just a question. i am using Attiny 45/85 using arduino as ISP, does this chip support one-wire library?
The one-wire library is implemented in software (not hardware). Thus it should work if the chip can keep up speed-wise. Judging by the data sheet the Tiny is a bit slower (like half speed) compared to the bigger models, but it might keep up.
If you are doing your own protocols you could probably adapt by just adjusting the timing in the inner loops at both ends.
You can run the 85 at 16MHz by using the internal PLL and it can also use and external Xtal (lose two pins) or oscillator (lose 1 pin).