Transcript ITED 328 Spring 2004

PTTE 428
Fall 2005
Loosely covering chapters 3 & 4
of the text.
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Spring 2004
Announcements:
Lab to do installation of Windows NT
will take place in Room 101 in the
basement level of the CHE Building.
 We are covering Chapters 3 & 4 tonight
 Class Website (it should be working):
http://www.if.uidaho.edu/~nimsrj/
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Back tracking a bit
to chapter 2:
For computers,
always start
counting at zero
Binary numbers
base 2, only 2
values 0 or 1
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Decimal numbers are
base 10
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Octal numbers are
base 8. 0-8
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(HEX) Hexadecimal
numbers are base 16,
0-9, A, B,C,D,E,F
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Powers of 2
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2
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0
1
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=
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1
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8
16
64
128
512
1024
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Bit positions in a
binary number
correspond to the
powers of 2.
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Example Problem:
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1)
100 in base 10 = ? in binary
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100 - 64 = 36
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36 - 32 = 4
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Example Problem:
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2) 10101 in base 2 ( binary) = ? in decimal
Bit position :
16 8 4 2 1
What is really there: 16 + 0 + 4 + 0 + 1
= ?
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MAIN FUNCTIONS of an OPERATING SYSTEM:
Program execution
I/O operation
File System manipulation
Communications
Error Detection
Resource allocation
Accounting
Protection
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SYSTEM CALLS
Process control
 File management
 Device management
 Information maintenance
 Communications
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Fact to remember:
 When a program is running, it is
called a “Process”.
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SYSTEM Programs|
 File management
 Status information
 File modification
 Programming language support
 Program loading and execution
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Most computers these days use a
layered approach to system design.
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Chapter 3 Computer Software
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Software can be divided into several
levels
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The operating system and its associated
system level programs needed to run the
computer ( utilities, printer drivers, boot
files, BIOS, I/O port interface software,
user interface software).
Application programs to perform specific
user needs ( word processors, spread
sheet programs, tax programs, email
programs, simulation programs, games,
custom developed programs).
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Software is made up of files but not
all files are software there are
programs and data files.
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The User interface is the
communication link to the
applications of the computer.
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The application programs relay
information and requests to the
operating system , which in turn will
interact with the hardware.
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Types of operating Systems:
 Stand alone or single user system -One set of I/O and only one user at
a time.
 Multi-user Operating System -- A
system that can have more than one
set of users and I/O at the same
time. A main frame.
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Network Operating System (NOS) A
system that shares resources ( i.e.
printers) or information and
provides communications.
( The school network of computers or
at work).
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Multitasking Operating System - A
system that can run multiple
programs at the same time.
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Embedded Operating Systems – a
self contained operating system that
is dedicated to a specific function.
( Robotics, Air planes, Automobiles.)
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multi threaded:
Sharing a single CPU between multiple
tasks (or "threads") in a way designed to
minimize the time required to switch
threads. This is accomplished by sharing
as much as possible of the program
execution environment between the
different threads so that very little state
needs to be saved and restored when
changing thread.
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Multithreading differs from multitasking in
that threads share more of their
environment with each other than do
tasks under multitasking. Threads may be
distinguished only by the value of their
program counters and stack pointers
while sharing a single address space and
set of global variables. There is thus very
little protection of one thread from
another, in contrast to multitasking.
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Desktop Operating System - The
personal PC. A windows or MAC.
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Common operating systems:
 Various flavors of windows: windows 3.1,
windows 95, windows 98, windows 2000,
windows XP (home and Professional
versions) Windows ME , Windows CE
 A Windows NT or Windows 2000
computer can be configured as a server.
(You need extra software to do this,,
which you have to buy separately)
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Linux flavors: REDHAT, SUSE,
Mandrake,embedded Linux
(Linux is a PC version of Unix)
(If you learn Linux, you have learned
most of UNIX as well)
Linux can be configured to be a server
type computer( the software for this
comes as part of the package).
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Others:
Macintosh
 Be
 Lindows
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System Level Software, the average
everyday use does not see.
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Memory management software
allocates / deallocates sections of
memory used by various programs.
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APPLICATION SOFTWARE
The everyday user can access if they
have permission.
Types of application software:
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Document production :Word processors,
Web publishing.
Spread Sheet software: Excel, Lotus 123
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Database software: access, Oracle,
 DBMS - Data Base Management System
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or Software
Several kinds of DBs : Relational,
Hiearchial ( old) , Object Oriented( Pass
Port uses this).
Only specific data types are allowed.
All use some form of SQL ( Structured
Query Language)
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Presentation software: Power point
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Accounting software
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Games,
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Graphics software
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CAD systems, CASE systems
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Most software that is purchased requires some
sort of license agreement in order to operate,
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Some require keys, either software or hardware,
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There is also "shareware" and "freeware" Open
Source.
"Share ware" is TBD
"Free ware" is TBD
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Freeware is software written by
enthusiasts and distributed at no
charge by users' groups, or via the
World-Wide Web, electronic mail,
bulletin boards, Usenet, or other
electronic media.
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Shareware is software obtained
(downloaded) and redistributed for free,
but most often is under copyright and
does legally require a payment in the
EULA, at least beyond the evaluation
period or for commercial applications.
This payment, as well as fulfilling the
user's legal obligations, may buy
additional support, documentation, or
functionality.
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Several ways to install software: self
installing executables, zip files, the
good old fashioned way - manually ,
(also via disk imaging from a server)
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NOTE: I highly recommend
rebooting after ANY windows
application installation
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REGSITRY: is a database of the
configuration settings used on a
windows operating system
computer. It replaces a lot of the
*.ini files that used to hold the same
information.
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Uninstalling may or may not be a
clean process.
Joke: How may software engineers
does it take to change a light bulb?
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TAKE A BREAK !
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Chapter 4 FILES
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file naming conventions - a good way to
do it
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Most file systems follow some sort of
convention
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A file designation : filename. extension
Depends on limits imposed by the OS.
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A limit to length and type of
characters used in the filename.
 Depends on limits imposed by the
OS.
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The extensions have special meanings: .doc for
document, .exe for executible,
.f for fortran source file, .c for C source file, .bas
for a basic file, .xls for a spreadsheet file,etc.
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A path is the complele file designation for a file.
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One cannot use a reserved word for a file name.
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File management system - how files
are arranged and kept track of, in
some sort of hierarch or tree
structure.
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DO THIS NOW:
Pull up a top level widow, expand a
directory, do a screen dump, print it
out, put your name on it and hand it
in!
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Basic file operations:create, rename,
move, copy, delete.
 (if programming can open and close
them too)
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Security Issues
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Viruses - self replication code that
attaches itself to a file, and spreads via
transfer of the infected file, somewhat
passive
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Worms - A program that spawns copies
of itself in your system, eventually using
up the system resources. Especially
dangerous over a network.
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Trojans - a file that contains legitimate
code and additional code that will use
your computer resources without your
knowledge (email, act as a router, be
used as a storage area).
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Denial of service attack (DOS) - fills up
your hard drive so the computer
eventually halts.
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Good idea to have a personal firewall and
use virus checking software.
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WHY ?
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If your computer is involved in some
illegal activity, you are responsible, even
if you are unaware of the involvement!
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2 kinds of virus checking software
one that scans for specific patterns
and one that looks for heuristics (
recognizes informal rules or
patterns)
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Always good to backup your
computer!
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Why ?
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What could fail?
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Why? Sooner or later you WILL have a
failure.
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What could fail?
Hardware failure like a drive or a
component on the motherboard.
Software failure in the operating system,
or in one of the application programs.
Or you get invaded by a worm / virus or
other attack.
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How to do ?
Over the network if at work.
Use one or more forms of media to
transfer files.
Have media disks to reinstall applications,
os.
suggest keeping a log to track what was
installed, the date, important data.
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Types of backups:
Fullbackup – everything.
 Differential backup - only the files
that changed.
 partial or incremental backup - only
files that were added or changed
since last backup.
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