[6SJ7]

The first was the 2001 USB ibook. That is why they used the USB in the name because it was the first one.

First iBook introduced in 1999 had a single 1.1 USB port. The 2001 iBook was referred to as the 'duel USB' model because it was the first iBook with two USB ports.

[Petronski]

First iBook introduced in 1999 had a single 1.1 USB port. The 2001 iBook was referred to as the 'duel USB' model because it was the first iBook with two USB ports.

Apple only did this because (time-traveling) iPod users were complaining that their USB iPods couldn't work with their Macs. </sarc>