[shawndumas]

"Macintosh Keyboard (M0110): Introduced and included with the original Macintosh in 1984, it debuted without arrow keys to control the cursor nor an integrated numeric keypad." [1]

"Few will remember, but, when the Mac debuted in 1984, there were no arrow keys on the keyboard. That was a big deal. Almost every application then in existence depended on the arrow keys (then called cursor keys) for navigation. With that one stroke, Steve reduced the number of apps that could be easily ported to the Mac from tens of thousands to zero, ensuring that this new computer would have a long and painful childhood.

Steve’s button mania, which grew from his earlier parts-count mania, was already in full flower, and many have ascribed this crippling omission to some sort of self-destructive obsession. It was not. It was one of several strategies specifically designed to ensure that existing software would not run on this new machine because existing software, in Steve’s eyes, sucked (an opinion I share). The absence of those four keys ensured that any developer who wanted to have software appear on the Mac was going to have to start over and write software that conformed to the Mac interface, not the keyboard-oriented precursors to MS-DOS.

Steve’s fearless crippling of that original Mac saved that computer and saved the graphical user interface." [2]

1: http://en.wikipedia.org/wiki/Apple_Keyboard#History

2: http://www.asktog.com/columns/082iPad&Mac.html