the bite in the Apple logo is to fit in the apple letter next to the logo. The little a fills the bite gap.
I have owned Apple II since 1978 and in those days the Apple logo always come with the letter apple next to the logo. It is only later when only the Apple logo stand on its own.
補充內容 (2015-9-13 15:14):
I stop buying real iMac. The last one I bought was Mac IIsi, and later had a PowerMac first generation.