Microcomputer - is any computer with its arithmetic-logic unit(ALU) and control unit contained on one integrated circuit, called microprocessor. It can also be called a personal computer (PC) because it is designed to be used by a single user at a time.

The Computer System

Hardware the physical component of the computer system. It consist of the tangible parts of the computer.Central Processing Unit- referred to as the brain of the computer because all processing takes place in this part. It consist of the 3 parts, the ALU, Control Unit and the Memory Unit (Registers).The CPU may also be called the Microprocessor.

Inside a CPU

These three sections of the microprocessor work together to control the operations of the system. They are connected to the system bus and handle the input, output and storage of data.

Principal Parts of the CPU
1.Arithmetic- logic Unit (ALU)

Performs all arithmetic operations and logical processes required to solve a computer problem.

Arithmetic operations which include addition, subtraction, multiplication and division. All logic operations which involve comparisons such as less than, greater than, or equal to.

2. Control Unit- is the little supervisor of the CPU. It directs and coordinates the operations of the entire computer according to the instructions laid out in the program, interprets the instructions , gets the data to be used in each instructions and relays the hardware where action is to take place.

3.Memory Unit or Primary Storage Holds data or instructions. It is where the computer programs and data are stored during the processing. It is composed of electronic component called integrated circuits (ICs). It is divided into large number of storage cells that can hold data which are composed of characters.

Each character( can be a number, a letter or any symbol ) is stored as byte, however, bytes are formed by a group of 8 bits which is a fundamental unit and is equivalent to an electronic circuit that can either be on or off. So, a single character is considered one byte.

The unit of measure:

KB Kilobytes MB - Megabytes GB Gigabytes

Meaning and value of each symbol:

8 Bits = 1 byte

1 character = 1 byte

1 kilobytes (210) = 1,024 bytes(approx. 1000 bytes)

1 megabyte (220) = 1,048,576 bytes (approx. 1,000,000 bytes)

1 gigabyte (230) = 1,073,741,824 bytes (approx. 1,000,000,000 bytes

The Memory Unit contains two types of Memory:

Read-Only Memory (ROM) contains all system programs that are used for starting the operations of the computer. When purchasing your own unit, the system have already been installed thus, making the operation of the computer possible.It is the portion of a computers memory that does not lose its contents when you switch off the power, the system is hardwired so user cannot change nor delete.

2. Random Access Memory (RAM)

The computers primary working memory in which program instructions and data are stored so that they are accessible directly to the central processing unit (CPU). RAM is often called read/ write memory, to distinguish it from ROM.In RAM, the CPU can write and read data. If there is a system failure or power interruption, you lose all work in RAM that you have not saved.

Parts of the Computer

A computer system refers to a computer and all the input, output,and storage devices that are connected to it. A complete computer system consists of the CPU, Monitor, Keyboard, Mouse, and Speakers.

1. Monitor A device that displays text and graphics generated by the computer.

Monitors are categorize by the type of technology they use:

Cathode Ray Tube (CRT)Flat- panel Display uses liquid crystal display (LCD)

http://www.discovercomputers.info/ComputerMonitors/types2.html

2.Chassis It houses the brain of the computer.

3. CPU It controls the operation of the computer.

4. Keyboard It is used to type information into the computer or input information.

5. Mouse Is a device that you roll on a tabletop to move the cursor on the screen to make selection.

6. Speaker It emit sounds from the computer.

Components of the Computer System

A. Hardware the physical component of the computer system whether internal or external devices that are tangible in nature.

Types of Hardware Devices:

1. Input Device- brings data into the system.

ex. Keyboard Microphone

Mouse Barcode Reader

2. Output Device sends data out of the system.
ex. Monitor Printer
Speaker

3. Scanning Device - translates images
of text, drawing,and photos and the like
into forms of data that can be understood
by the computer.
Ex. Fax machine Scanners
4. Processing Device - is used to retrieve and execute the instructions in the form of computer programs provided by the computer.
Ex. Power Supply Motherboard
Ports

Storage Device Holds data that are not currently being used by the CPU

Ex. Floppy Disk Hard Disk

Compact Disk USB Flash Drive

6. Communication Device Performs both input and output, allowing computer to share information.

Ex. Modem

The Keyboard

a) Modifier Key: c) Navigation Keys

Control Key _ Arrow KeysShift Key _ Page Scroll KeysAlt Key (Page up/Page down)Windows Key _ Home Key/ End Key

Lock Key d) Edit Keys

Scroll Lock _ Return Key/Enter KeyNum Lock _ BackspaceCaps Lock _ Insert Key
_ Delete Key

_ Tab Key

e) SysRq / Print Screen
f) Break Key / Pause
g) Escape Key
h) Menu Key
i) Space Bar
j) Numeric Keypad
k) Function Keys
l) Power Management Keys a) Power key
b) Sleep key
c) Wake up key

Keys of the Keyboard

Escape Key- The Escape key, which is marked ESC on most keyboards, is basically used to exit or escape from programs and tasks.

Tab Key- This key is used to move the cursor over to the right to a pre-set point.

Backspace Key- This key is used to erase the character on the left of the cursor.

Caps Lock- this key is used to change lower case letters into capital letters.

Shift Key- this key is used to combine with alphanumeric keys to get upper case character. It can also be combined with Alt and Control keys to change the effect of other keys.

Enter Key- this key is used to enter a command or to go down a line in a document. It can also be used in place of a mouse click with buttons and drop down menus.

Control Key- this Ctrl key is used in conjunction with another key. Holding it down while pressing another key will initiate a certain action.

Delete Keys- this key is used to erase the character just to the right of the cursor.

Home Key- this is a navigation key and is used to move the cursor to the beginning of the current line.

End Key- This is a navigation key and is used to move the cursor to the end of the current line.

Page Up- This is a navigation key which will move the cursor up the displayed area one screens worth.

Page Down- This is a navigation key which will move down the the displayed area one screens worth.

Function Keys- These are programmable keys.

Space Bar- This key is used to enter blank spaces in text.

Num Lock Key- When this key is ON, the numeric keypad responds with the numbers as in adding machine but when this key is OFF, this key respond as a navigation keys using the alternate markings on the keys.

Numeric Keys- When the Num Lock Key is on, these keys are used to enter numbers

Pause/Break
This key was previously used in programming and debugging applications. In most current programs, it is non-functioning

Scroll Lock- is a toggle key that changes the effect of the cursor movement keys.

The Windows key can be found on some, but not all, keyboards that are used with Windows computers. The Windows key is marked with a small Microsoft W indows symbol and is usually found on the bottom row of the keyboard. There may be two Windows keyson each side of the space bar. Pressing the Windows key will bring up the Start menu.

Print Screen (PrtScrn)

In the old DOS days, the Print Screen key on a PC keyboard performed just as you would expect. When the Print Screen key is pressed, a paper copy of whatever on the screen is copied.

Arrow Keys
These keys are used to move the cursor on the screen.

The up arrow key is used to move the cursor one line up.

The down arrow key is used to move the cursor one line down.

The left arrow key is used to move the cursor one character to the left.

The right arrow key is used to move the cursor to the right.

SOFTWARE

It is a set of electronic instructions that tells the computer how to do certain tasks.

It consists of both Programs and Data. Programs are organized set of instructions for controlling the computers while Data can be any information that a program needs.

1. System Software- keeps all the hardware and software running together smoothly.

Example:

Operating System tells the computer how to interact with the user and its own devices.

2. Application Software- tells the computer how to accomplish tasks the user requires, such as creating a document or editing a graphic image.

Database Management

Graphics Programs

Web Design Tools

Spreadsheet Software

Desktop Publishing Software

Word processing Programs

Multimedia Authoring

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Integrated Circuit (ICs)

http://www.discovercomputers.info/ComputerMonitors/types2.html

http://en.wikipedia.org/wiki/Nick_Holonyak_Jr.

Father of the light-emitting diode".

Nick_Holonyak_Jr