In 1972 IBM introduced flexible disks as a medium for loading programs into mainframe computers. Because the disks were so flexible, they were nicknamed floppy disks. They are enclosed in a protective jacket that has openings for the drive spindle, the read/write head, the timing hole, and a write-protect notch that allows the user to prevent data from being written over inadvertently.

Floppy disks were the most popular storage medium for personal computers as well as for stand alone data entry systems, office word processing systems and smaller computer systems. The disks are available in three standard sizes: 3 ½, 5 ¼ and 8 inch-size. The storage capacity of 3 ½ inch disks is greater than that of 5 ¼ inch disks. This is because the smaller floppy disks have a higher data density.

The density of a disk is measured in two ways. First, the track density, or number of tracks on the disk, is measured in tracks per inch. Second, the bit or linear density is the number of bits per inch per track. Early floppies have a track density of 48 tracks per inch and a linear density of 2800 bits per inch and came to be known as single density disks. Though technological improvements, the track and linear density of floppy disks has increased and therefore the capacity of the disks has also increased.

You probably know all this stuff, but…

Email is one of the oldest uses of computer networks. In fact, email predates the World Wide Web by more than two decades. Email was one of the first applications that was used to transport information on the Internet, when the Internet was nothing more than a few interconnected computers.

Today, email is used by millions of users across the world. There are different styles of email addressing, however the most popular email address format is the domain style address (used with the Internet and other TCP/IP networks). The email address consists of a user name and domain name, separated by an @ sign. For example:

john_doe@gmail.com

In order to use email you need an email address and a client that enables you to get your email, manage your email messages and send messages. Most email providers provide a browser-based interface. Although mail messages were originally plain text, and still are in most cases today, there are some newer features that let you enable the kinds of content that you can send and receive such as:

- Attachments: You can attach to your mail messages. Attachments can contain data that you couldn’t ordinarily keep in a mail message, such as a binary program, a word processing file or an image. The recipient of the mail attachment can either save the file to a local hard disk or open it in a program designed to read the attachment.

- HTML: The same stuff used to create web pages can be included in mail messages you create with certain mail clients. This lets you change fonts and colors, add backgrounds, insert images, or add HTML features.

Depending on the email client you are using, email management features let you direct incoming email into different folders and sort messages by date, sender, or other attributes, email sending features let you reply to messages, forward messages and draw names from an address boor or directory server.

There are three different types of computers namely analog, digital and hybrid.

~ Analog Computer operates by measuring physical units such as voltage, pressure, temperature, speed, etc. Analog computers are used for scientific and engineering applications that deal with a property which is changing continuously.

~ Digital Computer operates on numbers consisting of 0′s and 1′s. These two numbers are called binary values. The characters and words are also represented in the binary form. Digital computers are useful for business as well as scientific and engineering applications. The term computer is commonly used in place of digital computers most of the people take it for granted.

~ Hybrid Computer combines analog and digital capabilities, which are used for special purposes. ‘ROBOT’ is the best example of a hybrid computer.

The first operational digital computer was the ENIAC (Electronic Numerical Integrator and Calculator). It was developed in 1946 by John Mauchy and J. Presper Eckert at the university of Pennsylvania.

Professor John Von Neumann gave the idea of stored program concept which is the key concept in the design of today’s computers. According to stored program concept, the program and its associated data must be stored in a high speed memory during execution of a program.

EDVAC (Electronic Discrete Variable Automatic Computer) was the first stored program computer and it became operational in 1951.