The first two iPod models had a 6-pin FireWire port. It wasn't until the third generation that they introduced the 30-pin connector that worked with both FireWire and USB on the PC side to introduce Windows compatibility.
And then they changed the spec on the 31 pin connector half way through it's life. I had an iPod ready car stereo back in the day, and it required an adapter to use my iPhone even though they were both the same physical connector. Fuckin stereo was expensive back then especially one with iPod integration. I had the thing for maybe 2 years at the most. Felt pretty burned by that one.
The first two iPod models had a 6-pin FireWire port. It wasn't until the third generation that they introduced the 30-pin connector that worked with both FireWire and USB on the PC side to introduce Windows compatibility.