CPSC- 120 Principle of Computer Science I Computer

CPSC- 120 Principle of Computer Science I Computer = Hardware + Software

Hardware b. Main Memory b. Secondary Memory b. Central Processing Unit (CPU) b. Input Devises b. Output Devises

Main Memory b Random Access Memory (RAM) b storing information and programs b information such as numbers, names, lists, pictures b An ordered sequence of storage locations called memory cell b each memory cell has associated with it a unique address

Secondary Memory b Additional storage capability on most computer such as a disk drive b hard disk, floppy disk, CD b inexpensive b more information can be stored measured by megabyte or gigabytes

Central Processing Unit (CPU) b Control computer operations b Perform arithmetic and logical operations b each operation is performed less than one millionth of a second b To process a program, CPU • fetches each instruction • decodes the instruction • executes the instruction

Input and Output Devices b Output • Monitor, Printer b Input • Keyboard, Mouse

Software b. Operating Systems- - UNIX, Windows b. Application Programs - - Word Processor, Spreadsheet b. Software Development Tools - - compiler, editor

Steps in the Software Development Method b Problem Specification b Analysis b Design b Test Plan b Implementation or coding b Testing

Case Study b Refer to page 21

Programming languages b Machine Languages b Assembly Languages b High-Level Languages

Example Ada Program WITH Ada. Text_IO; PRODECURE Hello IS ----------------------------------- A very simple program; it is just displays a greeting. ---------------------------------BEGIN -- Hello Ada. Text_IO. Put(Item => “Hello there. “); Ada. Text_IO. Put(Item => “We hope you enjoy studying Ada!”); Ada. Text_IO. New_Line; END Hello;

Chapter 3 The General Structure of Ada Programs

Displaying Initials Program WITH Ada. Text_IO; PROCEDURE Hello_Initials IS -------------------------------| Requests, then displays, user's first and last initials. --| ------------------------------Initial 1 : Character; -- objects that hold initials Initial 2 : Character;

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 => Initial 1); Ada. Text_IO. Get(Item => Initial 2); -- Display user's initials, with a greeting Ada. Text_IO. Put(Item => "Hello "); Ada. Text_IO. Put(Item => Initial 1); Ada. Text_IO. Put(Item => Initial 2); Ada. Text_IO. Put(Item => ". Enjoy studying Ada!"); Ada. Text_IO. New_Line; END Hello_Initials;

Reserve Words and Identifiers b Reserve Words With Procedure IS Begin END

b Predefined Identifiers Ada. Text_IO Put New_Line Character Get

Displaying the User’s Name WITH Ada. Text_IO; PROCEDURE Hello_Name IS -------------------------------------| Requests, then displays, user's name --| ------------------------------------First. Name: String(1. . 10); -- object to hold user's name

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 => First. Name); -- Display the entered name, with a greeting Ada. Text_IO. Put(Item => "Hello "); Ada. Text_IO. Put(Item => First. Name); Ada. Text_IO. Put(Item => ". Enjoy studying Ada!"); Ada. Text_IO. New_Line; END Hello_Name;

Ada’s Capabilities b Control Structures b Data Structures b System Structures