Transcript Input, Process, Output - Washtenaw Community College

Session 2:
Computing
Components
Nell Dale • John Lewis
Session Goals
Begin to understand the jargon used in
computing
List the components and their function
in a von Neumann machine
Describe the fetch-decode-execute cycle
of the von Neumann machine
Session Goals (cont.)
Describe how computer memory is
organized and accessed
Name and describe different auxiliary
storage devices
Define parallel computer configurations
Computing as a Tool
Programmer / User
Systems Programmer
(builds tools)
Applications Programmer
(uses tools)
Domain-Specific Programs
User with No
Computer Background
20
Computing as a Discipline
Four Necessary Skills
1. Algorithmic Thinking
2. Representation
3. Programming
4. Design
21
Computer Components
Consider the following ad
Sizes in Perspective
Admiral Grace Murray Hopper

A coil of wire nearly 1,000 feet long
 Distance traveled by an electron along the wire
in the space of a microsecond

A short piece of wire
 In the space of a nanosecond

A bag containing grains of pepper
 In the space of a picosecond
Sizes in Perspective
Stored-Program Concept
Figure 5.1 The von Neumann architecture
System Components
Hardware

I/O devices (input/output)
 keyboard, mouse, monitor, etc.



CPU
Primary Storage
Secondary Storage
Software
Typical System
Computer case
Monitor
Printer
Speakers
Modem
Keyboard
Mouse
Computer Components
Power supply
Hard drive
Expansion card
Expansion slot
System board
CD-ROM or DVD-ROM
Floppy disk
Drive bay
Central Processing Unit (CPU)
Random access memory (RAM)
Processing
The Fetch-Execute Cycle
Fetch the next instruction
Decode the instruction
Get data if needed
Execute the instruction
The Fetch-Execute Cycle
Sample Processing Sequence
Two numbers in main memory are added
Instruction is transferred from memory into the CPU
Location of the instruction being processed is updated
in the instruction counter (IC) or program counter
(PC)
3. The instruction just fetched is stored in the
instruction register (IR)
4. CU decodes the instruction to add two numbers
1.
2.
•
•
5.
6.
7.
8.
9.
operator [operand1], [operand2], [operand3]
ADDW3 first_no, second_no, answer
•
W = words, 3 = no of operands in the instruction
Numbers are located in main memory
Fetched into internal registers of the ALU by the CU
Addition is carried out by ALU
Sum stored in new memory location by CU
The IC is updated to point to the next instruction
Memory
Memory is a
collection of
cells,
each with a
unique physical
address
Computer Architecture
Microprocessor (examples Pentium, Pentium
II, PowerPC, etc.)

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includes Bus Interface Unit, Arithmetic & Logic
Unit (ALU), Control Unit, registers
motherboard is simply the main circuit board that
contains most of these parts
the CPU (central processing unit) is considered to
be most of these parts taken as a whole
Bus


connects the microprocessor to the RAM & ROM
addresses for data and instructions are important
CPU (Central Processing Unit)
Processes instructions, performs calculations, and
manages the flow of information
Performance:

CPU speed is a major factor in determining how fast a
computer operates (faster the speed, faster computer
operates)
 Measured in gigahertz (GHz) A clock cycle relates to the clock
that controls the timing in the microprocessor.
 For example, a 1.4GHz (gigahertz) clocked microprocessor
generates 1.4 billion clock cycles per second.

Each generation of CPU is more powerful than the one
before. It's clock cycles are faster at a given speed
Processing
The Central Processing Unit (CPU) is the
main chip in a computer



Processes instructions
Performs calculations
Manages the flow of information
Types of CPUs (Chips)
Intel Pentium Processor
Intel Celeron

Needs of home machines
AMD Athlon Processor

Business and home use
AMD Duron Processor

Home use
VIA Cyrix Processor

Inexpensive CPU
Main Memory / Primary Storage
Speeds up computer by storing data the
computer has recently used


Internal Cache: On CPU chip (L1 or primary cache
External Cache: On the system board and consists
of Static RAM (SRAM chips)
 Sometimes built into chip
RAM – slower main memory

Each time the computer requests data from RAM,
the computer places a copy of the data in memory
cache
 Constantly contains the most recently used data
Storage Devices
Primary storage

RAM (Random Access Memory, or just “memory”
for short)
 active data that is being stored, lost if power is cut off so
save often

ROM (Read-Only Memory)
 commands that are permanently stored on chips
 PC’s use BIOS, Macs use the Toolbox
Secondary storage


Hard disk, floppy disks
Slower method of storage & retrieval but “safer”
Random Access Memory
Random Access Memory – Temporarily
stores data inside a computer


Constantly overwritten
Measured in megabytes (MB)
If you have limited memory or you have
many programs open, your computer may
need to use part of the hard drive to
simulate more memory
RAM and ROM
RAM stands for Random Access Memory

Inherent in the idea of being able to access each
location is the ability to change the contents of
each location
ROM stands for Read Only Memory

The contents in locations in ROM cannot be
changed
RAM is volatile, ROM is not

This means that RAM does not retain its bit
configuration when the power is turned off,
but ROM does
Using Memory
1. Look through documents on your desk
(internal cache)
2. Look through documents in your desk
drawer (external cache)
3. Looking through documents in your
filing cabinet (RAM)
4. Go out and get it from the trunk of
your car (secondary storage)
Control Unit
Control unit is the organizing force
in the computer
There are two registers in the control unit


The instruction register (IR) contains the
instruction that is being executed
The program counter (PC) contains the address
of the next instruction to be executed
ALU and the control unit called the Central
Processing Unit, or CPU
Arithmetic/Logic Unit
Performing basic arithmetic operations
such as adding
Performing logical operations such as
AND, OR, and NOT
Most modern ALUs have a small amount
of special storage units called registers
Input/Output Units
An input unit is a device through which data
and programs from the outside world are
entered into the computer

Keyboard, the mouse, and scanning devices
An output unit is a device through which
results stored in the computer memory are
made available to the outside world

Printers and video display terminals
Math Coprocessors
A special processing unit that assists
the CPU in performing certain
operations.

A math coprocessor is a chip or part of a
chip that specializes in doing math.
Hardware that attaches to the
motherboard or is part of the CPU.
Also called numeric coprocessors
or floating point units (FPU).
Flow of Information
The parts are connected to one another
by a collection of wires called a bus
Figure 5.2 Data flow through a von Neumann architecture
Bus
Electronic pathway that carries
information between devices in a
computer

Bus Width (think lanes of a highway)
 8 bits is one character

Bus Speed (think speed limit)
 Measured in MHz (millions of cycles per
second)
Parallel Processing
Synchronous processing
One approach to parallelism is to have multiple processors apply
the same program to multiple data sets
Figure 5.6 Processors in a synchronous computing environment
Pipelining
Arranges processors in tandem, where
each processor contributes one part to
an overall computation
Figure 5.7 Processors in a pipeline
Peripherals
Ports
Ports are connectors at the back of a
computer system that you use to plug
in an external device. This allow
instructions and data to flow between
the computer and the device
Any Port in a Storm
Parallel port – 25 holes; female connector; LPT1;
printer or storage devices
Monitor port
Keyboard port
Serial port – 9 or 25 pins; male connector; COM1;
mouse or modem
Game port
Network port
USB port

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127 devices
Printer, modem, joy stick
Firewire
USB and Firewire
High-speed ports that allow information to
quickly transfer between a computer and an
external device

USB
 Supports up to 127 device

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USB 1.0: 12 megabits per second
USB 2.0: 480 Mbps
FIREWIRE
 63 devices at 400 Mbps
 Can purchase Firewire expansion card
Storage Devices
Secondary Storage Devices
Because most of main memory is volatile and
limited, it is essential that there be other
types of storage devices where programs and
data can be stored when they are no longer
being processed
Secondary storage devices can be installed
within the computer box at the factory or
added later as needed
Magnetic Disks
A read/write head travels across a spinning
magnetic disk, retrieving or recording data
Figure 5.5
The organization
of a magnetic disk
Hard Drives
Magnetically stores data on rotating
disks called platters
Capacity is measured in bytes
Speed is measured in revolutions per
minute
Floppy Drives and Drives
Removable media


Can be write-protected
Can be damaged magnetically
Magnetic Tape
The first truly
mass auxiliary
storage device
was the magnetic
tape drive
Figure 5.4 A magnetic tape
Tape Drive
Backup helps you copy files to tape
cartridges
Try to find a drive that can store the
entire contents of your hard drive
Removable Storage Devices
Jazz Drive – 2 GB
Zip Drive – 250 MB
LS-120 Drive – 120 MB
Compact Disks
A CD drive uses a laser to read
information stored optically on a plastic
disk
CD-ROM is Read-Only Memory
DVD stands for Digital Versatile Disk
CD-ROM
ROM (Read-only memory) - can’t be changed
650 Mb of data

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Equal to entire set of encyclopedias
400 Floppy disks
Speed determines how fast a disk spins

Look for 48X
Speed of CD-ROM drive is the transfer rate

In Kb (e.g. 3600Kbs)
CD-R & CD-RW Drives
CD-R (Compact Disc – Recordable)

Permanent store; not erasable
CD-RW

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Can be erased and rewritten
Read / Write and Re-write speeds
Usually 74 minutes
Special software needed to record onto a disk

Referred to as burning a CD
DVD-ROM Drive
DVD – Digital Versatile Disk

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Generally cannot change the information stored on
a disk
Similar to CD but stores more information
Speed determines transfer rate (6 X)
Capacity
 1 side / 1 layer – 4.7 GB
 1 side / 2 layer – 8.5 GB
 2 sides / 1 layer – 9.4 GB
 2 sides / 2 layers – 17 GB
Input and Output
Input Devices
Keyboards
Mice


Trackballs
Pointing Devices
Scanners
A scanner is a device that reads
images and text into a computer


Optical Character Recognition (OCR)
software that places scanned text
into a document that can be edited
in a word processor
Color depth is measured in bits and
indicates the number of colors a
scanner can detect
Resolution
Resolution determines the amount of
detail a scanner can detect
 Ranges from 600 dpi to 2400 dpi
 You usually don’t need to scan at a higher
resolution than a printer can produce or a
monitor can display


Most monitors are 72 dpi
Printers vary
Output Devices
Printers
Speed of a printer is measured in pages per
minute (PPM). A higher speed represents
faster output
Resolution determines the quality of images


A higher resolution results in sharper images
Printer resolution is measured in dots per inch
(dpi)
 600 dpi is acceptable; 1200 is better for images

Resolution expressed with two numbers
represents dots per inch across and down
Types of Printers
Ink-jet: has a print head that sprays
ink through tiny nozzles onto a page
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2 to 10 pages (ppm)
360 to 2400 dots per inch
Color printers spray cyan, magenta,
yellow and black to create different colors
Laser-printer
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Works like a photo copier
Speed of 4 to 16 pages
Have a CPU
600 to 2400
Memory – 2mb to 8 Mb
Print Buffer and Spoolers
Printer buffer: section of memory
printer stores information waiting to
print
Printer spooler: program on your
computer that stores information
waiting to print


Stores more information than the buffer
One spooler for each connected printer
Monitors
Video cards translate instructions
from the computer into a form Most
computes the monitor can
understand

require at least 2 mb of video card
memory
Monitor Metrics
The smaller the dot pitch, the crisper
the image

0.28mm is acceptable
Refresh rate is measured in hertz (Hz)
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Times per second computer redraws the
image
72 Hz or more is acceptable
Communications
Modems let a computer exchange
information through telephone lines
Speed of a modem determines how
fast it sends and receives messages

56,000 bps (56 Kbps)
 V.90 standard: receive 56K and send 33.6K

Speed at which information flows depend
on the quality of the phone line
High-speed Connections
ISDN – Integrated Services Digital
Network
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Digital phone line
56 Kbps to 128 Kbps
Cable Modem
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Same cable as TV
4000 Kbps
DSL – Digital subscriber line

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High speed digital phone line
1000 – 6000 Kbps
Operating Systems
Operating Systems
Software that controls the overall activity of
the computer

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Ensure that all of the parts of the computer work
together smoothly
Functions:
 Control hardware
 Run software
 Manage information

Programs that run on one operating system
platform do not generally run on others
Software: Systems Software
Operating systems


Controls the hardware components (disks,
CPU, printers, etc.)
Windows XP, Windows NT/2000, Windows
9-X, MS-DOS, OS/2, MacOS, Unix, Linux,
BeOS
Types of Operating Systems
MS-DOS
 Command driven
Windows
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Windows
Windows
Windows
Windows
Windows
Windows
UNIX
MAC OS
3.1
9X (95, 98)
ME
XP
NT
2000
Unix
Can run single computer or entire
network
Developed on mainframes in late ’60’s
True multi-tasking OS
Most widely used operating system on
Internet
LINUX
Unix-based system offered as freeware
on the Internet
Software
Software
System software runs the machine
Application software helps you
accomplish specific tasks
Manufacturers also may create
minor software updates called
patches, to make corrections or
improvements to software
Utility Programs
Utility: A program that performs a specific
task on your computer
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Norton utilities: recover files
Virusscan: anti-virus software
Acrobat Reader: View PDF (Portable Document
Format) files
Winfax pro
ViaVoice – Speech recognition
WinZip – Compress and decompress files
Application Software:
Word processor
Spreadsheets
Presentation Software
Database Software
Internet Software
Software: Application Software
Office products
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Word processors
Spread sheets
Presentation software
Email
Business applications
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General ledger
Financials
 Accounts payable
 Accounts receivable
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HRMS
Fixed assets/inventory
Database Programs
Helps you manage large collections of
related information
Uses
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Store information
Find information
Analyze and print information
Databases
Organized in:

Tables
 Collection of information about a specific topic

Field
 Category of information

Record
 Single instance of information
Programming Software
Text Editor

Used by the programmer while coding the
program in a programming language
 Like a word processor - creates a text file
containing the program's instructions or "source
code"


Examples are “nled” and “vi” editors in Unix systems
Other editors are NotePad and WordPad which are
text-based
Programming Software
Interpreters

Translates source code into machine code line by
line
Compiler

Translates source code into an object file, than
uses linker to create an executable file
 A source module (source code) becomes an "object"
module (compiled module)
 Then it is linked with system modules to become a "load"
module (linked module)
It is usually more efficient to use a compiler