Introduction to Programming Instructor: Yong Tang Brookhaven National Laboratory Working on accelerator control 631-344-7022 (BNL Phone #) [email protected].

Introduction to Programming

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

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Text Book:Learning Processingby Daniel ShiffmanPublisher: Morgan Kaufmann


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Do we need to buy the text book?

It is recommended that you buy the book.

However, you can survive without it.


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Supply: USB drives to save files and transfer

data.

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

Every one should have one or two.

Introduction to Computing

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Course Web Pages:

www2.sunysuffolk.edu/tangy Outline Announcements Slides Projects Data files for projects and exercises Answers to some exercises


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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]

Absences Grades


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Grading Policy

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

finishes lab work, exams and projects, one can pass the course

Pay attention to the attendance policy Do not worry about grades, to learn

something is more important


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Objective Learning computer programming.

Please notice that the language processing is only a tool.

One should be able to write medium-size and relatively complex programs.


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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.


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An example

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


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Programming Languages

Programming Language analogy:• Each computer has a native machine

language (language L0) that runs directly on its hardware

• A more human-friendly language is usually constructed above machine language, called Language L1


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Programming Language analogy:• Each computer has a native machine

language (language L0) that runs directly on its hardware

• A more human-friendly language is usually constructed above machine language, called Language L1


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Programming Language analogy (Cont.)• Programs written in L1 can run two different

ways:Interpretation – L0 program interprets and executes

L1 instructions one by oneTranslation – L1 program is completely translated

into an L0 program, which then runs on the computer hardware


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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.


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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


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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.


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

Specific Machine Levels

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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


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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


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)

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)


Every English character is represented by an ASCII number.

ASCII codes are defined by ANSI.

Two bytes for a character (Unicode)


Decimal number: base 10 --- 0,1,2,…,9

Binary number: base 2 --- 0,1 Octal number: base 8 --- 0,1,2,…7 Hexadecimal number: base 16 ---

0,1,2,…9,A,B,C,D,E,F

Binary Numbers

Digits are 1 and 0• 1 = true• 0 = false

MSB – most significant bit

LSB – least significant bit

Bit numbering

015

1 0 1 1 0 0 1 0 1 0 0 1 1 1 0 0

MSB LSB

Binary Numbers Each digit (bit) is either 1 or

0 Each bit represents a power

of 2:

1 1 1 1 1 1 1 1

27 26 25 24 23 22 21 20

Every binary number is a sum of powers of 2

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

Translating Binary to DecimalWeighted positional notation shows how to

calculate the decimal value of each binary bit:

dec = (Dn-1 2n-1) + (Dn-2 2n-2) + ... + (D1 21) + (D0 20)D = binary digit

binary 00001001 = decimal 9:

(1 23) + (1 20) = 9

Binary Addition

Starting with the LSB, add each pair of digits, include the carry if present.

0 0 0 0 0 1 1 1

0 0 0 0 0 1 0 0

+

0 0 0 0 1 0 1 1

1

(4)

(7)

(11)

carry:

01234bit position: 567

Integer Storage Sizesbyte

16

8

32

word

doubleword

64quadword

What is the largest unsigned integer that may be stored in 20 bits?

Standard sizes:

Hexadecimal Integers

Binary values are represented in hexadecimal.

Irvine, Kip R. Assembly Language for Intel-Based Computers 6/e, 2010. 32

Translating Binary to Hexadecimal• Each hexadecimal digit corresponds to 4 binary bits.

• Example: Translate the binary integer 000101101010011110010100 to hexadecimal:


Converting Hexadecimal to Decimal

Multiply each digit by its corresponding power of 16:

dec = (D3 163) + (D2 162) + (D1 161) + (D0 160)

Hex 1234 equals (1 163) + (2 162) + (3 161) + (4 160), or decimal 4,660.

Hex 3BA4 equals (3 163) + (11 * 162) + (10 161) + (4 160), or decimal 15,268.


Character Storage

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

Introduction to Programming Instructor: Yong Tang Brookhaven National Laboratory Working on accelerator control 631-344-7022 (BNL Phone #) [email protected].

Documents

language l1 introduction

assembly language

language processing

important introduction

result introduction

humanfriendly language

exercises introduction

computer hardware introduction