If you have read the Steve Jobs biography by Walter Isaacson, you would already know that Apple started working on a tablet computer before the iPhone was made. Steve Jobs also admitted to Walt Mossberg that when he saw what his UI guys came up with on the tablet, he saw the opportunity to shift the touch interface to a phone and ordered the teams to focus on the iPhone first:
“I’ll tell you a secret. It began with the tablet. I had this idea about having a glass display, a multitouch display you could type on with your fingers. I asked our people about it. And six months later, they came back with this amazing display. And I gave it to one of our really brilliant UI guys. He got [rubber band] scrolling working and some other things, and I thought, ‘my God, we can build a phone with this!’ So we put the tablet aside, and we went to work on the iPhone”
But recent court filings which included depositions by Jony Ive have uncovered some engineering samples of some of the first tablet machines which would later take shape as the iPad. This tablet originates between 2001 and 2004, which just goes to show how many years of development go into any new product at Apple (makes a person wonder what they are busy with for 2020?). The tablet is a lot thicker than the original iPad of course, and it is made from plastic, which is consistent with Apple’s design language at the time (think iMac G4 and later).
Here are some more pictures: