CPSC- 120 CPSC- 120 Principle of ComputerPrinciple of Computer Science I Science I

Computer = Hardware + Computer = Hardware + SoftwareSoftware

HardwareHardware

Main MemoryMain MemorySecondary MemorySecondary MemoryCentral Processing Unit (CPU)Central Processing Unit (CPU)Input DevisesInput DevisesOutput DevisesOutput Devises

Main MemoryMain Memory

Random Access Memory (RAM)Random Access Memory (RAM) storing information and programsstoring information and programs information such as numbers, information such as numbers,

names, lists, pictures names, lists, pictures An ordered sequence of storage An ordered sequence of storage

locations called memory celllocations called memory cell each memory cell has associated each memory cell has associated

with it a unique addresswith it a unique address

Secondary MemorySecondary Memory

Additional storage capability on Additional storage capability on most computer such as a disk drivemost computer such as a disk drive

hard disk, floppy disk, CD hard disk, floppy disk, CD inexpensiveinexpensive more information can be stored more information can be stored

measured by megabyte or measured by megabyte or gigabytesgigabytes

Central Processing Unit Central Processing Unit (CPU)(CPU)

Control computer operations Control computer operations Perform arithmetic and logical Perform arithmetic and logical

operationsoperations each operation is performed less than each operation is performed less than

one millionth of a secondone millionth of a second To process a program, CPU To process a program, CPU

• fetches each instructionfetches each instruction• decodes the instructiondecodes the instruction• executes the instructionexecutes the instruction

Input and Output DevicesInput and Output Devices

OutputOutput• Monitor, PrinterMonitor, Printer

Input Input • Keyboard, Mouse Keyboard, Mouse

SoftwareSoftware

Operating Systems- - Operating Systems- - UNIX, WindowsUNIX, Windows

Application Programs - - Application Programs - - Word Processor, Word Processor, SpreadsheetSpreadsheet

Software Development Tools - - Software Development Tools - - compilercompiler, , editor editor

Steps in the Software Development Steps in the Software Development MethodMethod

Problem SpecificationProblem Specification AnalysisAnalysis DesignDesign Test PlanTest Plan Implementation or codingImplementation or coding TestingTesting

Case StudyCase Study

Refer to page 21Refer to page 21

Programming languagesProgramming languages

Machine LanguagesMachine Languages Assembly LanguagesAssembly Languages High-Level LanguagesHigh-Level Languages

WITH Ada.Text_IO;WITH Ada.Text_IO;PRODECURE Hello ISPRODECURE Hello IS------------------------------------------------------------------------------------------------------------------------------------------ A very simple program; it is just displays a greeting.-- A very simple program; it is just displays a greeting.-- -- -- ------------------------------------------------------------------ ----------------------------------------------------------------BEGIN -- HelloBEGIN -- Hello

Ada.Text_IO.Put(Item => “Hello there. “);Ada.Text_IO.Put(Item => “Hello there. “);Ada.Text_IO.Put(Item => “We hope you enjoy studying Ada.Text_IO.Put(Item => “We hope you enjoy studying

Ada!”);Ada!”);Ada.Text_IO.New_Line;Ada.Text_IO.New_Line;

END Hello;END Hello;

Example Ada ProgramExample Ada Program

Chapter 3Chapter 3

The General Structure of Ada The General Structure of Ada ProgramsPrograms

Displaying Initials ProgramDisplaying Initials Program

WITH Ada.Text_IO;PROCEDURE Hello_Initials IS-------------------------------------------------------

-------| Requests, then displays, user's first and last

initials.--|-------------------------------------------------------

-----

Initial1 : Character; -- objects that hold initials Initial2 : Character;

Cont.Cont.

BEGIN -- Hello_Initials-- Prompt for (request user to enter) user's initials Ada.Text_IO.Put(Item => "Enter your two initials> "); Ada.Text_IO.Get(Item => Initial1); Ada.Text_IO.Get(Item => Initial2);

-- Display user's initials, with a greeting Ada.Text_IO.Put(Item => "Hello "); Ada.Text_IO.Put(Item => Initial1); Ada.Text_IO.Put(Item => Initial2); Ada.Text_IO.Put(Item => ". Enjoy studying Ada!"); Ada.Text_IO.New_Line;

END Hello_Initials;

Reserve Words and Reserve Words and IdentifiersIdentifiers

Reserve WordsReserve Words

With With

ProcedureProcedure

ISIS

BeginBegin

END END

Predefined IdentifiersPredefined Identifiers

Ada.Text_IOAda.Text_IO

PutPut

New_LineNew_Line

CharacterCharacter

GetGet

Displaying the User’s Displaying the User’s NameName

WITH Ada.Text_IO;PROCEDURE Hello_Name IS-------------------------------------------------------

-------------------| Requests, then displays, user's name--| -------------------------------------------------------

-----------------

FirstName: String(1..10); -- object to hold user's name

Cont.Cont.

BEGIN -- Hello_Name -- Prompt for (request user to enter) user's name Ada.Text_IO.Put (Item => "Enter your first name, exactly 10 letters."); Ada.Text_IO.New_Line; Ada.Text_IO.Put (Item => "Add spaces at the end if it's shorter.> "); Ada.Text_IO.Get(Item => FirstName); -- Display the entered name, with a greeting Ada.Text_IO.Put(Item => "Hello "); Ada.Text_IO.Put(Item => FirstName); Ada.Text_IO.Put(Item => ". Enjoy studying Ada!"); Ada.Text_IO.New_Line;END Hello_Name;

Ada’s CapabilitiesAda’s Capabilities

Control StructuresControl Structures Data StructuresData Structures System StructuresSystem Structures