history of computers

The first electronic digital computer was called "ENIAC" built in 1945 in Philadelphia. It used so much electricity that lights in the nearby town dimmed every time it was used! What a long way we have come in a half-century, with personal computers in homes, offices, and schoolrooms across the world.

After the arrival of the microprocessor, many different computer companies appeared and began developing their own microprocessors and microcomputers. Companies such as Apple, Compaq, and Commodore started during this period of confusion. At the conclusion of the timeline is the first home personal computer or PC, by IBM in 1981.

Computers began to steadily and rapidly increase in speed and power while becoming more compact and more user friendly from the early 1980's on. The progress, however came in many small steps, rather than fewer major events like earlier years.

From the start of the decade to today, PCs in the home have become immensely popular. Computers have increased their role from professional and business machines to entertainment and educational tools. Telecommunications advancements such as the Internet have shown themselves to be useful both in education and business.

Hard disks or Computer hardware were invented in the 1950s. They started as large disks up to 20 inches in diameter holding just a few megabytes. They were originally called "fixed disks" or "Winchesters" (a code name used for a popular IBM product). They later became known as "hard disks" to distinguish them from "floppy disks." Hard disks have a hard platter that holds the magnetic medium, as opposed to the flexible plastic film found in tapes and floppies. At the simplest level, a hard disk is not that different from a cassette tape. Both hard disks and cassette tapes use the same magnetic recording techniques.

A typical desktop machine will have a hard disk with a capacity of between 10 and 40 gigabytes. Data is stored onto the disk in the form of files. A file is simply a named collection of bytes. The bytes might be the ASCII codes for the characters of a text file, or they could be the instructions of a software application for the computer to execute, or they could be the records of a data base, or they could be the pixel colors for a GIF image. No matter what it contains, however, a file is simply a string of bytes. When a program running on the computer requests a file, the hard disk retrieves its bytes and sends them to the CPU one at a time.

The Internet was the result of some visionary thinking by people in the early 1960s who saw great potential value in allowing computers to share information on research and development in scientific and military fields.

The Internet, then known as ARPANET, was brought online in 1969 under a contract let by the renamed Advanced Research Projects Agency (ARPA) which initially connected four major computers at universities in the southwestern US.

The Internet was designed in part to provide a communications network that would work even if some of the sites were destroyed by nuclear attack.

The early Internet was used by computer experts, engineers, scientists, and librarians.
E-mail was adapted for ARPANET by Ray Tomlinson of BBN in 1972. He picked the @ symbol from the available symbols on his teletype to link the username and address.

As the commands for e-mail, FTP, and telnet were standardized, it became a lot easier for non-technical people to learn to use the nets.

Most Internet Service Providers or( ISP’s ) make use of these protocols in E-mail, Usenet newsgroups, file sharing, the World Wide Web, Gopher, session access, WAIS, finger, IRC, Mud’s, and Mush’s. Of these, e-mail and the World Wide Web are clearly the most used, and many other services are built upon them, such as mailing lists and web logs. The Internet makes it possible to provide real-time services such as web radio and web casts that can be accessed from anywhere in the world.

The Internet is also having a profound impact on knowledge and worldviews. Through keyword-driven Internet research, using search engines, millions worldwide have easy, instant access to a vast amount and diversity of online information. Compared to encyclopedias and traditional libraries, the Internet represents a sudden and extreme decentralization of information and data.

A current trend with major implications for the future is the growth of high speed connections. 56K dialup modems are not fast enough to carry multimedia, such as sound and video except in low quality. But new technologies many times faster, such as cable modems, digital subscriber lines (DSL), and satellite broadcast are widely available now, and growing fast. The rapid growth of local networks, even in homes, has increased the demand. Common methods of home access include dial-up, broadband and satellite communications.

As the commands for e-mail, FTP, and telnet were standardized, it became a lot easier for non-technical people to learn to use the nets. It was not easy by today's standards by any means, but it did open up use of the Internet to many more people in universities in particular. Other departments besides the libraries, computer, physics, and engineering departments found ways to make good use of the nets--to communicate with colleagues around the world and to share files and resources.

We have come a long way in computer technology since the ENIAC. Now eighty percent of American households have at least one computer, and most households have one computer exclusively for the use of PC games, music, videos, and surfing the web.

FYI: "The American PC game market is a $1.2 billion business. Five years ago a talented programmer and an artist could make a hit. Today a state-of-the-art game is a multimillion-dollar collaborative product."

spam

Spam is unsolicited e-mail on the Internet. (E-mail that is wanted is sometimes referred to as ham.) From the sender's point-of-view, spam is a form of bulk mail, often sent to a list obtained from a spambot or to a list obtained by companies that specialize in creating e-mail distribution lists. To the receiver, it usually seems like junk e-mail.

Spam is roughly equivalent to unsolicited telephone marketing calls except that the user pays for part of the message since everyone shares the cost of maintaining the Internet. Spammers typically send a piece of e-mail to a distribution list in the millions, expecting that only a tiny number of readers will respond to their offer. It has become a major problem for all Internet users.

The term spam is said to derive from a famous Monty Python sketch ("Well, we have Spam, tomato & Spam, egg & Spam, Egg, bacon & Spam...") that was current when spam first began arriving on the Internet. SPAM is a trademarked Hormel meat product that was well-known in the U.S. Armed Forces during World War II.

search engine

On the Internet, a search engine is a coordinated set of programs that includes:
A spider (also called a "crawler" or a "bot") that goes to every page or representative pages on every Web site that wants to be searchable and reads it, using hypertext links on each page to discover and read a site's other pages
A program that creates a huge index (sometimes called a "catalog") from the pages that have been read
A program that receives your search request, compares it to the entries in the index, and returns results to you

An alternative to using a search engine is to explore a structured directory of topics. Yahoo, which also lets you use its search engine, is the most widely-used directory on the Web. A number of Web portal sites offer both the search engine and directory approaches to finding information.

ip address

This definition is based on Internet Protocol Version 4. See Internet Protocol Version 6 (IPv6) for a description of the newer 128-bit IP address. Note that the system of IP address classes described here, while forming the basis for IP address assignment, is generally bypassed today by use of Classless Inter-Domain Routing (CIDR) addressing.

In the most widely installed level of the Internet Protocol (IP) today, an IP address is a 32-bit number that identifies each sender or receiver of information that is sent in packets across the Internet. When you request an HTML page or send e-mail, the Internet Protocol part of TCP/IP includes your IP address in the message (actually, in each of the packets if more than one is required) and sends it to the IP address that is obtained by looking up the domain name in the Uniform Resource Locator you requested or in the e-mail address you're sending a note to. At the other end, the recipient can see the IP address of the Web page requestor or the e-mail sender and can respond by sending another message using the IP address it received.

An IP address has two parts: the identifier of a particular network on the Internet and an identifier of the particular device (which can be a server or a workstation) within that network. On the Internet itself - that is, between the router that move packets from one point to another along the route - only the network part of the address is looked at.

what is virus?

In computers, a virus is a program or programming code that replicates by being copied or initiating its copying to another program, computer boot sector or document. Viruses can be transmitted as attachments to an e-mail note or in a downloaded file, or be present on a diskette or CD. The immediate source of the e-mail note, downloaded file, or diskette you've received is usually unaware that it contains a virus. Some viruses wreak their effect as soon as their code is executed; other viruses lie dormant until circumstances cause their code to be executed by the computer. Some viruses are benign or playful in intent and effect ("Happy Birthday, Ludwig!") and some can be quite harmful, erasing data or causing your hard disk to require reformatting. A virus that replicates itself by resending itself as an e-mail attachment or as part of a network message is known as a worm.

Generally, there are three main classes of viruses:

File infectors. Some file infector viruses attach themselves to program files, usually selected .COM or .EXE files. Some can infect any program for which execution is requested, including .SYS, .OVL, .PRG, and .MNU files. When the program is loaded, the virus is loaded as well. Other file infector viruses arrive as wholly-contained programs or scripts sent as an attachment to an e-mail note.

System or boot-record infectors. These viruses infect executable code found in certain system areas on a disk. They attach to the DOS boot sector on diskettes or the Master Boot Record on hard disks. A typical scenario (familiar to the author) is to receive a diskette from an innocent source that contains a boot disk virus. When your operating system is running, files on the diskette can be read without triggering the boot disk virus. However, if you leave the diskette in the drive, and then turn the computer off or reload the operating system, the computer will look first in your A drive, find the diskette with its boot disk virus, load it, and make it temporarily impossible to use your hard disk. (Allow several days for recovery.) This is why you should make sure you have a bootable floppy.

Macro viruses. These are among the most common viruses, and they tend to do the least damage. Macro viruses infect your Microsoft Word application and typically insert unwanted words or phrases.

The best protection against a virus is to know the origin of each program or file you load into your computer or open from your e-mail program. Since this is difficult, you can buy anti-virus software that can screen e-mail attachments and also check all of your files periodically and remove any viruses that are found. From time to time, you may get an e-mail message warning of a new virus. Unless the warning is from a source you recognize, chances are good that the warning is a virus hoax.

The computer virus, of course, gets its name from the biological virus. The word itself comes from a Latin word meaning slimy liquid or poison.

what is internet?

The Internet, sometimes called simply "the Net," is a worldwide system of computer networks - a network of networks in which users at any one computer can, if they have permission, get information from any other computer (and sometimes talk directly to users at other computers). It was conceived by the Advanced Research Projects Agency (ARPA) of the U.S. government in 1969 and was first known as the ARPANET. The original aim was to create a network that would allow users of a research computer at one university to be able to "talk to" research computers at other universities. A side benefit of ARPANet's design was that, because messages could be routed or rerouted in more than one direction, the network could continue to function even if parts of it were destroyed in the event of a military attack or other disaster.

Today, the Internet is a public, cooperative, and self-sustaining facility accessible to hundreds of millions of people worldwide. Physically, the Internet uses a portion of the total resources of the currently existing public telecommunication networks. Technically, what distinguishes the Internet is its use of a set of protocols called TCP/IP (for Transmission Control Protocol/Internet Protocol). Two recent adaptations of Internet technology, the intranet and the extranet, also make use of the TCP/IP protocol.

For many Internet users, electronic mail (e-mail) has practically replaced the Postal Service for short written transactions. Electronic mail is the most widely used application on the Net. You can also carry on live "conversations" with other computer users, using Internet Relay Chat (IRC). More recently, Internet telephony hardware and software allows real-time voice conversations.

The most widely used part of the Internet is the World Wide Web (often abbreviated "WWW" or called "the Web"). Its outstanding feature is hypertext, a method of instant cross-referencing. In most Web sites, certain words or phrases appear in text of a different color than the rest; often this text is also underlined. When you select one of these words or phrases, you will be transferred to the site or page that is relevant to this word or phrase. Sometimes there are buttons, images, or portions of images that are "clickable." If you move the pointer over a spot on a Web site and the pointer changes into a hand, this indicates that you can click and be transferred to another site.

Using the Web, you have access to millions of pages of information. Web browsing is done with a Web browser, the most popular of which are Microsoft Internet Explorer and Netscape Navigator. The appearance of a particular Web site may vary slightly depending on the browser you use. Also, later versions of a particular browser are able to render more "bells and whistles" such as animation, virtual reality, sound, and music files, than earlier versions.