Monday, March 26, 2001		On Hardware

Key to computer at your fingertips
By Jasjot Singh Narula

COMPUTER without a keyboard is like a car without a steering wheel. Computing wouldn’t have been possible without the support of the keyboard. This is a device that has given a new dimension to computer industry.

Keyboard is a panel of buttons containing the alphabets, numbers and various symbols serving as one of primary devices for entering data into a computer system.

The innovative design of modern computer keyboard was fabricated from the basic typewriter, as we know it today, was patented by Christopher Latham Sholes in 1868. Some technological enhancements created the development of typewriter into computer keyboard.

Later, IBM launched keypunches in 1931, which was a combination of punch card system and typewriter. In 1946, the Eniac computer used a punch card reader, as its input and output device. Subsequently in 1948 Binac computer used an electromechanically controlled typewriter.

The dawn of computer keyboard started way back in 1964 with the collaboration of MIT Laboratories and General Electric to create Multics system. Electronic keyboard and video display terminals were used since the beginning of 1970 but the arrangement of the computer keys remained in QWERTY form, the same as in typewriter.

a) Typing keys

b) Numeric keys

c) Function keys

d) Control keys

As the name suggests, typing keys are the alphabet keys. Numeric keys are a set of 17 keys on the right hand side of the keyboard. Function keys are arranged in a line across the top of the keyboard and these could be assigned special commands by the current applications or operating system. Control keys provide cursor and screen control. Four keys arranged in an inverted T formation between typing keys and numeric keypad allows the user to move the cursor on the screen in increments. The control keys have the provision to make jumps in most applications. These keys are Home, End, Insert, Delete, Page up, Page down, Control (Ctrl), Alternate (Alt), Escape (Esc)

The keyboard has a microprocessor inside on a controller circuitry and the processor has to work out several things briskly.

Key switches detect the keystrokes. Their exact function is to convert the mechanical motion to electrical signal when the finger presses the key and sends to the processor of the keyboard. Keymartix is the grid arranged in rows and columns for recording data, such as in spreadsheet, of circuit below. Each circuit is broken at the point below a specific key. When a particular key is pressed, it generates a signal for the row and column assigned to the keys, allowing a tiny amount of current flow through. The processor determines the key matrix for sign of continuity at any point on the grid. When it finds a circuit that is closed, it compares the location of that circuit on the key matrix to the character map in its ROM (Read only memory). When keys press the key switch against the circuit, there is usually a small amount of vibration between the surfaces, known as bounce. So the processor filters such vibrations and treats it as a single key press. If the key is pressed spontaneously, the processor determines that the user wants the keys repeatedly to the computer, which is, know as typematics.

There are different keyboard switch technologies available for keyboards, which can either be mechanical, rubber dome, membrane, metal contact or foam element

Today rubber dome and membrane technology is most widely in use because they are inexpensive and have pretty good tactile response. These are also fairly resistant to spill and corrosion because of the rubber layer covering the keymartrix. Operation of the membrane keyboard is same as of rubber dome keyboard. One thing they differ on is membrane keyboard doesn’t have separate keys. In fact it has a single rubber-sheet with a hump for each key.

The processor in the keyboard is evaluating the keymatrix while the user is typing and determining what character to send to the computer. It maintains the data in the buffer of memory that is usually 16 bytes large and then sends the data via a cord through the connector as 5-pin DIN (Deustche Industrie Norm) connector or 6-pin IBM PS/2 mini-DIN connector.

A distinctive component of the computer, keyboard is often overlooked in terms of purchasing and maintenance. Today the market is flooded with many brands with variation in price and quality. There are different models that are available in the market with a difference in price and quality classified as:

1. 104-key window keyboard

2. Internet/multimedia ready keyboard

3. Ergonomic computer keyboard

4. Cordless keyboard

Internet/multimedia ready keyboards are a bit expensive but have some add-on features, like Internet keys which gives the user one-touch access to the Web and the user can play CDs and MP3 files, watch DVDs and change the volume.

Ergonomic keyboard have key arrangements that are considered to be better suited to the human hand. The keys are divided into two or three groups, with each group mounted at a different angle to the bottom of the keyboard. In many designs, the board is slightly higher in the middle than at the sides.

Cordless keyboard are the next generation keyboards, which brings flexibility, ease and comfort. But these pinch the normal users pocket, as on this day.