Number of Keys in XT, AT and Enhanced Keyboard

When I started teaching Computer Science in High Schools, the widely used text book for the subject was R. C. Khanal’s Computer Concept published by Ekata Books Distributors Pvt. Ltd -one of the largest text books publishers in Nepal. This book was almost the only text book followed in high school level Computer Science which is still true for many schools.

Later on many other books appeared. But they were clearly influenced by R. C. Khanal’s book. Almost everybody rewrote the Computer Concept in their own words. This resulted in duplicating the errors Khanal made in his book.  One funny error was in the number of keys in different types of keybords.

The number of keys for different types of keyboard mentioned in the books was:

1. XT Keyboard (83 keys)

2. AT Keyboard (101 keys)

3. Enhance Keyboard (103 keys)

It is not the case only in Computer Concept. Even later editions of this book and all other books published after it repeated the information. The whole generation crammed these numbers.

What is the number of Keys in XT Keyboards, AT Keyboards and Enhanced Keyboards?

There are three types of keyboards regarding the model – XT, AT and Enhanced.

XT Keyboards (83 Keys)

The very first PC keyboard was the old 83-key keyboard used by IBM for the very first IBM PCs and PC/XTs in the early 1980s.

Immediately after the release of this keyboard IBM had to undergo through numerous complains on its design. It resulted mostly from those who were accustomed of IBM electronic typewriter. Following are the reasons that necessitated redesigning sooner:

    Cramped Physical Grouping:-

Many keys are of odd sizes, and there is no clear vertical "dividing line" for the eye between the main typing area and the numeric keypad. Even the function keys are not separated very much from the rest of the layout. Overall, it looks like a "jumble of keys"
    Poor <Shift>, <Enter>, <Control> Keys Size and Location 
    No Dedicated Cursor and Navigation Keys
    No Indicator LEDs
    Left-Side Function Keys

Source: The PC Guide (http://www.PCGuide.com)

AT Keyboards (84 Keys)

It was due to the feedback of its users on XT Keyboards, IBM redesigned the layout and launched along with its new IBM/AT computers.

The layout much improved, isn’t it? Numeric Keypad is separated as well as function keys. Other keys too are much improved and justifying their size and location.

It was really teasing to think “What was than one key added on AT Keyboard?” Almost all of the keys were rearranged.

The added key was “SysReq” stands for system request. You can find this key shared with Prt Scr (Print Screen) key on your keyboard. Read for more information about SysReq key.

Enhanced Keyboards (101 Keys)

In 1986, IBM introduced the IBM PC/AT Model 339. Included in this last AT-family system was the new Enhanced 101-key keyboard. Little did IBM realize at the time, perhaps, but this 101-key keyboard would become the de-facto standard for keyboards for the next decade and beyond. Even today’s Windows keyboards and fancy variants with extra buttons and keys are based on this layout.

Windows Keyboard (104 Keys)

Its interesting to know that Microsoft – a dominant software company designs, manufactures and sells some input devices time and again. It might be due to the popularity of Windows operating system, they felt it necessary to provide some short cut keys on keyboard to let users access windows features directly. Following is the Windows Keyboard with 104 keys:

Sources: Widipedia (http://en.wikipedia.org)

The PC Guide(http://www.pcguide.com/)

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Tags: AT Keyboard, Computer Operator, Enhanced Keyboard, Exam Preparation, Number of Keys in Keyboards, Type of Keyboards, XT Keyboard