Introduction to CS/IT Instructor: Yong-nian Tang Brookhaven National Laboratory Working on...

Introduction to CS/IT

Instructor:Yong-nian TangBrookhaven National LaboratoryWorking on accelerator control631-344-7022 (BNL Phone #)[email protected]@sunysuffolk.edu

2

Text Book:No required


3

Supply: USB drives to save files and transfer

data.

Very cheap when they are on sale. About $0.50 to $1 per GB, or even

less.

Every one should have one or two.


4

Course Web Pages:

www2.sunysuffolk.edu/tangy/cst111

Outline Announcements Slides Projects Attendance and project status


5

Attendance Policy

Attending classes is very important Firm but flexible policy If you can not attend a class,

• call 344-7022 or • email [email protected]

Attendance Grades: 10% goes to the final grade. However, more points will be deducted for many absences.


6

Fail or Withdrawal One should go to registrar to formally

withdraw from the class if quitting attending the class after some date. For example, one quits the class after the midterm exam.

If you forget to formally withdraw, I usually assign W as your final grade if the College permits. However, if you need to get an F in order to get financial aid, please send me an email.

If the College does not allow professors to assign W, I will assign F for lack of choices.


7

Grading Policy

Specified in the outline In general, if one attends the classes,

finishes lab work, exams and projects, one gets a relatively good grade.

Do not worry about grades, to learn something is more important.

No reasons to not get a good grade.


8

Topics Algorithms Internet and security Hardware: binary numbers, circuit gates Software:

Operating systems: Windows and FilesApplications: Excel and Access

High-level Programming: we’ll write real programs (in processing and Java)


Defining Computers

A computer is an electronic device accepts input processes and stores data produces output

Types of Computers

Personal computers• Desktop• Notebook (Laptop) • Tablet PC

Hand-helds: PDAs, MP3 players, Cell phones

Mainframes Supercomputers Other computers (at home, in car…)

Types of Computers

Personal computers are used for general computing tasks.

Hand-held computers fit in the palm of your hand and run on batteries.

Mainframes are used by companies to provide centralized storage, processing, and management for large amounts of data.

Supercomputers are the largest and fastest of computers, and can process an enormous volume of data.

Types of Computers

Desktop: (HP, Dell, IBM…)• Usually more powerful and cheaper

than laptops• Needs separate monitor, not easy to

move around• Could be replaced by laptops and

tablets in the near future?

Types of Computers

Notebook, Netbook & iPad• Small & lightweight.• Portable• Netbook: browsing• Internet• Tablets (7” and 10”)

Types of Computers

Supercomputers are the largest and fastest computers. BNL Bluegene

Mainframe s are very powerful computers, but not as powerful as supercomputers.

Clusters: consists of hundreds and more processors.

Computer Systems

A computer system is made up of: Hardware — the physical

components. Can be touched. If kicking it, your toe will get hurt.

Software — the programs or lists of instructions. Can not be touched.

Software could be more expensive than hardware. Why do most people KEEP using Windows system?

Can we reduce the weight of a computer by deleting its software (files).

No!!!

Software has no weight.

Hardware: major components

Motherboard CPU (Central Processing Unit) Memory Storage devices I/O (Input/Output) devices Network devices Power supply, case, video card,

sound card…

Hardware: Motherboard

Also called mainboard

Located inside the computer case

Holds and connects all essential components

Hardware: CPU

CPU - micro processor• A silicon chip

designed to manipulate data

• The brain of a computer.

• 64-bit CPUs and 32-bit CPUs

Hardware: CPU (cont.) Intel, AMD, Apple, IBM… make

CPUs. Its speed is determined by:

• Clock speed (Hz)• Word size (32-bit and 64-bit)• Processor type• Usually, motherboard and CPU are

the most expensive components in a computer. High-end video cards are not cheap either.

Question

1. What are the two most expensive components in a computer?

Hardware: Units of Memory and Storage Computer understands 0 and 1 only:

on/off state, N/S pole, 0/5 volts… 1 (“on”) and 0 (“off”) are referred to

as bits. Eight bits is a byte. Two bytes

represent a unique character (Unicode)

Decimal numbers and binary numbers.

Hardware: Units of Memory and Storage Everything in the computer memory

and storage devices is a number! A computer understands only numbers.

Number number Character number (ASCII code) Grey level number ( usually 0 – 255) Color three numbers (R/G/B)

Question

2. A byte can store 256 different numbers, why do we need two bytes to store an English character?

Hardware: units of Memory and Storage

Kilobyte (KB) = one thousand (1024) bytes

Megabyte (MB) = one million (1024 KB) bytes

Gigabyte (GB) = one billion bytes Terabyte (TB) = one trillion bytes

Hardware: Memory

Computer memory is a set of storage locations.

Five types of memory:• Random access memory (RAM)• Cache memory• Virtual memory• Read-only memory (ROM)• Complementary metal oxide

semiconductor memory (CMOS)

Hardware: Memory

RAM --- Random Access Memory• Sits on motherboard and closes to

CPU• Also called volatile memory,

primary memory, and main memory.

• Most important memory type.• 256 MB to many GBs.• Fast CPU + big memory + (fast

graphical card) a fast computer.

Hardware: Memory Cache memory

• Special high-speed memory chip on the motherboard or CPU

• Stores frequently and recently accessed data and commands.

• Usually 1 to ??? MB.• The bigger, the better, also more

expensive.

Hardware: Memory Virtual memory is extra memory that

simulates RAM if more is needed. Limited by the memory space (word size).

Read-only memory (ROM) is the permanent storage location for a set of instructions the computer uses.

CMOS memory is semi-permanent information about where essential software is stored.

Hardware: Storage Media

Magnetic storage devices • Hard disks—several magnetic oxide

covered metal platters usually sealed in a case inside the computer

• Tape—inexpensive, slow, archival storage for large companies who need to back up large quantities of data.

• Floppy disks: (almost) obsolete


Optical storage devices• CD-R - store 700 MB of data• CD-RW: not reliable• DVD—can store between 4.7 and 15.9

GB of data; Blue-ray discs and HD-DVD can store between 15 and 50 GB of data


Flash memory cards• Small, portable cards: rewritable• Used in digital cameras, handheld

computers, video game controllers, and other devices

• Most commonly-used: SD (HDSD) cards – Secure Digital.

Hardware: Storage Media USB drive, USB

flash drive• from 32 MB to 16 GB

and more • Plug directly into the

USB port (hot operation)

• Rewritable• Best portable storage• Small and

inexpensive: $1.50/GB

Hardware: Differences between memory & storage

Speed Persistent Size Location

Memory Fast No Limited On board

Storage Slow Yes Unlimited(?) External

Question

3. When we talk about memory and storage, how do you compare computers and people?

Hardware: Input/Output Input:

• Data you type• Data by reading files• Data through Internet.• Data from sensors……• Other sources

Output: The result of computer processing.

Hardware: Input/Output

Peripheral devices • Accomplish the input, output, and

storage functions.• Not sit on the motherboard

slow• I/O always is the slowest part of

any program execution

Hardware: I/O Devices

Input devices:

Keyboard Mouse Others


Output devices:• Monitors

CRT monitors (almost obsolete) LCD and LED

• Printers• Others


Monitor’s quality Screen Size

(diagonal in inches)

Resolution (in pixels)

Setting the screen resolution.


Types of printers• Laser• Inkjet

B/W printing:

buy laser printers Color laser printer:

very expensive cartridges. Inkjet printer

Hardware: Printer

Turn OFF the printer when not printing to prevent the heat from drying the cartridges.

Use the power button to turn off the printer in order to make cartridges stay in the proper housing. Do not pull the power cord.

Hardware: Video Card Integrated (on-board) and

dedicated video cards Gaming: needs high-end video

cards. High-end computers have

dedicated video-cards Usually, a video card has its own

memory; on-board video shares main memory.

43Microsoft Office 2007-Illustrated Introductory, Premium Video Edition

Hardware: Network Devices Network cables (Ethernet cables)

Modems and routers Wireless cards and adapters Building a home wireless network:

Not as hard as one thinks. Just follow the instructions.

A Desktop Computer

Motherboard and others

The Back of a Computer

Computer ports and connections

Power connection

Mouse port

FireWire port

Network port

Phone line connection

Speaker and microphone connections

USB ports

Monitor port

Audio connection

Keyboard port

The first class ends here

Software: major Components Operating system

• Windows• Unix & Linux (open and free)• MacOS

System utilities Application software

Software: Introduction

Software manipulates and processes data

Data:Strings, numbers, figures, sounds, images, and graphics…

Software: Introduction

File --- named collection of stored data.• Executable file can be run to perform

a specific task.• Data file contains data.

Everything in a computer is represented by a number on disk and in memory.

Software: Data Representations

Every English character is represented by an ASCII number.

ASCII numbers defined by ANSI. ANSI standard sample ASCII code


Software: Data Representations

ASCII --- American Standard code for Information Exchange

ANSI --- American National Standards Institute

Software: System Software

System software helps the computer carry out it s basic operating tasks.• Operating systems• Utilities• Device drivers• Programming languages

Software: System Software Operating system

• Executes programs• controls the input and output (I/O)• allocates system resources and priorities• Schedules tasks• manages files on storage devices• guards against equipment failure• provides a graphical user interface

(GUI)• Others

Software: System Software Operating system

• Programmer: develop and write the system

• System administrator (SA): configure and maintain the system

• End user: use the system Using GUI (Graphical User Interface) Manipulating files

57

Software: System Software Major Operating systems

• Windows by Microsoft: most recent version is Windows 7.

• Unix/Linux: many flavors (Sun Solaris, HP-UX, IBM AIX, Redhat, Debian, Ubuntu…)

• MacOS: only for Apple computers.

58


Which OS is better?• Windows: most popular. Easy to use.

Many applications. Hardware/software installation is easy. Prone to virus attacks.

• Unix/Linux: free. Popular in academic world. Hardware/software installation needs effort and expertise. More secure than Windows.

• MacOS: nice GUI, stable and reliable. Pay a premium because it’s Apple.

59


We are users and we learn• Basic knowledge of file systems.• To use GUI of the system• To configure the system• To maintain the system


Utilities • Analyze, configure, optimize and

maintain computer system: disk defragmenter, system restore…

Device drivers• “Drives” a specific device (drive). • The main task to install a device is to

install its driver.



Programming languages• Used by a programmer to

develop programs. • Most commonly used computer

language: C, C++, Java, C#, Visual Basic, Fortran…



Drive and Driver• Drive --- Hardware• Driver --- software to “drive” a

specific drive. Examples:

Hard (disk) drive --- Hard (disk) driverUSB drive --- USB driverPrinter --- Printer driver


Windows Vista starting screen

Icons (you might see additional

icons on your

screen)

Start button

Taskbar

Quick Launch toolbar

Gadgets (small programs; you might see additional or different gadgets on your screen)

Software: Application Software

Enables you to perform specific computer tasks

Examples: web browsers, Microsoft Office, DBMS, ……

Security Threats: virus (malware) Software programs infesting

computers: Worms, Trojan horse, spyware, adware…

Replicates itself and fill up disks Damages computer systems Erases files and wipes out disks Ties up network and computers.

Slows down program execution

66

Security Threats: viruses

Pops up ads Keylogger: steals personal

information Creates a back-door and lets

remote users access your computer

A bad virus spreads very fast and affects millions computers.

67

Security Threats: Sources of viruses

Downloading virus-infected files Opening malicious emails and their

attachments Infected disks and CDs Worst incidents: Melissa, ILOVEYOU

Security Threats: Anti-virus Firewall

• Stop unwanted and unsolicited incoming network messages and data.

• Can be either hardware or software. Antivirus software

• Every computer must equip with an antivirus software.

System and software update:• Automatic update

69

Security Threats: Antivirus

Microsoft: security_essentials (free) Paid: Norton, MacAfee, Trend Micro Free:

• ClamAV: open source. For Unix/Linux , also for Windows

• Clamwin: variant of ClamAV for Windows• Stopzilla• Avast!• AVG Anti-Virus

70

Security Threats: Antivirus

There is no excuse not to install an antivirus software, at least it should have security_essential installed fromwww.microsoft.com/security_essential

SE is free and works well!

Security Threats: Spoofed sites Spoofed site

• A Web site set up to look like another Web site, but which does not belong to the organization portrayed in the site

• The URL (address on the Web) looks similar to a URL from the legitimate site www.citibank.com and www.citybank.com

• Usually set up to try to convince customers of the real site to enter personal information

Security Threats: Phishing Phishing

• Sending e-mails to customers of a legitimate Web site (banks and institutions) asking them to click a link in the e-mail because of Security upgrade Account update Account compromised Other reasons

• If the customer does not click the link, his/her account will be suspended or closed

• the link leads to a spoofed site and asks personal and/or login information.

Security Threats: Other tricks Nigerian scams

• Lottery winner, request processing fee• Unclaimed treasure: needs your account

number to deposit Over-payment scam

• You sell an item (a car…)• A far-away guy will buy it and send you a

bank check larger than your asking price• He asks you to mail the extra to himself

or someone else through western union…• You deposit the check and send the extra

back (real money). Several weeks later, the check bounced.

Security Threats: Phishing

Too good to be true >>> not true Never open an unsolicited email,

especially, its attachments Never reveal your personal information

(SSN, bank account number, credit number…) unless you initialize the communication

Never make any payment to a (faraway) stranger.

Wait for the check cleared, then take action.

If someone specifically ask you to send money through Western Union or Money Gram most likely it’s a scam.

Security Threats: Phishing

To clear a bank check needs one to several weeks, especially foreign checks.

Payment by Western Union… is not traceable.


Security Threat: Strong password At least eight characters long

Consists of upper- and lowercase letters and numbers

Does not include common personal information

Security Threats: Encryption

Encrypt important files especially when files are on a USB drive.

TrueCrypt: free and easy to use for Unix, Linux, and Windows.

Computer Languages

First generation: machine language

Second generation: Assembly language

Third generation: High level such as C, Fortran, C++, Java, VB…

79

Programming languages

First generation: machine language: • Consists of 0’s and 1’s• The only language understood by computers• Fast and efficient• Very hard to program, read and understand.• Used in the old times.

Introduction to Programming

80


Second generation: assembly language: • English words are used in a very cryptic way• Needs an assembler to convert it to machine

language• Relatively fast and efficient• Still hard to program, read and understand; but is

doable. The core parts of OS’s are usually coded in assembly language

• Different hardware (CPUs) has different assemblers


81


Third generation: high level language: • C, C++, Java, C#,VB, Fortran,…• English-like language• Developing programs by writing source code• Source code (compiler or interpreter) assembly

language (assembler) machine language • Still fast and efficient for most tasks• Relatively easy to program, read and understand• Portable to almost all platforms.


Irvine, Kip R. Assembly Language for Intel-Based Computers 6/e, 2010. 82

Translating LanguagesEnglish: Display the sum of A times B plus C.

C++: cout << (A * B + C);

Assembly Language:mov eax,Amul Badd eax,Ccall WriteInt

Intel Machine Language:A1 00000000F7 25 0000000403 05 00000008E8 00500000

83

What are programs? A program is a sequence of instructions

written in computer languages to guide computers to perform tasks.

A computer follows the instructions exactly and precisely. --- an important observation of computer programming.


84

An example

To calculate the average of two numbers• Input: get the two numbers• Processing: calculate their average• Output: display the result


Software Development

Source code (text file) Interpreter and compiler

convert the source to object code (.obj)

Linker links all object codes and libraries into executable files. (.exe)

86

Compiler and Interpreter

Compiler converts the whole program from source code to machine code, generates an executable program.• Source files object files (.obj)• A linker links all the object files and library functions an

executable program (.exe) Interpreter converts the source code one line/block

at a time and execute it.• Advantage: easy to develop and debug the program• Disadvantage: slow


Software Development

Java uses a different approach in order to make it portable.

Source code (text file, .java) Java compiler javac convert the

source to byte code (.class) Java Virtual Machine (JVM)

interprets the byte code and run the program.

88

Write a fast program

The slowest part of a program is I/O:• Reduce I/O times as much as possible• Use buffers to do I/O

A fast computer make a program running fast: Fast CPU (32-bit vs. 64-bit) Big memory (32-bit machine can access only 3.7

Gb) Good video card if you like to play fast games


Software DevelopmentOOP and Procedural

• Object-Oriented Programming (OOP): Java

• Procedural (Conventional) programming: C

• What are the differences between them?

Software DevelopmentClient and Server

• In a distributed environment• A server provides services• A client requests services• The opposite: peer-to-peer

system.

Software DevelopmentLife Cycle

• Analysis and design• Coding• Testing and Debugging• Maintenance

Software DevelopmentComments

• Line comments: starts with //, ends at the end of line

• Block comments: /* … */• Comments make the code

more readable and easy to understand.

Software DevelopmentComponents of a program

• Basic: data types and operations,…

• Code structs: decisions, loops, functions

• Data structures: arrays, classes, and others.

Units of Memory and Storage

Computer understands 0 and 1 only: on/off state, N/S pole, 0/5 volts…

1 (“on”) and 0 (“off”) are referred to as bits.

Eight bits is a byte. Two bytes represent a unique character (Unicode)

Software DevelopmentMemory organization

Bit (0 or 1)Byte: 8 bits (0 to 255)Word: system dependentKilobyte: 1 k (1024) bytesMegabyte: 1 M byte (1024 x

1024)Pay attention to data types.

Units of Memory and Storage

Kilobyte (KB) = one thousand (1024) bytes

Megabyte (MB) = one million (1024 KB) bytes

Gigabyte (GB) = one billion bytes Terabyte (TB) = one trillion bytes

Data Representations

Everything is a number in the computer memory or on storages• Numbers numbers• Characters numbers by ASCII• Grey numbers (0-255)• Color three numbers (R/G/B)

Software DevelopmentNumber system

Binary number (0,1): base 2Octal number (0,1,2,…,7):

base 8Example: o1, o7, o23

Decimal number (0,1,2,…,9): base 10

Hexadecimal number (0,1,2,…,9,A,B,C,D,E,F)

Example: 0x1, 0x8, 0xf, 0xff

Irvine, Kip R. Assembly Language for Intel-Based Computers 6/e, 2010.

Character Storage

Character sets• Standard ASCII (0 – 127)• Extended ASCII (0 – 255)• ANSI (0 – 255)• Unicode (0 – 65,535)

Start processing!

Introduction to CS/IT Instructor: Yong-nian Tang Brookhaven National Laboratory Working on...

Documents

Transcript of Introduction to CS/IT Instructor: Yong-nian Tang Brookhaven National Laboratory Working on...