First Generation (1940-1956) Vacuum Tubes

The first computers used vacuum tubes for circuitry and magnetic drums formemory, and were often enormous, taking up entire rooms. They were very expensive to operate and in addition to using a great deal of electricity, generated a lot of heat, which was often the cause of malfunctions.

First generation computers relied on machine language, the lowest-level programming language understood by computers, to perform operations, and they could only solve one problem at a time. Input was based on punched cards and paper tape, and output was displayed on printouts.

The UNIVAC and ENIAC computers are examples of first-generation computing devices. The UNIVAC was the first commercial computer delivered to a business client, the U.S. Census Bureau in 1951.

Second Generation (1956-1963) Transistors

Transistors replaced vacuum tubes and ushered in the second generation of computers. The transistor was invented in 1947 but did not see widespread use in computers until the late 1950s. The transistor was far superior to the vacuum tube, allowing computers to become smaller, faster, cheaper, more energy-efficient and more reliable than their first-generation predecessors. Though the transistor still generated a great deal of heat that subjected the computer to damage, it was a vast improvement over the vacuum tube. Second-generation computers still relied on punched cards for input and printouts for output.

Second-generation computers moved from cryptic binary machine language to symbolic, or assembly, languages, which allowed programmers to specify instructions in words. High-level programming languages were also being developed at this time, such as early versions of COBOL and FORTRAN. These were also the first computers that stored their instructions in their memory, which moved from a magnetic drum to magnetic core technology.

The first computers of this generation were developed for the atomic energy industry.

Third Generation (1964-1971) Integrated Circuits

The development of the integrated circuit was the hallmark of the third generation of computers. Transistors were miniaturized and placed on silicon chips, called semiconductors, which drastically increased the speed and efficiency of computers.

Instead of punched cards and printouts, users interacted with third generation computers through keyboards and monitorsand interfaced with an operating system, which allowed the device to run many different applications at one time with a central program that monitored the memory. Computers for the first time became accessible to a mass audience because they were smaller and cheaper than their predecessors.

Fourth Generation (1971-Present) Microprocessors

The microprocessor brought the fourth generation of computers, as thousands of integrated circuits were built onto a single silicon chip. What in the first generation filled an entire room could now fit in the palm of the hand. The Intel 4004 chip, developed in 1971, located all the components of the computer—from the central processing unit and memory to input/output controls—on a single chip.

In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced the Macintosh. Microprocessors also moved out of the realm of desktop computers and into many areas of life as more and more everyday products began to use microprocessors.

As these small computers became more powerful, they could be linked together to form networks, which eventually led to the development of the Internet. Fourth generation computers also saw the development of GUIs, the mouse and handhelddevices.

Fifth Generation (Present and Beyond) Artificial Intelligence

Fifth generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used today. The use of parallel processing and superconductors is helping to make artificial intelligence a reality. Quantum computation and molecular and nanotechnology will radically change the face of computers in years to come. The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and self-organization.

Computer Basics Equipment (Hardware)

COMPUTER	A machine that processes information and performs computations.
Tower or Desktop	The "box" or case that holds the parts that make up a computer: CPU, hard disk drive, floppy drive, memory chips, power supply, interface cards, etc.Click here to learn more.
CPU	Central Processing Unit, or "brains" of the computer
Monitor	An output display device (looks similar to a TV) in a computer system. You see information on the monitor's screen.
Screen	The viewing area on a monitor or the information or image displayed.

Disk Drive	A device that reads data from (input) or records data onto a disk for storage (output).
Floppy	Floppy Drive	. 3-1/2" Floppy Disk
Hard Drive	The main device that a computer uses to store information. Most computers come with a hard drive, called drive C, located inside the computer case.
CD-ROM	ROM means Read-Only-Memory - you can only "read" information, not save.A CD can store a large amount of data including documents, photographs, software, and music (about 20 songs)
	CD Drive	Compact Disk
	CD-R A CD-Recordable drive can put data onto a disk in just one session, and then is "closed" - one "burn" only - you can't add to it after you create it.	CD-RW A CD-ReWritable drive can be written onto more than once - similar to a floppy or hard disk.
DVD-ROM	Digital Video Disk - Read-Only Memory	Used to store full-length movies, large programs, etc.
CD's, CD-R's, CD-RW's, and DVD's all look the same. You must read the label to determine what type of media it is. Both CD's and DVD's are optical storage media. Optical technology uses a laser or light beam to process information.
USB Flash Drive		These can hold documents, picures, and music. Some flash drives are also MP3 players.

Mouse	A hand-held input device you roll on your desk to point to and select items on your screen. When you move the mouse, the mouse pointer on the screen moves in the same direction.
Mouse pointer	The little symbol on your screen that you move with your mouse. You use the mouse pointer to point to and select items on your screen. The mouse pointer changes shape, depending on its location on your screen and the action you are performing.
	Left Mouse Button - usually use this button
	Right Mouse Button - occasionally use this button for "special" actions
	Scroll Wheel - the mouse wheel may work differently from program to program. and it may not work in some programs. In most word processing programs, you can rotate the wheel to move up or down the page, equivalent to using the PAGE UP or PAGE DOWN keys on your keyboard or to clicking the scroll bar. Due to various problems it is best if you do not use the scroll wheel in the computer lab.
Click	Press and quickly release the button on a mouse
Double Click	Press and quickly release the mouse button twice.
Drag	Move objects or data around on the screen through the use of a mouse. Keep the left mouse button pressed while you move the mouse.
Speakers	Output device that produces sound and music when connected to the computer. Speakers come in different shapes and may even be in the monitor's case.
Headphones	Output device for listening that is held over the ears by a band worn on the head
Microphone	Input device in which sound energy is changed into electrical energy for the sending or recording sound (your voice).
Scanner	Input device that reads copy as an image and digitally records the image
Digital Camera	Records and stores images as a digital file, operates similarly to a "normal" camera, but no "film" is needed
Projector	Output device for displaying onto a large surface (projection screen) what appears on the computer monitor.
Printer
	A device that produces a paper copy of the information on your screen. The printer on the left is an INK JET PRINTER, and the other is a LASER PRINTER.
.	.
Hub
	Hubs are devices that have many ports into which network cables are plugged. A hub takes the signal from each computer and sends it to all of the other computers through the network. Hubs come in different sizes and colors. The hub must be plugged in and turned on for the network to work - be sure you see green lights
Modem	A device that allows computers to communicate with each other over telephone lines (Internet). At school we do not use modems, we have a direct connection to the Internet called a T-1 line.
Keyboard	Input device - choose letters, symbols, and actions by pressing keys
Key	Any of the buttons on a keyboard that the user presses to input data (information) or to type commands
Escape	Usually pressed while you are working in a software application to stop the current activity, back out of a menu (or screen), or return to a previous screen.
Enter	Used to move the cursor to the beginning of a new line. It may also be called the return key. In some applications, pressing Enter tells the computer to stop waiting for more input and begin processing. Notice the arrow symbol on the Enter key; it is sometimes used in instructions and means to press the enter key.
Backspace	Moves the cursor one space to the left, erasing any character that is in its path
Spacebar (split spacebar)	Moves the cursor one space to the right, leaving a small blank white area (space) on the screen.	If the spacebar is "split", the left "spacebar" acts like the backspace key - it erases the character to the left of the cursor.

shift	Does nothing by itself, but when pressed and held down with another key it makes either a capital letter or the upper character on a key. Pressing Shift with a letter key when the CAPS LOCK key is "on" makes a lower case letter.
caps lock	Makes all letters uppercase without having to use the shift key - it is best to only use this when you are going to make many letters uppercase - don't use for just a few capital letters
tab	Marked with two arrows, one pointing left, the other, right. If pressed by itself, it moves the cursor to the next tab on the right. When pressed with the Shift key, it moves the cursor to the previous tab stop on the left.
alt	Does nothing by itself. When pressed with another key, it performs a special function. For example, pressing Alt-F4 may quit a currently running program.
ctrl	Does nothing by itself. When pressed with another key, it performs a special function. For example, pressing Ctrl-S may "save" a document.
Num Lock	Typically "on" at start up. When "on", it changes the keys on the numeric keyboard from cursor control arrows to numbers arranged in a typical ten-key calculator keypad.
Delete	On our "Windows" computers (P) it erases the character to the right of the cursor. Some people say it performs a "forward erase". It operates differently on a MAC.
End	The key you press to move the cursor to the end of the current line. Many programs also use keyboard shortcuts such as Ctrl+End to move the cursor to the end of a document.
Insert	Changes between insert mode and overstrike mode in word processing programs. In insert mode, all characters typed are placed at the cursor position (or to the right of the insertion point). As you type, anything to the right of the cursor moves to the right to make room for the new typing. If insert mode is turned off, typing then overwrites (erases) the old characters instead of putting the new ones before the old ones. This is often called overwrite mode. Most PC keyboards have an Ins or Insert key that lets you switch back and forth between insert and overwrite modes. Many word processing programs display OVR in a status bar at the bottom when overwrite mode is on.
Home		The key you press to move the cursor to the beginning of the current line. Many programs also use keyboard shortcuts such as Ctrl+Home to move the cursor to the beginning of a document.
PgDn	The function of this key is usually software specific. Typically, it scrolls a document backward one screen or one page.
PgUp	The function of this key is usually software specific. Typically it scrolls a document forward one screen or one page.
Arrows	4 keys that move the cursor in the direction the arrow points
Function Keys (F1, F2 ...)	Special keys that perform a number of important tasks. Their exact functions are software dependent. F1 usually is reserved for Help, while F10 frequently exits or quits the program.
Print Screen	It directs the computer to copy whatever is displayed on the screen to the clipboard for pasting later. It doesn't really "print" in Windows.
Scroll Lock	Its function is often software specific. In spreadsheets, it usually locks the cursor on its current screen line and scrolls text (rather than the cursor) up or down whenever an up or down cursor control arrow is pressed.
Pause	Not usually used with Windows. Pressing this key under DOS temporarily stops a screen display or freezes rapidly scrolling information.
Windows Key	The WINDOWS key acts as another special function key. If you press the Window key by itself, the Start Menu will open. Windows+E will launch Windows Explorer.