ENGR2216FORTRAN PROGRAMMING FOR ENGINEERS

Chapter 1The computerCPUMEMORYINPUT/OUTPUT DEVICESDATA REPRESENTATIONBINARY SYSTEMOCTAL & HEXADECIMALDATA TYPESHISTORY OF FORTRANEVOLUTION OF FORTRAN

Computers: are they important?Solving problems in any fieldCan you imagine a computer without software (programmes)?Computers success is tied to programming

Where do we find computers?In a grocery store: scanners checking pricesATM (Automatic Teller Machines)MobilesMicrowave ovenCarsDo you believe that the first electronic computer was invented about 60 years ago?

Basic Definitions

A computer:is a special type of machine that stores information and can perform mathematical calculations on that information at speeds much faster than human beings can think.A program:tells the computer what sequence of calculations are required and on which information to perform the calculations.

Examples of ProgrammesA computer at the bank stores customers information.Another programme can check each customers account daily. Once it goes below 100 Rials, the customer gets charged 1 Rial.Another programme can monitor the customers account, and send an sms message to the customers informing them that its time to take out their Zakat.Another program: when your phones battery becomes low, it gives you a warning: low battery.

Computers vs. HumanAre computers smarter than human?No, they only process programmes faster.They follow the instructions given in a programme.They cant think on their own.They must be told what to do and when to do itA clever programme means a clever programmer

The computerCPU = computers heartCPU = Control + ALU + memoryControl: controls all PC partsALU: performs calculationsMemory: temporary storage of results during calculationsControl: Interpret instructionsFetch data from inputSend data from memory to output devices or main memoryE.g. multiply 2 3

Main memory

Secondary memory

Input devices

Output devices

InternalMemory(registers)

ArithmeticLogicunit

Controlunit

Central Processing Unit

The computerMain memory (e.g. RAM)PrimaryVolatileSemiconductor chipVery fastFetch time 60 nsExpensiveStore currently used programmeSecondary memory (e.g. HDD)Non-volatile explain!Higher capacity (80GB vs. 1GB)SlowerCheaper

Main memory

Secondary memory

Input devices

Output devices

InternalMemory(registers)

ArithmeticLogicunit

Controlunit

Central Processing Unit

The computerInput devices Purpose: enter data/informationExamples:KeyboardMouseScannerCameramicrophoneOutput devices Purpose: display resultsExamples:Monitors/ LCDsPrintersPlottersspeakers

Main memory

Secondary memory

Input devices

Output devices

InternalMemory(registers)

ArithmeticLogicunit

Controlunit

Central Processing Unit

The binary number system(725)10 = 7 102 + 2 101 + 5 100Used by human

(101)2 = 1 22 + 0 21 + 1 20Used by computers

Examples:Find the following:(111)2 = ()10(011)2 = ()10(00001110)2 = ()10Byte = 8 bits

How many possible values can we make with a 3-bit binary number? Hint: (000) to (111)HOW TO CONVERT FROM BASE 10 TO BASE 2?The 2n rule.

Data representation in a computerWhat is a computer memory composed of ?Millions of ON/OFF switchesHow does a PC store data in memory?A switch is either ON (1) or OFF (0)A single switch can represent only 1 or 0.What does bit mean?BIT stands for Binary DigitA bit is either 1 or 0.1 Byte = 8 bits representing a binary numberE.g. memory of 256 MB (megabytes) = 256 million bytesE.g. hard disk drive with storage of 40 gigabytes = 40 billion bytes1 word = 2, 4, (or more) consecutive bytes = 32, 64, bitsHow many possible values can we make with 1 byte?28 = 256 possible values (-128 to 127)

Binary (2), Octal (8) and Hexadecimal (16)

Types of Data stored in memoryEach type needs a different amount of memoryCharacter Data:UPPER CASE LETTERS (A-Z) = 26Lower case letters (a z) = 26Digits (0 9) = 10Symbols: , ( ) [ ] ! ~ @ # $ % ^ & * .Special letters or symbols (e.g. )Total number < 256 1 byte per character1,000 characters need 1,000 bytesFor non-English languages, more characters are used)Task: read text book for ASCII coding and EBCDIC coding

Integer DataReal Data (floating point)

Types of Data stored in memoryEach type needs a different amount of memoryCharacter DataInteger Data:-ve integers, +ve integers, and zeroNeeds 1, 2, 4, or 8 bytes (differs from one computer type to another)In any computer that uses n-bit integer:Smallest integer = -2n-1Largest integer = 2n-1 1(why -1?)What happens if a larger number is used?Task: read text bookError: Overflow condition Real Data (floating point)

Types of Data stored in memoryEach type needs a different amount of memoryCharacter DataInteger DataReal Data (floating point):Used for fractional numbers (e.g. 0.25)Used for very large or very small integersValue = mantissa 2exponentE.g. speed of light in decimal system = 2.998 108 m/sComputers use base 2 system, with 32 bits (4 bytes) of computer memory:24 bits for mantissa8 bits for exponentTask: read text bookPrecisionRangeRound-off error

Computer LanguagesMachine languageA program is a list of operations to be executed by a computer:E.g. load, store, add, subtract, etc.Each operation has a binary pattern (e.g. add = 1011) called op codeThe data associated with the op code are called operandsA set of op codes is called machine languageE.g. add 3,41011 0011 0100 store A 0101 0000 1010Machine language is very hard for humanHigh level languages:Easy to write/understandList of instructionsConvert to machine language using compilers and linkersExamples of high level programming languages:BasicC++COBOLFortranJava

FORTRAN LanguageGrandfather of all scientific computer languagesFORmula TRANslationTranslate formula into a computer codeFirst FORTRAN: 1954 1957 By IBM for 704 computers

FORTRAN LanguageGrandfather of all scientific computer languagesFORmula TRANslationTranslate formula into a computer codeFirst FORTRAN: 1954 By IBM for 704 computersIntegers and real data types onlyNo subroutinesFORTRAN II: 1958FORTRAN IV: 1962 (stayed for 15 Years)FORTRAN IV: 1966 (adopted as ANSI standard, and called FORTRAN 66FORTRAN 77: 1977 (introduced IF statements, and simplified using characters)Fortran 90: 1992 Fortran 95: 1996Text book covers both 90/95Task:Read sections 1.4, and 1.5 of the text book