The earliest version of the D-pad was on the Atari game brain(released in 1977). It had a set of four cross-oriented buttons with a symbol in the middle telling you that these buttons controlled direction.
Then came the Microvision by Milton Bradley from 1979.
The kind of D-pad that we're familiar now with on game controllers arrived in the 1980s with nintendo's games and watch platforms, it was also during this time the the term d-pad or +control pad was coined.
But now here's an interesting bit, did you know nintendo patented the d-pad? Here's an image from their patent
Now you might ask since nintendo patented the d-pad, how did other consoles' game controllers design managed not to get lawsuits from nintendo? Well, actually they did, but they've managed to exploit a loophole in nintendo's design. Look carefully at the following controllers...
Notice they either had a round base or wasn't linked together unlike nintendo's
Only dreamcast's controller was something similiar to nintendo's but they didn't get any lawsuit coming their way...Nintendo's patent actually expired in 2005, but now since analog sticks, motion sensing controllers or even no controllers(project natal) runs the rule, there's possibly no need for the d-pad to play major console games in the future...which is why i brought you this story today.