Transcript Class #2

Intro to Information Systems I
System & Application Software
ISYS 101
Glenn Booker
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System Software
• System software includes the operating
system (OS) and utilities
• The operating system performs the basic
functions for a computer to be a computer
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Communicate between software and hardware
Read from and write to storage
Manage memory
Run applications
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Operating System
• The main part of the operating system is the
kernel, which is always in memory
(“resident”) when the computer’s running
• Other parts of the operating system are
called upon as needed (“non-resident”)
• Operating systems are CPU-specific
– You can’t run Windows on a G4 processor
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Operating System
• DOS was a single tasking operating system
– you could only run one program at a time
• Most OS’s are multitasking – they can run
many programs at once
– One is the foreground application, the others
are background applications
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Multitasking
• Older OS’s (Windows 3.1) used cooperative
multitasking – the foreground application
uses all of the CPU’s attention
• Newer OS’s (MacOS 8-X, Win NT) use
preemptive multitasking, which isolates
each application in memory
– Even if an application crashes, the operating
system doesn’t
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Multithreading, Multiprocessing
• Within one application, multithreading
allows several tasks (“threads”) to be done
at the same time
– Most modern OS’s use multithreading
• Multiprocessing (MP) is when the computer
has more than one CPU
– For symmetric MP, each thread can be assigned
to a different CPU
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Memory Management
• Memory (RAM) is divided into partitions
for each application
• If RAM is limited, part of the hard drive can
become virtual memory
• Chunks of memory are divided into “pages”
to pass in and out of virtual memory
• Pages are written in a swap file on hard disk
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Interfaces
• Hardware interfaces are controlled by
programs called device drivers
– Most are installed automatically
• User interfaces are
– Command line (DOS, UNIX)
– Menu-driven (CMOS – see later)
– Graphical user interface (MacOS, Windows)
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User Interface
• The user interface lets the user
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Gain access to the computer (log in)
Run applications
Manage disks and files
Shut down the computer safely (necessary
since DOS)
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Types of Operating Systems
• UNIX is a 30+ year old family of operating
systems
• Mostly used for servers and workstations
• Dependable and very powerful, but hard to
learn and somewhat obtuse (rename = mv)
• Two major subfamilies: IBM System V and
Berkeley BSD
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Major UNIX Brands
IBM
AIX
Sun
Solaris,
SunOS
Apple
MacOS X
SGI
Irix
HP
HP/UX
DEC/
Compaq
Tru64
UNIX
On Intel-based computers, SCO and BSD are also available.
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Types of Operating Systems
• MS-DOS powered the IBM PC in 1981, and is
still partially the basis for Windows ME
– Command line interface
– Copied by PC-DOS, DR-DOS
– 640 kB RAM limit originally
• While Xerox invented the GUI in the late 70’s,
Apple capitalized on it with the Macintosh,
now running MacOS 9 or X
– 32-bit System 7 released in 1991
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Types of Operating Systems
• Microsoft Windows
– Windows 3.x added GUI on top of DOS,
but treated CPU as though it were 16-bit
– Windows 95, 98, and ME are all still
DOS-based, but try hard to be 32-bit
operating systems
– Windows NT and 2000 are clean 32-bit
OS’s, which emulate DOS if needed
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Types of Operating Systems
• Windows CE (WinCE?) is used for small
portable devices (palmtops) (Windows lite)
• Linux is a clone of UNIX, developed
starting in 1991 by Linus Torvalds
– A third of Web servers run Linux
– New GUI’s (Gnome and KDE) help reach
desktop market
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Types of Operating Systems
• Mainframe or minicomputer operating
systems include Unix and:
– IBM’s OS/390 for S/390 computers
– IBM’s OS/400 for AS/400’s
– Compaq’s VMS for VAX/VMS or
OpenVMS-based computers
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Types of Operating Systems
• Windows XP (“Whistler”) will be first
Windows operating system for home and
office which is 32-bit clean
– It’s about time!
– A special 64-bit version will be made for
Itanium
• BeOS (www.be.com) is a free OS for
graphic and multimedia applications
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Computer Startup
• Starting a computer is “booting” it
– From turned off, it’s a “cold boot”
– From already running, it’s a “warm boot”
• First see the BIOS (Basic Input/Output
System) screen
– BIOS controls what the computer boots from
(floppy, hard drive, CD) and helps initially
configure the hard drives
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Computer Startup
• After the BIOS is happy, the Power On Self
Test (POST) makes sure the hardware is
attached
– Checks RAM, hard drive, floppy, keyboard,
and mouse
• Then the OS loads into RAM
• Then you can log in
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Profiles
• If your OS supports multiple logins, then
when you log in you get:
– Unique desktop appearance as defined in your
user profile
– A home directory for your files
– Varying privileges for running applications
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Utilities: File Management
• Basic file management utilities (like
Windows Explorer) help organize files
• Files under Windows have a file name
(myfile), a period, and extension (doc)
– The extension is used to associate files with the
application used to open them
• Files are kept in directories (folders)
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Utilities: Backup
• Backup utilities help archive the contents of
your hard drive(s) in case of disaster or
severe corruption of the disk
• Full backup copies everything in the disk
(or specified folders)
• Incremental backup copies only those files
which changed since the last backup
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Utilities: File Compression
• File compression utilities squash files and
directories to make backup or transfer (e.g.
via floppy or email) easier
• WinZip and StuffIt are the most common
• Pkzip was an early DOS/Windows version
• Text files and bitmaps compress the best;
some formats are already compressed (JPG)
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Utilities: Disk Scanning & Defragmenting
• Some utilities help manage the physical
hard drives, including defragmenting
• They also scan, erase, and format drives
– Windows has built-in “scandisk” & defrag tools
– DiskKeeper is used for Windows NT or 2000
– FWB Hard Disk Toolkit for Mac
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Application Software
• Application software is broken into
horizontal and vertical apps
– Horizontal apps are widely used across many
types of work (Word, Excel, etc.)
– Vertical apps are designed to manage one entire
business function (e.g. manufacturing)
• Custom software is needed if one of the
above doesn’t meet your needs ($$$$)
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Application Software Types
• Three major categories of horizontal apps
used for business
– Personal productivity (Office)
– Multimedia & graphics (Photoshop, Fireworks,
Paint Shop Pro, PageMaker, Quark)
– Internet (Outlook, FrontPage, Internet Explorer,
Netscape)
– Plus personal finance & tax software for home
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Software Requirements
• The required hardware and software for
running an application typically includes
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Type of CPU
Type of operating system
Amount of RAM
Amount of hard drive space free
Other special needs (mouse, CD-ROM, etc.)
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Software Licensing
• Commercial software is often charged per
copy of the software, or per CPU
• Shareware is free, but you should send in
money if you use it a lot
• Freeware is free
• Some software is public domain
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Software Licensing
• Linux falls under the GNU Public License
(GPL)
• Some demos or beta versions are time or
feature-limited
• Academic software might have time or
feature limits
• Site licenses help manage large facilities
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Software Distribution
• Software may be distributed on CD-ROM
or downloaded via the Internet
• Documentation may be electronic (PDF)
and/or paper
• Versions (3.0) indicate a major revision;
• Maintenance releases (3.1) indicate minor
improvements and fixes
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Software Installation
• Software is installed using a special
program for that purpose
• Installers uncompress files, and copy them
to your hard drive
• Windows apps add entries in the Registry,
and in the Control Panel called
Add/Remove Programs
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Software Installation
• Registration of the software is expected
immediately after installation
• Some apps come with uninstall programs,
too – otherwise use Add/Remove Programs
to delete them (please!)
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Visual Metaphors
• Good software is based on familiar visual
appearances
– Word processing looks like a letter
– Spreadsheet looks like that used by an
accountant
– Databases look like file cards
– Contact managers look like an address book
– Personal finance program looks like checkbook
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Integrated Applications
• Often applications from a single vendor are
integrated to work more closely with each
other
– MS Office, Works
– Lotus SmartSuite, Corel Office
• On a larger scale, this leads to vertical
applications (e.g. SAP)
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Windows Environment
• A typical window has:
• Title bar at the top, with minimize,
maximize, and close window controls on
the right of the title bar
• Then a Menu bar (File, Edit, …)
• Then one or more Toolbars
• Your work is in the Application workspace
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Windows Environment
• The right side of the window has the scroll
bars, arrows, and boxes
• Under the workspace is the status bar
(which tells you when you’re printing, etc.)
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Word Processing
• Word processing allows composition of
letters, reports, and other major documents
with few formatting needs
– If you need complex formatting, use a desktop
publishing program instead
• Basic word processing allows for creating,
editing, formatting, and printing a document
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Word Processing
• One document might be broken into
Sections
– Each section can have its own margins,
orientation (landscape vs portrait), page
numbering, headers and footers
• Within a section, the paragraph is the next
major element
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Word Processing
– Each paragraph may have styles associated with
it, as well as line spacing, indenting, and
spacing before and after the paragraph
• Below the paragraph, the character is the
next unit
– Each character may have a font size, style,
color, and other effects (shimmer, etc.)
– Symbols and images are characters
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Word Processing
• Word processing programs can add other
features, like:
– Footnotes and endnotes, page numbers, tables
of contents, indexes, etc.
– Tracking changes for document review
• Beware of grammar and spelling checkers!
– Many errors won’t be caught be them
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Spreadsheets
• Spreadsheets mimic an account’s
spreadsheet – used to add rows and columns
of numbers
• Now they also do charts and help
analyze data
• Data are in columns (for each type of data)
and rows (for each record or transaction)
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Spreadsheets
• Excel limited to 256 columns and 65,536
(64k) rows
• One spreadsheet document can have many
“sheets” (up to available memory)
• Spreadsheets calculate based on cell name
references
= A1 + B3*C3
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Spreadsheets
• Spreadsheets recognize three types of data
– Numbers (including percent, integers, real
numbers)
– Dates and/or times
– Text (“Hi this is a text cell”)
• Fill handles or autofill help enter patterns of
data quickly
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Spreadsheets
• Fixed, or absolute cell references can be
defined
= $A$1 + B3*C3 (fixes A1)
• Math functions can be used (beware of
weak statistical functions)
= SUM(B1:G1)
• Formatting of fonts, rows, columns, page
breaks, etc. can be done too
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Spreadsheets
• Most charts can be generated using the
Chart Wizard
– Also can embed Excel objects, including data
and charts, in a Word document
• Macros can be used for more complex
programming in Excel
• Be sure to check sample calculations!
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Presentations
• Presentation graphics (PowerPoint) are
generally for less technical work than
analytical graphics (Excel or SPSS)
• Images are based on vu-graph slides
• Slides can be viewed together (slide sorter),
or view an outline of the presentation
• The Notes view reminds you what to say
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Presentations
• A master slide can contain common
elements you want in the background for
every slide (logos, copyright data,
presentation or presenter name, etc.)
• Now presentations can have headers and
footers too, like Word documents
This stuff is in the footer!
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Presentations
• Templates can provide a set of predefined
layouts and fonts, but generally do so at the
expense of contrast (use a good projector!)
• Entire presentations are outlined in the
AutoContent Wizard (under File / New)
• Animation and movement can also be used
• But sometimes badly
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Presentations
• Sound, video, and Internet content are
possible
• Keep the content focused on each slide
• Some recommend no more than five lines,
with 5 words per line (the 5x5 rule)
• Fonts generally shouldn’t go below 24 point
• This is 32 point Times, with 44 point titles
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Databases
• Databases are used for storing, sorting, and
analyzing lots of data
• Data is stored in tables
• Forms are used for displaying and entering
data
• Reports are used for output of data
• Queries are used to select data from tables
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Database Tables
• Tables have records; records are like rows
in Excel
• Each record (customer) has one or more
fields in it (name, address, zip code); fields
are like columns in Excel
• Each field has a data type (text, number
(integer or real), money, date, T/F, etc.)
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Databases
• Each table is one type of information which
can be associated with one unique identifier
– A person has a SSN
– A purchase order has a PO number
• That unique identifier is the “primary key”
• One event (a purchase) may involve data
from several different tables
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Databases
• For example, one customer may have
placed many orders
• A single order may have many items in it
• But a customer might have only one
shipping address
• Those one-to-many and one-to-one
relationships make a relational database
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Databases
• The use of relational data prevents
duplication of data, and allows analysis in
many ways otherwise not possible
• Reports can be generated which draw from
many tables
• Forms may accept input which goes into
several tables
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Databases
• Queries draw from many tables to find, for
example, a particular type of data, e.g.
– Find all of the customers in the Delaware valley
– Determine the total sales for each sales person
last month
– Which suppliers have been most reliable?
– When do we need to reorder tuna fish?
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Other Database Considerations
• Validation: databases can check their inputs
and outputs to make sure they are the
correct format and range
• Data integrity refers to data being a correct
possible value (gender = M or F, not Q)
• Database independence refers to the ability
to keep the data when the database program
needs to be updated or replaced
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Other Database Considerations
• Data should be kept in only one place (no
redundancy)
• Data needs to be secure, so that only those
who need to get to it may do so
• Maintenance issues need to be addressed,
such as adding or deleting data or users of
the database
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Other Database Considerations
• Large scale databases need to consider the
need for replication, where several copies of
data are maintained in different servers
– Local replication is also done (e.g. sales staff
maintaining a replica of product features and
costs)
• The location where computation is done
may be distributed to different servers
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Other Database Types
• A flat file database is like using multiple
spreadsheets (FileMaker Pro, or COBOL)
• Object-oriented databases exist; some are
cross-bred with relational databases to make
object-relational databases
• Groups of databases can form warehouses
or data marts, and support data mining
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Database Architecture
• Databases can be client/server architecture
(users run a client program, which asks the
server for data as needed)
• Or many databases are becoming web-based
(typically using CGI, ASP (Microsoft), or
JSP (Sun) programs to query the database)
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