Yesterday I found a Twentieth Anniversary Mac in my Nonna's basement. Apparently it's been there since 2002. I was very curious about this and I Googled it and found that it was a special edition.
On the rear and side are some ports I'm not familiar with. I wonder if anyone can explain them?
The rear has 6 ports and I don't know what ports 3, 4, and 5 are for? There's also a large port on the left hand side that I'm not familiar with.
Can anyone help?
Wow, that's a find!
Actually, there are more than six ports on the rear, there's also a cover you can open to reveal a whole heap of other ports (e.g. Serial ports, ADB port, etc).
However, to explain the ports in your question:
Below are some images I've taken from the Twentieth Anniversary Mac Service Source:
IMPORTANT NOTE
This model actually has a switch to select the appropriate voltage for your country (see below), so make sure you have the correct voltage selected for your location.
If your location is not listed, then select whichever is appropriate (e.g. if you're in Australia then select 230v).
[EDIT]
Finally, as per IconDaemon's comment below, you can access the service documentation directly for yourself.