have slot for PC
1394 (FireWire) port – A high-speed connection for cards
up to 63 devices
p Sound card connectors –
Infrared Data Association (IrDa) port – Infrared Mic – microphone input
Line In – input from audio devices
signals are used to communicate between peripheral
Line Out – output to another audio device
devices and the system unit
Speaker – output to external speakers
TV/sound capture – turns computer into a TV tuner
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Summary Summary (continued)
• The basic unit of information is the bit
• The CPU’s performance is measured by the data bus width,
• Large units of data are called kilobytes (KB), megabytes (MB), operations per second, speed, and cache memory
gigabytes (GB), and terabytes (TB)
• The system unit contains the motherboard, which is a circuit • Random access memory (RAM) is the computer’s main memory.
board that provides receptacles for chips and input/output buses It is volatile.
• The central processing unit (CPU) contains the control unit (CU) • There are various types of RAM including dynamic RAM
RAM,
and the arithmetic-logic unit (ALU). It manages the four basic (DRAM), synchronous DRAM (SDRAM), Rambus DRAM
operations (fetch, decode, execute, and write-back). (RDRAM), and double data rate (DDR) SDRAM
• The CPU processes data in a four-step cycle called a machine • Computers have ports such as serial ports, parallel ports, SCSI
cycle. The CU manages four basic operations: fetch, decode, ports, USB ports, FireWire ports, and IrDA ports to connect
execute, and store. input/output devices
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9. What You Will Learn About
The purpose of special keys and the most frequently
used pointing devices
The characteristics of a monitor’s quality and the various
types of monitors
Input/Output and Storage
The two major types of printers
The difference between memory and storage
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What You Will Learn About Input
Input is any data entered into the computer’s
The categories of storage devices
memory
The performance characteristics of hard drives
How data is stored on both hard and floppy disks
The various optical storage media available for
personal computers
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Input Devices: Giving Commands Keyboard
Keyboard
Mouse
Other Pointing
The keyboard allows the computer user to enter
Devices words, numbers, punctuation, symbols, and special
function commands into the computer’s memory
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10. Types of Keyboards The Mouse
Enhanced / Extended Keyboard Wireless
Ergonomic Keyboard Ergonomic Keyboard
Enhanced or Extended keyboard – Typically 101 keys The mouse is the most widely used pointing device
laid out in the QWERTY fashion; connected to the
computer by a cable A mouse is palm sized
Cordless keyboard – Uses infrared or radio wave signals As the mouse is moved, its movements are mirrored by the on-
Ergonomic keyboard – Designed to help prevent screen pointer
Repetitive Strain Injury, or RSI
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Types of Mice Other Types of Pointing Devices
Wheel Cordless
Mouse Mouse Touch
Trackball Screen
Pointing Joystick
Stick
Sti k
Wheel mouse – Contains a rotating wheel used to scroll
vertically within a text document; connects to PS/2 port or
USB port
Tablet
Cordless mouse – Uses infrared signals/RF/Bluetooth to Touch Pad Pen
connect to the computer.
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Using the Mouse Audio Input: Speech Recognition
Speech recognition is a type
Mouse buttons enable the user to initiate actions of input in which the
computer recognizes words
Clicking (left-, right-, or double-clicking) allows the
spoken into a microphone
user to select an item on the screen or open a program
or dialog box Special software and a
microphone are required
i h i d
Click and drag – Holding down the left mouse button
and moving the mouse enables the user to move Latest technology uses
continuous speech recognition
objects on the screen
where the user does not have
to pause between words
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11. Alternative Input Devices Monitors
Scanners
CRT LCD
Flatbed Barcode reader
A monitor is a peripheral device which displays
computer output on a screen
Screen output is referred to as soft copy
Types of monitors:
Cathode-ray tube (CRT)
Liquid Crystal Display (LCD or flat-panel)
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Cathode-ray tube (CRT) Liquid Crystal Display (LCD)
Cells sandwiched between two transparent layers
form images
Resemble televisions Used for notebook computers, PDAs, cellular phones,
Use picture tube technology and personal computers
Less expensive than a LCD
p More expensive than a CRT monitor
monitor
Take up more desk space and Take up less desk space and use less energy than
use more energy than LCD CRT monitors
monitors
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Monitor Specifications Printers
A printer is a peripheral
device that produces a
Screen size – The diagonal measurement of the screen surface physical copy or hard
in inches (15, 17, 19, 21) copy of the computer’s
Resolution – The sharpness of the image determined by the output
number of horizontal and vertical dots (pixels) that the screen
can display (800 x 600, 1024 x 768, 1600 x 1200)
Refresh rate – The speed at which the screen is redrawn
(refreshed) and measured in Hertz (Hz) (60Hz, 75Hz)
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12. Types of Printers Plotter
Inkjet Laser
Inkjet printer also called a
printer, Laser printer works like a
bubble-jet, makes characters copier
by inserting dots of ink onto Quality determined by dots A plotter is a printer that uses a pen that moves over a
paper per inch (dpi) produced large revolving sheet of paper
Letter-quality printouts Color printers available
Cost of printer is inexpensive Expensive initial costs but
It is used in engineering, drafting, map making, and
but ink is costly cheaper to operate per page seismology
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Memory vs. Storage
Why Is Storage Necessary?
Hard Drive – storage RAM – memory
Storage devices:
Retain data when the computer is turned off
Storage,
Storage also known as mass media or auxiliary storage,
storage Are cheaper than memory
refers to the various media on which a computer system can Play an important role during startup
store data
Are needed for output
Storage devices hold programs and data in units called files
Memory is a temporary workplace where the computer
transfers the contents of a file while it is being used
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Hard Disks
A Bit of HD History
Platter Read/Write
• Guess how big this HD can store? head
Hard disks are high speed, high capacity storage devices
high-speed high-capacity
They contain metal disks called platters
They contain two or more stacked platters with read/write
heads for each side
IBM System 305: 1st computer with a hard drive in 1956 Hard disks can be divided into partitions to enable computers
to work with more than one operating system
There were 50 24”∅ platters and could store 5MB!!!
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13. More Hard Drives (I) More Hard Disks (II)
Removable Hard Disks (getting outdated)
Getting smaller (physical size) :
Platter is enclosed in a cartridge e.g. Toshiba 0.85” 2-4GB HD in 2004.
Can be inserted into a drive bay
Secondary storage – storage that isn’t directly available And bigger (storage size) :
gg ( g )
e.g. Hitachi 3.5” 1TB HD in 2Q 2007.
Internet Hard Drives
Storage space on a server
Or Both :
Subscription service e.g. Fujitsu 2.5” 300GB 4200rpm HD (MHX2300BT) in Feb. 2007
e.g. Toshiba 1.8” 100GB 4200rpm HD in Jan. 2007
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More Hard Disks (III) Factors Affecting a Hard Disk’s Performance
Spins faster :
e.g. Seagate’s 2.5” Savvio 15K Series HD 36GB/73GB at 15,000rpm. Seek time or positioning performance – How
quickly the read/write head positions itself and
begins transferring information. It is measured in
Flash-memory based HD (Solid State Disks SSD) milliseconds (ms)
e.g. SanDisk’s 32GB 1.8” SSD in Jan. 2007 at about US$600.00 Spindle speed or transfer performance – How
quickly the drive transfers data. It is measured in
rotations per minute (RPM)
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Floppy and Zip Disks and Drives Protecting the Data on Your Disks
Floppy Drive Zip Drive
Don’t touch the surface of the disk
Don’t expose disk to magnetic fields
Avoid contamination (food, drink)
Floppy Disk Avoid condensation
A di k or diskette is a portable storage medium
disk di k i bl di
High-density floppy disks that are commonly
Avoid excessive temperatures
used today store 1.44 MB of data
Disks work with a disk drive
Zip disks store up to 750 MB of data and are not
downwardly compatible with floppy disks
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14. CD-ROM Discs and Drives CD-R and CD-RW Discs and Recorders
CD-ROM stands for Compact Disc- CD-R CD-RW
Read Only Memory Discs can be read and Discs can be read and
CD-ROM drives can not write data written to written to
to discs Discs can only be Discs are erasable
They are capable of storing 650 MB written to “once” Discs can be written to
of data CD-R drives are capable many times
They are used for storing operating of reading and writing CD-RW drives are
systems, large application programs, data capable of reading,
and multimedia programs writing, and erasing data
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DVD-ROM Discs and Drives DVD-RW and DVD+RW Discs
DVD stands for Digital Video DVD-R and DVD+R drives have the ability to
Disc read/write data
DVD technology is similar to DVD-RW and DVD+RW drives allow you to write,
CD-ROM technology erase, and read from a disc many times
DVDs are capable of storing up
to 17GB of data
The data transfer rate of DVD
drives is comparable to that of
hard disk drives
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Protecting Data on Discs The Future of Optical Storage (1)
Do not expose discs to excessive heat Blu-Ray Disc (BD)
Do not touch underside of discs 140 members: Sony, Samsung, LG, Walt Disney
Pictures, Twentieth Century Fox …etc.
Do not write on the label side of discs with a
25GB/50GB
hard instrument
Single layer can hold >2 hrs. of HDTV
2
Do not stack discs blue-violet laser (405nm)
Store discs in original
boxes
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15. The Future of Optical Storage (II) Solid State Storage Devices
HD DVD
Solid state storage devices use nonvolatile memory
Developed by Toshiba and NEC
chips to retain data
15GB/30GB
They do not have moving p
y g parts
They are small, lightweight, reliable, and portable
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Solid State Storage Devices Summary
Memory • Input is the software, data, and information that is
Smart Stick entered into the computer’s memory
Card
• Input devices such as the keyboard, mouse, and
trackball enable the user to enter data
Secure Digital Compact • A pointing device enables the user to control
(SD) M
Memory Flash (CF)
Memory
movements of an on-screen pointer
f i
• Speech recognition software enables the user to
enter data into a computer by speaking into a
microphone
• Monitors enable the user to view the computer’s
USB Thumb
processed data; the output is known as soft copy
Drives
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Summary (continued)
Summary (continued)
• The two types of monitors are the CRT and the LCD • A hard disk’s performance is measured by its positioning
• A monitor’s quality is measured by screen size, resolution, and performance and transfer rate
refresh rate • Optical storage devices include:
• Printers produce permanent versions (hard copies) of the CD-ROM– Read-only
computer’s output
CD-R– Record once
• The two basic types of printers are the inkjet and laser
CD-RW– Erasable, write repeatedly
• M
Memory makes software and d t available for the CPU’s use
k ft d data il bl f th CPU’
DVD-ROM/DVD+ROM – Read-only
• Storage devices are categorized by:
DVD-R/DVD+R– Read/write
Read-only
DVD-RW/DVD+RW – rewritten many times
Read/write
• Solid state storage devices include:
Random access
PC cards
Near online (secondary)
Flash memory cards
Smart cards
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