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Unit 2: Evolution & Architecture
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Unit 2: Reading & Assignments
APA Format
Chapter 1: Computer System Hardware
Chapter 2: Operating System Overview
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Architecture
Evolution of Operating Systems
Microsoft Windows
Unix & BSD
Linux
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Textbook Reading
◦ Chapter 1
 The Memory Hierarchy
 I/O Communication Techniques
◦ Chapter 2
 The Evolution of Operating Systems
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2 Discussion Questions
Written Essay (due Tuesday, November 1)
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Read the article on DMA (Direct Memory
Access). DMA is a common feature in
today's computing technology. Explain the
communication process of DMA and what
devices may potentially use it.
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Write a four-page essay, in APA format, on the evolution of
operating systems.
Your paper should address the different types of operating
systems.
It should focus mainly on Windows and Linux, should address
I/O communication techniques focusing on interrupts and
DMA and should briefly describe memory hierarchy.
In addition please provide a summation of which operating
system you believe could apply to your current business
needs.
PS: the OS you are researching and explaining is to be used
for heavy database functions.
No Abstract or Table of Contents Required
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Paper length is 4 pages and demonstrates student
understands the subjects examined (5 points)
Address OS Evolution as it relates to: Serial
processing, multitasking, time-sharing systems,
interrupts, scheduling and resource management,
and the concept of process (15 points)
Analyzed I/0 Communication Techniques:
Interrupts and DMA (15 points)
Summarized Memory Hierarchy (15 points)
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All assignments must have:
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Title Page
1 inch margins (top, bottom, sides)
Double spaced content
References page (if cited or used for paper)
Meet minimum page counts (not including title, TOC or
refs)
Font – 12 point, Times Roman or Arial
Headings to separate the sections
Use spelling and grammar check BEFORE submitting
paper.
NO need for abstracts in these papers
Table of Contents (for final project only)
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Quote any direct word for word citations (and include
page numbers).
Any direct quotes NOT properly cited is considered
plagiarism by Kaplan University & will be reported!
(Read about plagiarism in “Academic Success”)
3 strikes and you are out…
◦ One Warning – Rewrite paper or receive zero
◦ Strike 1 – Zero on Paper
◦ Strike 2 – Fail Class
◦ Strike 3 – Expulsion from the University
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Used in body of the paper to direct the readers to specific
sources on the reference page.
Placed at the end of the information which came from that
particular source.
Do not use a full web address as your citation!
For summary and paraphrase citations in APA, an in-text
citation is generally the last name of the author and the
year of publication (Fudge, 2007).
For quote citations, you also need to include the page or
paragraph number: for example, (Smith, 2007, p. 32) or
(Jones, 2005, para. 2).
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Reference Page is last page(s) of document.
List of sources you used in preparation of the paper
Allows the readers of your paper the ability to look
up the information you provided
Generally, you need to look for an author, the title on
the top of the webpage or article, the providing
company, a date, and a little more.
If it is a website, you must also provide the date you
looked at it.
A web address by itself is never enough!
Book – one author
Calfee, R. C., & Valencia, R. R. (1991). APA guide to
preparing manuscripts for journal publication.
Washington, DC: American Psychological Association.
Author’s last name, First name initial, Middle initial if
available (Year of Publication). Book title: Subtitle
also starts with a capital letter (edition, if applicable).
City of publication: Publisher (year of publication),
pages.
Article From an Online Periodical
Bernstein, M. (2002). 10 tips on writing the living Web.
A List Apart: For People Who Make Websites, 149.
Retrieved from http://www.alistapart.com/
articles/writeliving
Author, A. A., & Author, B. B. (Date of publication).
Title of article. Title of Online Periodical, volume
number(issue number if available). Retrieved from
http://www.someaddress.com/full/url/
Web Page
Angeli, E. & Brizee, A. (2010, May 5). General format.
Retrieved from http://owl.english.purdue.edu/owl
Author, A. A., & Author, B. B. (Date of publication).
Title of document. Retrieved from http://Web
address
Source:
http://owl.english.purdue.edu/owl/resource/560/01
Computer System
Overview
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Question:
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Why do we need to understand computer
system hardware?
What does an “operating system” have to do
with hardware inside the machine?
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4 structural elements of a computer
◦ Processor
 Controls the operation of the computer and
performs its data processing functions (CPU)
◦ Main Memory
 Stores data and programs & is volatile
◦ I/O Modules
 Move data between the computer & external
environment
◦ System Bus
 Provides communication among processors, main
memory and I/O modules
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Processor has set of registers with memory
faster than main memory
Processor registers functions:
◦ User-Visible registers
Location where variables are assigned & held
◦ Control & Status registers
Controls operation of processor
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Processor fetches instructions from memory
(one at a time) and executes each instruction.
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Volatile memory is erased when computer is
shut down
Different than disk memory that saved
information even after computer is shut
down
Three characteristics of memory:
◦ Faster access time, greater cost per bit
◦ Greater capacity, smaller cost per bit
◦ Greater capacity, slower access speed
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I/O stands for Input/Output Modules
Modules move data from computer to
external environment (disks,
communications equipment & terminals)
3 Techniques for I/0 Operations (pp. 33-36)
◦ Programmed I/O
◦ Interrupt-driven I/0
◦ Direct Memory Access (DMA) ** DQ1
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“The I/O module performs the requested
action and then sets the appropriate bits in
the I/O status register, but takes no further
action to alert the processor” (Stallings, 2009,
p. 33)
The processor must “periodically check the
status of the I/O module until it find that the
operation is complete” (Stallings, 2009, p.
33).
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Processor issues an I/O command and then
does something else.
I/O Module interrupts the processor to
request service when it is ready.
Why is this type of I/O more effective?
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DMA = Direct Memory Access
Performed by separate module on bus or can
be incorporate into I/O module
How is DMA different from interrupt-drive
I/O?
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Set of wires that carries
signals from one
component to another
Provides
communication among
processors, main
memory, and I/O
modules.
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Operating Systems
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Questions
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How would you define “operating system”?
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Why do we need one?
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What is your current operating system on
your computer?
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Textbook definition (p. 51)
“An OS is a program that controls the
execution of application programs and acts
as an interface between applications and
the computer hardware”
Objectives of OS
◦ Convenience
◦ Efficiency
◦ Ability to Evolve
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Program Development
◦ Utility programs supplied with OS such as
debuggers and editors
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Program Execution
◦ Steps performed to execute a program
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Access to I/O Devices
◦ Each I/O device has it own instructions
◦ OS provides uniform interface to connect to devices
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Controlled Access to Files
◦ OS understands nature of I/O device (tape drive, CD
drive, disk drive)
◦ OS understands the structure of the data
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System Access
◦ Controls access to system as whole
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Error Detection & Response
Accounting (usage statistics)
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OS functions in same way as computer
software
OS often gives up control and depends on
processor to allow it to regain control.
Kernel
◦ Contains most frequently used functions in OS
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Why does an operating system
need to evolve?
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Hardware upgrades
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New types of hardware
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New services
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Bug fixes
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Serial Processing
◦ Users have to schedule computer time
◦ Jobs took time to setup (punch cards, load tapes)
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Simple Batch Systems
◦ User submits program to monitor
◦ Monitor schedules program and return results to
user
◦ Example languages: FORTRAIN
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1940s – 1950s Computers
◦ No Operating System
◦ Programmers interacted directly with hardware
◦ Computer ran by display lights, toggle switches,
input device & printer
◦ Serial Processing
◦ 2 Main Problems
 Scheduling
 Setup Time
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1960s Computer
◦ Simple Batch Processing
◦ IBM, GM
◦ User submits jobs on punch cards or tape to a
computer operator
◦ Computer operator “batches” jobs sequentially
◦ Batch is placed on monitor (input device)
◦ When done, program branches back to monitor and
next job is started.
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http://www.nasaimages.org/luna/servlet/detail/nas
aNAS~5~5~22813~127165:IBM-Electronic-DataProcessing-Mach
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Multiprogrammed Batch Systems
◦ Simple batch systems
 I/O devices were slow compared to processor
◦ Needed a way to allow computers to multitask to
eliminate inefficiency
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Time-Sharing Systems
◦ Processor time is used by multiple users
◦ Terminals and central computer
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5 major theoretical advances to make modern
Operating System
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Processes
Memory Management
Information Protection & Security
Scheduling & Resource Management
System Structure
We will cover these 5 topics from Weeks 4-9.
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Latest OS design features
◦ Microkernal architecture
 Only essential features assigned to kernel such as
address spaces, interprocess communications, & basic
scheduling
◦ Multithreading
 Process executing an application is divided into threads
that can run concurrently
◦ Symmetric multiprocessing
 Computer hardware architecture improvement
◦ Distributing operating systems
◦ Object-oriented code
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Microsoft Windows
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Traditional UNIX Systems
◦ From DOS 1.0 (August 1981) to Windows 7
(2009)
◦ Developed by Bell Labs in 1970
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Modern UNIX Systems
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Linux
◦ System V Release 4 (SVR4)
◦ Berkeley Software Distribution (BSD)
◦ Sun Solaris 10
◦ Started as UNIX variant by Linus Torvalds in 1991
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Complete timeline of DOS & Windows at
http://bravotech.us/info/msos-timeline.htm
Features
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Single-User Multitasking (starting with Windows 2000)
Architecture Diagram (Textbook – p. 83)
Modular architecture
Kernel-mode components
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Executive
Kernel
Hardware Abstraction Layer
Device Drivers
Windowing & graphics system
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Started at Bell Labs in 1970
Rewrote UNIX in programming language C
Disadvantages
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Runs on single processor
Lacks ability to protect data
Kernel not designed to be extensible
Few facilities for code reuse
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Modern UNIX Kernel
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Exec switch
Vnode/vfs interface
Scheduler framework
Streams
Block device switch
Virtual Memory Framework
BSD
◦ FreeBSD
◦ Mac OS X based on FreeBSD 5.0 & Mach 3.0
microkernel
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Started in 1991 as a UNIX variant
Created by Linus Torvalds
Features
◦ Open source (i.e., “free”)
◦ Monolithic kernel
◦ Structured as a collection of modules that can be
loaded on demand
 Modules can be linked
 Modules can be stacked
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Comparison chart of Windows vs Linux (p. 95)
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http://distrowatch.com/dwres.php?resource=major
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Pam Van Hook
◦ Email:
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[email protected]
Office Hours:
 Thursday
 Sunday
 via AIM:
7-8 pm ET
10–11 pm ET
[email protected]
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