Great quote from Steve Wozniak in Founders at Work:

So Mike was going to finance us, and then one day he said to me, “You have to leave Hewlett-Packard.” And I said, “Why? I designed two computers [Apple I and Apple II] and cassette tape interfaces and printer interfaces and serial ports and I wrote a Basic and all this application software, I wrote demos, and I did all this moonlighting, all in a year.”

He had been living and breathing hardware design since he was a kid, culminating in this breathtaking creative output.

Needless to say, he left HP to co-found Apple.