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[ The PC Guide | Systems and Components Reference Guide | Keyboards | Keyboard Layouts | Standard Keyboard Layouts ]

84-Key AT Keyboard Layout

Looking at the number of issues regarding the original 83-key XT keyboard, you can see that it's a pretty long list. Of course, in the early 1980s you didn't really have a lot of options. :^) Still, over time, IBM received a lot of complaints about the first keyboard design and eventually made improvements to it. The first evolution of the keyboard was the 84-key keyboard layout introduced with the first IBM PC/AT. Unsurprisingly, this is sometimes called the AT Keyboard.

Closeup photo of an IBM PC/AT clone keyboard, showing the 84-key keyboard layout.
(The LED indicators are above the numeric keypad and not shown in this photo.)

There are several definite improvements with this layout, compared to the 83-key keyboard:

  • Better Physical Grouping: The keyboard has three distinct key physical groups, with the numeric keypad placed distinctly to the right. The three groupings have clean vertical lines. The numeric keypad has been reorganized. Overall, the keyboard has a much more organized and understandable appearance.
  • Improved <Shift> and <Enter> Keys: The left <Shift> key and the <Enter> key have been enlarged, and the annoying "intervening" keys relocated.
  • LED Indicators: With the new internals of this keyboard (see below), LED indicators for the "lock" functions were added.
  • Extra "System Request" Key: This is the "84th key". It was mostly used for special control operations.

However, many of the layout issues with the original design remained. The biggest concern that remained unaddressed was the continued sharing between the numeric keypad, and the cursor and navigation keys. The function keys are still on the left-hand side, and the <Ctrl> and <Caps Lock> keys are still different from what a typist would expect.

Some PC users also believe that this keyboard layout took one step backwards, in relocating the <Esc> key. This key is used rather frequently, and moving it from a position where it could be easily hit with the left pinky or ring finger, to the numeric keypad, was an annoyance. I was among those to feel this way; others likely didn't care much. :^)

This keyboard was changed internally from the PC/XT model as well. The interface was made bidirectional, allowing the system to send commands to the keyboard, and enabling the control of the new LED indicators. The signaling and interface protocols created with this first PC/AT keyboard are still used today, even though the 84-key layout is no longer used, having been replaced by the "Enhanced" 101-key keyboard.

Next: 101-Key "Enhanced" Keyboard Layout


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