Overview of Computer
Hardware
CS 1 Introduction to Computers and Computer
Technology
Rick Graziani
Fall 2006
Hardware Components
INPUT
Know these!
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SYSTEM UNIT
OUTPUT
PERMANENT
STORAGE
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The System Unit
Let’s open the box!
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The System Unit
circuit board = a board with
integrated circuits
(microchips)
• system board or
motherboard
• interface boards or expansion
boards
system board or motherboard
= a single circuit board with
the components which make
up the computer’s processor
for a microcomputer, including
the:
• CPU (Central Processing
Unit)
• Memory
– RAM
– ROM or ROM BIOS
• Rickexpansion
slots
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The System Unit
circuit board = a board with integrated circuits (microchips)
• system board or motherboard
• interface boards or expansion boards
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The System Unit
system board or motherboard = a single circuit board with the
components which make up the computer’s processor for a
microcomputer, including the:
• CPU (Central Processing Unit)
• RAM
• ROM or ROM BIOS
• expansion slots
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The System Unit
Interface board/card (or Expansion board/card)- used
to connect peripheral devices (monitor, printer, etc.) to
the motherboard (more on this “later”)
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The System Unit
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The System Unit
Inserting an Interface card or Expansion board into an expansion
slot of the motherboard
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The System Unit
•
•
•
Integrated Circuits (microchips) What can they do?
1. Store bits: store the data and instructions used for
processing
Example: RAM and ROM chips (later)
2. Process bits: process the
data and instructions
Example: CPU (next)
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The CPU- The Real Computer
CPU (Central Processing Unit)= A complex collection of electronic
circuits on one or more integrated circuits (chips) which:
1. executes the instructions in a software program
2. communicates with other parts of the computer system, especially
RAM
The CPU is the computer!
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Some of the parts of the CPU
Arithmetic Logic Unit (ALU) = area of the CPU responsible for the actual
processing
“The CPU’s calculator”
Control Unit (CU) = area of the CPU responsible for getting data and
instructions from RAM
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What is in charge of the CPU?
The operating system software! The “OS”
Windows XP, Macintosh OS, Linux/UNIX, etc.
The operating system manages what programs and data the CPU will be
working on.
More Later on Operating Sys.!
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A CPU can be:
A CPU can be:
1. A series of integrated circuits (chips) on one or more circuit boards
– Older mainframe and minicomputers
2. On a single integrated circuit known as a microprocessor
microprocessor = a CPU on a single chip
microcomputer = older term for a computer with a microprocessor(s)
(PC, Macintosh)
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The Microprocessor (again)
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The Microprocessor
Compatibility
Why can’t I run Windows software on my Macintosh and visa versa?
• Operating system software is designed to run on one specific type of
CPU or “family of CPUs”
• Application software is designed to work with a specific operating
system software, thus one specific type of CPU or “family of CPUs”
More “later”
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RAM- Primary Memory
RAM (Random Access Memory) = integrated circuits (chips) used to
temporarily store software (programs, instructions) and data
• “primary” storage for the CPU
• electronic switches, storing ON’s and OFF’s
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RAM – Primary Memory (storage)
Temporarily stores for the CPU:
Software
• operating system software
• application software
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Data
• documents, spreadsheets, etc.
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RAM
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Inserting RAM onto the motherboard
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RAM - Volatile
RAM is TEMPORARY memory
RAM is volatile
• stores ON and OFF bits (software and data) electrically
• when power goes off, everything in RAM is lost
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RAM - Speed
Why does the CPU use RAM?
• The CPU is very FAST!
• The CPU needs the instructions (software) and data as quickly as
possible
• If the CPU has to wait, so does the user
Why doesn’t the CPU use permanent storage like disk drives?
• Too slow
• EXAMPLE: Spellchecker
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RAM - Capacity
The amount of RAM determines:
• What software and data the user can work on
• how much software and data the user can work with
“Not enough memory” error message from the Operating System
• The more complex and sophisticated the software, the more
instructions that software contains, which means larger software files.
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RAM - Capacity
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RAM – Temporary Storage
If RAM is temporary where is the data and software stored permanently?
Permanent storage devices such as:
• hard disk drives
• floppy disks
• CD ROM disk
• Flash sticks
(“later”)
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Example: Typing a document in Microsoft Works
In RAM memory
• MS (Microsoft) Windows XP operating system or
Macintosh OS
• MS Words
• the document
What the user sees on the screen is being stored in RAM
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CPU
RAM
ROM
256
MB
Hard Disk Drive
Operating System Software
“The kernel”
Application Software
MS Word
User data (information)
0
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ROM - Read Only Memory
ROM (Read Only Memory) = integrated circuits (microchips) that are used
to permanently store start-up (boot) instructions and other critical
information
Read Only = information which:
• cannot be changed
• cannot be removed
• cannot be appended (added to)
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ROM - Read Only Memory
ROM is sometimes known as ROM BIOS (Basic Input Output System
software)
ROM permanently contains:
• start-up (boot) instructions
• instructions to do “low level” processing of input and output devices,
such as the communications with the keyboard and the monitor
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ROM - Read Only Memory
Firmware = software program which is stored permanently on a
microchip, such as the software on the ROM chip
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Booting up the computer
Booting the computer = starting the
computer
Four phase of the boot process: S.P.I.T.
1. System Start-up
2. Power On Self-Test (POST)
3. Initialization
4. Transfer to the operating system
software
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1. System Start-up
•
•
•
•
Turning on the computer
Power supply supplies electricity to the computer
The ROM chip boot instructions (firmware) is now “in charge”
ROM chip instructions processed by the CPU
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2. Power On Self-Test
The ROM chip boot instructions tests the “processor” including:
• checks the CPU
• tests RAM memory and calculates it’s capacity
• checks other components on the motherboard
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3. Initialization
The ROM chip boot instructions checks the “peripheral devices”
including:
Input devices
• keyboard, mouse
Output devices
• monitor, printer
Storage devices
• hard disk
• floppy drives
• CD ROM drive
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What is a peripheral device?
A device which is connected to the computer’s processor, including
input, output, and storage devices.
(More later)
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4. Transfer to an operating system
software
• The ROM chip boot instructions are now finished
• The ROM chip wants to give control over to an operating system
•
software
The ROM chip searches for the operating system (usually on the hard
disk drive) and transfers an operating system file (the kernel) into RAM
memory
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Booted up
The operating system software is now in charge!
• The operating system file, known as the kernel, is in RAM memory
• The user may now access application programs and data (double click
on MS Word)
• The operating system software is in charge
(More later)
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Inside the CPU
The CPU
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CPU
• The CPU is the brains of the computer.
• The CPU is the computer!
• The CPU decision is the most important decision you will need to make
•
in purchasing a computer.
Operating system software and application software requires a
minimum type of CPU (don’t limit yourself in your purchase)
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The Operating System Software and the CPU
• OS manages the CPU
• OS manages what the CPU will work on and when
• The user can only take advantage of the complete abilities of the CPU
only if the operating system software and application software also
have those abilities.
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Tighter
Circuitry
• Closer the circuits are together, the more circuits that can fit on a
•
•
single chip
Faster performance when there are fewer chips
Moore’s Law: Gordon Moore, chairman of the board of Intel in the
1960’s stated that transistor densities on a single chip would double
every 18 months
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Power of the CPU
1. The number of bits processed
2. The size of the CPUs data bus
3. The Speed of the CPU
4. Internal Cache
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1. The number of bits processed
Toll Booth Analogy
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1. The number of
bits processed
Early microprocessors:
• 4 bit and 8 bit processors
• Intel 8088, 80286: 16 bit processors
• Intel 80386, 80486, Pentium: 32 bit processors
• Motorola (Apple) 68020, 30, 40 and the PowerPC: 32 bit processors
Current processors
• 32 bit processors
Latest:
• 64 & 128 bit processors
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Pentium III
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Pentium 4
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AMD Processors (continued)
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VIA C3 Processor
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64-Bit Processors
•
Intel Itaniums
• AMD 64-bit processors
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The Itanium 2 Processor
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AMD 64-Bit Processors
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CPU Heat Sinks and Cooling Fans
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Combination Heat Sink and Cooling Fan
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2. The CPU’s Data Bus
•
Toll Booth
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2. The CPU’s Data
Bus
Data bus = the number or wires between the CPU and RAM
More wires (lanes) the faster the CPU gets the data and software to
process
Older CPUs: 8 and 16 bit data bus
Newer CPUs: 32 and 64 bit data bus
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The OS also plays a part!
Amount of RAM recognized by the Operating System
• Windows 95: 1GB
• Windows 98: 1GB
• Windows 98SE: 1GB
• Windows ME: 1.5GB
• Windows NT: 4GB
• Windows 2000 Professional: 4GB
• Windows XP Home: 4GB
• Windows XP Professional: 4GB
• OS X: 8GB due to current hardware limitations
• OS 9.x: 1.5GB (no single application can utilize more than 1GB)
• Linux: 64GB
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3. The Speed of the CPU
Speed measured in
• megahertz (MHz) - the number of millions of beats per second
• gigahertz (GHz) - the number of billions of beats per second
Examples:
• Early CPUs: 4 - 33 MHz
• Current Processors: 3 GHz and more
Faster the CPU, faster the processing (Toll Booth)
Cost $$$ and Manufacturing
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3. The Speed of the CPU
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4. Internal Cache
Internal Cache = memory inside the CPU chip which stores instructions
and data which the CPU is currently working on or may soon need.
• The CPU must deliver its data at a very high speed.
• The regular RAM cannot keep up with that speed.
• Therefore, a special RAM type called cache is used as a buffer temporary storage.
• L1 Cache – Same chip as CPU (fastest)
• L2 Cache – Separate chip
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Apple G5
•
•
G5 drives the largest performance gain in the history
of the PowerPC.
The 64-bit G5 offers speeds up to 2.5GHz and can
address up to 8GB of main memory.
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Intel Duo Processor
•
•
•
•
Two CPUs in one.
Which means it can run at a slower clock speed without
sacrificing performance.
– Two oxen better than one.
Less power consumed, runs cooler.
4 MB shared L2 cache.
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Storage Devices
Permanent Storage
INPUT
PROCESSOR
OUTPUT
PERMANEN T
STORAGE
• What is in charge of permanent storage
•
devices?
The operating system software!
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Cost v.s. Speed
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Direct Access Devices vs. Sequential Access
Analogy:
• Record/CD vs. Cassette Tape
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Sequential Access Devices
Sequential Access = In order to access specific information, the
device must sequentially pass through all preceding information
• 9 Track Tape (Reel to Reel)
• Cartridge Tapes
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Reel to Reel Tape (9 Track Tape)
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Using a Cartridge Tape Drive
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Storing Data on Tape
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Storing Data on Tape
Recording information
• Bits are recorded as positive and negative polarity on
magnetic tape (“magnetic media”)
Advantages
• inexpensive
• durable
• portable
Disadvantages
• slow access rate
Primary Use
Backing up “on-line” information
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Direct Access Devices
Direct Access = The specific information is accessed directly
Examples
• floppy disk drives
• hard disk drives
• cartridge disk drives
• CD ROM and DVD drives
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Floppy Disks
Floppy Disk = iron oxide coating on a portable mylar plastic disk
Becoming obsolete
Old 5 1/4 inch diskettes (FYI)
• double density = 360K capacity
• high density = 1.2 MB capacity
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Floppy Disks
Newer 3 1/2 inch diskettes
• double density = 720K capacity
• high density = 1.4 MB capacity
(Right drive for the right densities)
Advantages of 3 1/2 inch
• size, capacity, speed, durability
Notch with slide = write protection
• closed = Read/Write
• open = Read Only
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Recording information
•
Bits are recorded as positive and negative polarity on
magnetic tape (“magnetic media”)
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Magnetic Media is sensitive to:
• temperature
• magnets
• touch, smoke, dirt
• folding, bending, pressure
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Hard Disk Drives
Hard Disk = Iron oxide coating on one or more rigid
aluminum disks called platters
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Hard Disk Drives
Common Sizes
Older Disks
• 5 MB, 10 MB, 20 MB, etc.
Newer Disks
• 50 GB and more!
• Smaller, cheaper and faster!
Advantages of Hard Disk Drives
over Floppy Disk Drives
• more capacity
• faster access
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How data is stored on disks
Hotel analogy
•
•
What is in charge of storing information on the hard
disk drive (and other storage devices)?
The operating system software!
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How data is stored on disks
track = a series of concentric rings on the disk
• A track is divided into several sectors
(track) sector =a section of a track which stores a
predetermined number of bytes (bits)
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How data is stored on disks
Several sectors are combined to create clusters or blocks
cluster (Windows and Macs) or block (UNIX) = The number of
sectors which is allocated on the disk each time a file needs
space on the disk.
Windows 95 (later versions) and Windows 98 using FAT32
 1 cluster = 8 sectors (4K bytes)
 Recognizes disk drives up to 2 terabytes (2 trillion bytes)
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How data is stored on disks
FAT (File Allocation Table) and Directory = A file, a table, which is
found on one of the first sectors of every diskette and hard disk drive
(created when the disk is formatted), and contains information
regarding every file stored on that disk including the file name, the
date and time that file was created or modified, the size of the file, and
which sectors are allocated for that file.
Example
Creating a new file
and saving an
existing file to disk
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Fragmentation and Defragmenting
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How data is physically stored on the
disk
Read/Write Heads = Part of disk drive which skims the
disk (ten millionths of an inch) in order to retrieve or
store information.
Disk Crash or Head Crash = When the R/W head
touches the disk.
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Formatting a disk
Q: Why do we format a disk and
what actually does it?
A: We format a disk so it can be
used by the operating system
software. The operating system
software does the formatting of
the disk.
Q: How does the operating system
do it?
A: There is a operating system
software file (program) which
does the formatting. (CPU/RAM)
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Formatting a disk
What does formatting a disk do?
1. Erases all of the information on the disk
2. Prepares disk to be used by the operating system
software.
• divides tracks into sectors
• determines cluster size
• creates a file allocation table (FAT) or similar table on
other operating systems
3. Optional: Copies operating system files to this disk in
order to make this a “boot disk”
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How Data is Removed from Floppy disks and Hard disks
Who's in charge of deleting files?
Deleting a file:
Unerasing a file
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Recovering Data
•
Norton Utilities™
– Optimizes and
defragments files for
faster hard drive
performance.
– Detects and fixes many
Windows® and disk
problems automatically.
– Can monitor your PC
continuously to spot
problems before they
occur.
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Optical Disks - CD ROMs
Recording bits of data
• Data is permanently recorded by a laser beam on a disk
• WORM = Write Once Read Many
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Pit = On
No Pit (Land) = Off
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Optical Disks - CD ROMs
Advantages of CD ROM over magnetic disks
• capacity and durability
Disadvantage
• WORM
Read Only Drives and Read/Write CD ROM Drives
Capacity
• currently = 650 MB
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Optical Disks - CD ROMs
What are CD ROMs good for?
• graphics, videos, games,
software, (backups)
Speed of CD ROM Drives
• 4x, 6x, 8x, 10x, etc.
• larger the number, faster the
transfer speed from the CD
ROM to RAM
What’s next?
• Need more capacity and faster
speeds.
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http://www.computerhope.com/help/cdrom.htm
• OTHER CD TECHNOLOGIES
• CD-R - (CD Recordable) Drive which you are able to write to once.
Once the drive is written to it cannot be erased.
CD-RW - (CD ReWritable) drive which is a popular alternative to the
CD-R drive. CD-RW has the capability of being written to at least one
thousand times. The drawback with CD-RW diskettes is with the lower
reflectivity of the disc itself can limit the readability. Many CD-ROM and
CD-R drives may have a difficult time reading these disks.
DVD - (Digital Versatile Disc) New standard released in 1995 which
originally was called Digital Video Disc was later changed to Digital
Versatile Disc. DVD offers an initial storage capacity of 4.7GB (of
digital information on a single-sided, single-layer disc the same
diameter and thickness of a current CD-ROM.
DVD-RAM - ReWritable drive type that uses a phase-change
technology like the CD-RW drives. However , DVD-RAM discs cannot
be read by standard DVD-ROM drives because of the differences in
both reflectivity of the medium and the data format.
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http://www.videohelp.com/dvd
•
DVD-R and DVD-RW
– DVD-R was the first DVD recording format released that was compatible with
standalone DVD Players.
– DVD-R is a non-rewriteable format and it is compatible with about 93% of all DVD
Players and most DVD-ROMs.
– DVD-RW is a rewriteable format and it is compatible with about 80% of all DVD
Players and most DVD-ROMs.
– DVD-R and DVD-RW supports single side 4.37 computer GB* DVDs(called DVD-5)
and double sided 8.75 computer GB* DVDs(called DVD-10).
– These formats are supported by DVDForum.
•
DVD+R and DVD+RW
– DVD+R is a non-rewritable format and it is compatible with about 89% of all DVD
Players and most DVD-ROMs.
– DVD+RW is a rewritable format and is compatible with about 79% of all DVD
Players and most DVD-ROMs.
– DVD+R and DVD+RW supports single side 4.37 computer GB* DVDs(called DVD-5)
and double side 8.75 computer GB* DVDs(called DVD-10).
– These formats are supported by the DVD+RW Alliance.
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http://www.videohelp.com/dvd
•
DVD+R DL
– DVD+R DL or called DVD+R9 is a Dual Layer writeable DVD+R. The dual layered
discs can hold 7.95 computer GB* (called DVD-9) and dual layered double sides
15.9* computer GB (called dvd-18).
•
DVD-R DL
– DVD-R DL or called DVD-R9 is a Dual Layer writeable DVD-R. The dual layered
discs can hold 7.95 computer GB* (called DVD-9) and dual layered double sides
15.9* computer GB (called dvd-18).
•
•
DVD-RAM
DVD-RAM has the best recording features but it is not compatible with most DVD-ROM
drives and DVD-Video players. Think more of it as a removable hard disk. DVD-RAM is
usually used in some DVD Recorders.
This format is supported by DVDForum.
•
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What are the features of DVD-Video?
•
•
•
•
•
•
•
•
•
•
•
•
Over 2 hours of high-quality digital video (over 8 on a double-sided, duallayer disc).
Support for widescreen movies and standard or widescreen TVs (4:3 and
16:9 aspect ratios).
Up to 8 tracks of digital audio (for multiple languages), each with up to 8
channels.
Up to 32 subtitle/karaoke tracks.
Multilingual identifying text for title name, album name, song name, actors,
etc.
Automatic "seamless" branching of video (for multiple story lines or ratings
on one disc).
Up to 9 camera angles (different viewpoints can be selected during
playback).
Menus and simple interactive features (for games, quizzes, etc.).
"Instant" rewind and fast forward, including search to title, chapter, track,
and timecode.
Durability (no wear from playing, only from physical damage).
Not susceptible to magnetic fields. Resistant to heat.
Compact size (easy to handle and store, players can be portable).
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Disk Cartridges
Disk Cartridges = portable disks which store almost as
much information and is almost as fast as a hard disk
drive
Uses
• same as floppy or tape
Examples:
Iomega Zip Drive = 100 MB
Iomega Jaz Drive = 1 GB
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Flash Drives
•
•
Capacity
– 64 MB
– 128 MB
– 256 MB
– 512 MB
– 1 GB
– And more
$35 to $175
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Overview of Computer
Hardware
CS 1 Introduction to Computers and Computer
Technology
Rick Graziani
Fall 2006