Computer Science Chapter 1

Object Code

-Preprocessor reads the source code -searches fro lines beginning with # symbol with contains demands and directives. -Next phase complier translate source code into appropriate machine language. Which searches for syntax errors. -Free of syntax errors the complier stores the translated machine language instructions.

Numeric Data

0 1 2 3 4 5 6 -2 03 -123 =Real Numbers 3.14158 6.7 1.0003 =floating point numbers Dealing with C++ Must know what type of data you are dealing with.

Designing and Creating a Program

1. Define What the program is to do 2.Visualize he program running on the computer 3.Use design tools to create a model of the program 4.Check the model for logical errors 5.Write the program source code 6.Complie the source code 7.Correct ay errors found during compilation. 8.Link the program to create an excitable file 9.Run the program using test data for input. 10.Correct any errors found while running the program.Repeat tips 4 through 10 as many times as necessary. 11.Validate the results of the program.

Computer Typical Consist of:

1.The Central Processing Unit (CPU) 2.Main Memory 3.Secondary storage Devices 4.Input Devices 5.Out Put Devices

Floppy Disk Drive

Another secondary storage which records data onto a small, flexible which can be removed from the computer.They have decline dramatically over the years due to the favor of the superior USB drives.

Input Devices

Any information the computer collects from the outside world. Devices that collected the information and sends it to the computer is called an input device. Common input devices are keyboard, mouse, digital camera, and microphone. CD/DVD'S, USB, are considered input devices as well.

Output Devices

Any information the computer sends to the outside world. Common output devices are computer devices, computer screens, printers, and speakers. CD/DVDS, Disk drives and USB are considered output devices.

Logical Errors/Logic Errors

Are mistakes that cause a program to produce erroneous results.

USB Drive (Universial Serial Bus)

Are small devices that plug into the computer USB universal serial bus appear to the system as a disk drive. CD and DVD can be use a drive as well which use lasers and optical disk in series of bits as well.

Machine Language

CPU can only process instruction that are written in machine language. Program consists of a sequence of binary numbers. (Consisting only 1s and 0s.) which CPU interprets as commands. Examples are 10111010000000101. Each computer has different language. Which why programing languages were created with words to make it easier.

high level language

Closer tot eh level of human-readability than computer-readability.

Operating System

Most fundamental set of programs on a computer. Controls the internal operations of the computer hardware and manages all the devices on the computer. Allows data to be saved to and retrieved fro storage devices and allows other programs to runoff the computer.

Run Time Error

Occurs when the ruling the program asks the computer to do something that is impossible (like divide by zero)

Operators

Operators perform operations on one or more operands. An operand is usually a piece of data, like a number.

Central Processing Unit (CPU)

Part of the computer that runs the program. The most important part. Job of the CPU is to fetch instructions, follow instructions, and produce results. Consists of two parts. Control Unit ad Arithmetic and Logic Unit.

Utility Programs

Perform a specialized task that enhances the computers operation or safeguards data. Examples are virus scanner, file-compression programs, and data-backup programs.

System Software

Programs that control and manage the basic operations of a computer. 3 Types. Operating System, Utility Programs, and Software Development Tools.

Application Software

Programs that make a computer useful for everyday task. The programs where people spend most of their time on. Examples are Microsoft Word, powerpoint, and presentation program.

Hardware

Refers to the physical components that a computer is made of.

Punctuation

Rules that must be followed when construction a program. Syntax dictates how key words and operators may be used and where punctuation symbols must appear.

Programmers/Software Developers

Software also known as programs are created by these individuals.

Software Engineering

The complete process of creating computer software. Includes designing, writing,testing,debugging,documenting,modifying,and maintaining come software development projects. Software engineers use a number of tools in their craft like program specifications, charts and diagrams of the screen output, hierarchy charts,pseudocode, examples of elected input and desired output, special software designed for testing programs.

Disk Drive

The most common type of secondary storage. Stores data magnetically encoding it onto a circular disk. Most computers have a disk drive mounted inside their case. Their are also external drive which connects to one of the computers communication ports and are used to create backup copies of data or move data to another computer.

Software Development Tools

The software tools that programmers use to create , modify, and test software are refereed to as software development tools. Compliers and integrated development environments.

Input, Processing, and Output

The three primary activities of a program

Variable Definiton

There are two types of data numbers and characters. Numbers of for mathematical operations and characters are used to rent information on the screen and to print on paper. All variables must be defined before hey can be sued cause he variable definition causes the variables to be created in memory.

Bytes

These are what the computer memory are divided into. One byte is enough memory to store just a single letter or an alphabet or a small number. Computer needs a lot of these to do anything reasonable. Computers today have millions or billions bytes of memory. Each byte are assigned an address from lowest to highest. Like a post office.

Integrated Development Environments

These environments consist of ext editor, complier,debugger,and other utilities integrated into a package with a single set of menus. Processing, compiling , linking, and even executing a program is done with a single click of a button, or by selecting a single item from a menu.

Programmer-Defined Identifiers

Words or names defined by the programmer. They are symbolic names that refer to variables or programing routines.

Key Words

Words that have special meaning. Keywords may only be used for their intended purpose. Keywords are also known as reserved words.

Source Code

Written in a text editor where source code is written, typed, and saved into a file.

Statement

Is a complete instruction that causes the computer to perform some action.

Pseudocode

Is a cross between human language and a programming language. Helps the programmer to focus on the logical steps.

Hierarchy Chart

Is a diagram that graphically depicts the structure of a program. It has boxes that represents each program. Boxes are connected in a way to illustrates their relationship to one another. Takes an overall task and makes them simpler in each step. Also known as divided and conquer and top down design.

Flow Chart

Is a digram that shows the logical flow of a program. Useful tool for planning each operation a program must perform and the order in which the operations are to occur.

Variables

Is a named scrooge location in the computer's memory for holding a piece of data. They are symbolic names that represents locations in the Computer's RAM.

Desk-Checking

Is a process that help locates the run time and logic errors that occurs in the program.

Program

Is a set of instructions that a computer follows to perform a task.

Computer Program

Is a set of instructions that tells the computer how to solve a problem or perform a task.

Algorithm

Is a set of well-defined steps for performing a task or solving a problem. (Instructions needs to be performed in their proper sequences.)

Programming Language

Is a special language used to write computer programs.

Secondary Storage

Is a type of memory that can hold data for long periods of time even when the computer is off. Frequently used programs are stored here and loaded to the main memory.

low level languages

Is close to the level of the computer, which means it resembles the numeric machine language of the computer more than then the natural language of humans.

Control Unit (1 of two parts of CPU)

It is responsible for determineing where to get the next instruction and regulating the other major components of the computer with control signals.

Main Memory (Random Access Memory ) (RAM)

Known as the computer work area. Stores program here while running. Usually a volatile type of memory that is used only for a temporary storage while program is running. When computer is off all the contents in RAM are erased.

Software

Computers is under control of the software. Two general categories are System Software and Application Software.

Arithmetic and Logic Unit (ALU) (1of two pars of CPU)

Design to perform mathematical operations.

Executable File

During the last phase of the translation process a linker combines the object file with the necessary library routines. This file contains machine language instructions and is ready to run on the computer.

Bit (Binary Digits)

Each byte is divided into smaller storage locations called bits. bits are shot for binary digits. Computer Scientist think of them as on/off switches. They are really tiny electron charges that hold ether a positive or negative charge. Positive on and negative is off.