Computer HistoryYou might be surprised about how far back the history of computers goes. Nowadays a computer is defined as a machine that stores and processes information and that can be programmed to carry out instructions. But computer used to refer to the actual person that computed often using a device like the abacus or the slide rule.

The first programmable machine was invented in 1801. It was a loom, a machine for weaving cloth. Invented by French weaver Joseph-Marie Jaquard , the loom was strung with punched cards that let colored threads through to form different patterns.

A few decades later in 1837 British Mathematician Charles Babbage realized that these punch cards could also store numbers and other data. Using this technology Babbage designed a computer he called the Analytical Engine. Although he never managed to build the entire machine Babbage was a major computer science pioneer. His punched data cards were used in computers through the

1970’s. The U.S. government used a punch card machine to conduct the 1890 census (a report on population trends). Babbage also developed the “conditional statement”, a program that lets computers select from a set of actions to perform.

Computer technology really started to improve in the 20th century. A number of different machines could claim the title of earliest computer. It really just depends on your definition of the word computer.

The Z3 built by German Conrad Zuse in 1941 was the first programmable computer that wasn’t tied to a specific function like weaving cloth or calculating bills.

In 1944 Harvard University and IBM joined up to build the Mark I, a giant calculator that could perform any number of mathematical equations. It ran on an electric motor and weighed 5 tons.

The Electronic Numeral Integrator & Calculator (ENIAC) was introduced in 1945. Even bigger than the Mark I, ENIAC could perform 5000 operations per second which was huge at the time. In fact, it was so powerful that it was used to help build the Hydrogen Bomb.

A lot of these early computers were built by hand so each machine was one of a kind. They were very expensive and fragile. They were huge, taking up whole rooms that had to be specially air conditioned so the machinery would not overheat.

But in 1959, miniature electronic devices called Integrated Circuits were invented. This meant that millions of transistors (the switches that control the flow of electricity in a computer) could be mass produced. Transistors were tiny compared to the vacuum tubes they

replaced. Computers became even smaller and more powerful with the invention of the microprocessor, a silicon chip that could hold thousands of transistors and other electrical parts. This made computers small, cheap, fast, and accessible. By the 1970’s there were handheld calculators more powerful than those room size computers of the 1940’s. And in 1977, Apple

produced what became the first popular home computer, the Apple II. Meanwhile, microprocessors kept getting smaller. Now millions of transistors can fit on a piece of silicon the size of a finger nail. Software tools like word processors, spreadsheet programs, email, and the World Wide Web made personal computers useful to ordinary people.

Computers have worked their way into other technologies such as household appliances, cars, and toys. Computers are likely to keep getting smaller, faster, cheaper, and more powerful for a long time.

Computer Basics

Computer Types: Introduction

Computers are showing up everywhere you look, and even in places you can't see. Computers check out your groceries, pump your gas, dispense money at the ATM, turn the heat on and off, control the way your car runs. They're everywhere! They're everywhere! In fact, the computer is rapidly becoming, if it hasn't already gotten there, as tightly woven into the fabric of our lives as the automobile. The analogy runs quite deep.

When automobiles were new, many people said "Those smelly, loud, complicated things will never replace the horse!" And "Those things break down in just a few miles, while my faithful horse goes on and on and repairs itself!" Nowadays it's hard to imagine the world without all the variety of four-wheeled, internal combustion vehicles. How many can you name? Sedans, pickup trucks, fire engines, front-end loaders, 4-wheelers, golf carts, bulldozers, cranes, vans, dump trucks... We have an "automobile" for every purpose under heaven - and in different models and colors, too.

Do you know all these vehicles?

. So it is with computers. There are different kinds of computers for different purposes. They are just as varied in size, expense, and ability as our more familiar 4-wheeled vehicles are.

What is a computer?A computer is an electronic device that executes the instructions in a program.

A computer has four functions:

a. accepts data Input

The Information Processing Cycle

b. processes dataProcessing

c. produces output Output

d. stores resultsStorage

In the lessons that follow we will study the parts of the computer and each of the four parts of the Information Processing Cycle.

Some Beginning Terms

Hardware the physical parts of the computer.

Software the programs (instructions) that tell the computer what to do

Data individual facts like first name, price, quantity ordered

Information data which has been massaged into a useful form, like a complete mailing address

Default the original settings; what will happen if you don't change anything.

What makes a computer powerful?

Speed A computer can do billions of actions per second.

Reliability Failures are usually due to human error, one way or another. (Blush for us all!)

Storage A computer can keep huge amounts of data.

Computer Types:  Descriptions

There is a computer for every use under heaven, or so it seems. Let's look at the kinds of computers that there are, based on general performance levels.

Personal or microComputers for personal use come in all shapes and sizes, from tiny PDAs (personal digital assistant) and smart phones to hefty PC (personal computer) towers. More specialized models are announced each week - trip planners, expense account pads, language translators... To make things even more interesting, categories are blending together. Phones are getting really, really smart.

Smart phone PDA Tablet PC Laptop/Notebook

Desktop Tower

Descriptions of Personal Computers

When talking about PC computers, most people probably think of the desktop type, which are designed to sit on your desk. (Bet you figured that one out!) The tower and the smaller mid- and mini-tower style cases have become popular as people started needing more room for extra drives inside. Repairmen certainly appreciate the roominess inside for all the cables and circuit boards ... and their knuckles.

A workstation is part of a computer network and generally would be expected to have more than a regular desktop PC of most everything, like memory, storage space, and speed. It's hard to tell the difference any more.

The market for the smallest PCs is expanding rapidly. Software is becoming available for the small types of PC like the palmtop (PPC) and handheld (HPC). This new software is based on new operating systems like Windows CE (for Consumer Electronics). You may find simplified versions of the major applications you use. One big advantage for the newer programs is the ability to link the small computers to your home or work computer and coordinate the data. So you can carry a tiny computer like a PalmPilot, Blackberry, or a smart phone around to enter new phone numbers and appointments and those great ideas you just had. Then later you can move this information to your main computer. You may be able to use the Internet to view documents and even do some editing.

With a Tablet PC you use an electronic stylus to write on the screen, just like with a pen and paper, only your words are in digital ink. The Tablet PC saves your work just like you wrote it (as a picture), or you can let the Hand Recognition (HR) software turn your chicken-scratches into regular text.

Main Frame The main frame is the workhorse of the business world. A main frame is the heart of a network of computers or terminals which allows hundreds of people to work at the same time on the same data. It requires a special environment - cold and dry.

Supercomputers The supercomputer is the top of the heap in power and expense. These are used for jobs that take massive amounts of calculating, like weather forecasting, engineering design and testing, serious decryption, economic forecasting, etc.

Distributed or Grid ComputingThe power needed for some calculations is more than even a single supercomputer can manage. In distributed computing, using a PC grid, many computers of all sizes can work on parts of the problem and their results are pooled. A number of current projects rely on volunteers with computers connected to the Internet. The computers do the work when they are not busy otherwise. 

The projects that need distributed computing are highly technical. For example, the SETI@Home project looks for signs of intelligent communication in radio signals coming from space. (SETI stands for Search for Extra-Terrestrial Intelligence.) 

If you volunteer your computer for this project, you might be asked to load a small screen-saver program onto your own computer. When the computer is not busy, the screen saver comes on. The program downloads some signal data, starts to analyze it, and later reports the results back to SETI@Home.  Once the program is installed, you do not have to do anything else but watch the progress in the screen saver. 

Another method does not use a screen saver, but uses any idle time on your computer to work on the project. Results are sent to the project's home over the Internet.

Other Important Terms

Server

The term server actually refers to a computer's function rather than to a specific kind of computer. A server runs a network of computers. It handles the sharing of equipment like printers and the communication between computers on the network. For such tasks a computer would need to be somewhat more capable than a desktop computer. It would need:

more power larger memory

larger storage capacity

high speed communications

Minicomputer

The minicomputer has become less important since the PC has gotten so powerful on its own. In fact, the ordinary new PC is much more powerful than minicomputers used to be. Originally this size was developed to handle specific tasks, like engineering and Computer Aided Design (CAD) calculations that tended to tie up the main frame.