The PC Keyboard: Its First Five Years

It all began on August 12, 1981. The IBM 5150, better known as the IBM PC, arrived on the market accompanied by a true computing revolution, full of compatible software and third-party hardware components. However, there was much to correct, improve, and expand on that platform. One of the elements that undoubtedly reflected the evolution of the IBM PC was its keyboard, which in just five years changed its general design four times.

When you read or hear on the internet that the old IBM keyboards were the best of their kind, those words don't come from fanaticism, but from something very obvious: They were built to last. In the era of the first IBM PC, keyboards cost a fortune, and everything went through them, from the most extreme data entry sessions to video games. Failures were not an option.

All modern keyboards share roots with those tanks, but it took half a decade for the 101-102 key "standard" to be carved in stone. Anyone who looks at the earlier designs probably wonders "how did they manage to use those keyboards", but to be honest, they made a lot of sense.

IBM PC (5150), 83 Keys, 1981

Let's start with the most obvious: The function keys were ten and not twelve, placed in a 5 x 2 layout to the left of the keyboard. The Esc key's location, in the top left corner next to Tab and 1, also catches the eye, as does the position of the Ctrl key (where we now find Caps Lock) and that of Print Screen, just below the thin Enter. A single Ctrl and Alt in total, with no integrated LEDs. The code set of this keyboard is different. If someone plans to use it on a modern system, they will need to obtain or build a converter.

IBM PC AT (5170), 84 Keys, 1984

Beyond the similarities, the IBM AT keyboard introduced important changes. The function keys remain exactly in the same place, but the Esc key was moved to the numeric keypad, and spaces were inserted between Alt, Caps Lock, and the spacebar. Print Screen also moved to the numeric keypad. Debuting keys are System Request (which theoretically allows access to low-level functions, but in practice does nothing), and the "bigass" Enter in the shape of an inverted L.

At the same time, the IBM AT keyboard received LED lights indicating the state of Caps, Num, and Scroll Lock. Using this keyboard today requires converting its AT connector to PS/2, and from PS/2 to USB with an active signal converter.

IBM Enhanced, 101-102 Keys, 1984-86

So we come to the PS/2 series, which replaced all IBM PCs, XTs, ATs, and convertibles in one stroke. However, it's necessary to point out that the IBM Enhanced keyboard precedes the launch of that new line. It first came into action with IBM 3161 terminals, and its design takes inspiration from both the DEC LK201 and the 122-key keyboard belonging to the IBM 3270. By far, the most well-known Enhanced keyboard is the IBM Model M, in its American version 1391401.

A whole new row of top keys (twelve function keys), relocation of the Esc key, duplicate Ctrl and Alt keys, the thin Enter again, Caps Lock next to A, and a brand new cluster of secondary keys (Ins/Del, Home/End, PgUp/PgDn) define the IBM Enhanced keyboard. Its 102-key variant increases the size of the Enter key and makes the left Shift shorter, where we find the extra key.

IBM launched multiple variations of its keyboards, some of them very rare (and very sought after by collectors), but these five years establish the essence of the modern keyboard.

Sources: OS/2 Museum, Deskthority, Minus Zero Degrees