MoM is correct, you can't find a copy of the original unix but there is possibly some (less than a klock of code and that is a very old estimate too) of the original unix source in BSD given the last count and most of it is in the Kernel. The closest you can get is FreeBSD or possibly System 7 (although I haven't looked into system 7 in a long time it is from the same lab and was designed as a replacement and can't vouch for how much of the source is still there).
The reason I say possibly is that there was a legal battle with AT&T / Bell about the giving away of the code and compiled binary's, this was at the dawn of the popular domestic ISP market and the uptake of Comp Sci as a good alternative to science or engineering and most students when in the lab wanted a unix box at home, When they saw the legal battle that was jeopardizing life of FreeBSD they chose Linux as a alternative and when they matriculated university and it was the dawn of the .com boom and they needed a few dosen servers on the cheep they used Linux over BSD as they had experience with it even though BSD offered stability and features that Linux either had but where unstable or just totally non existent, after that it was a toss up with SunOS (now Solaris, that was back then almost BSD with sun branding) or BSD.
I have for a time thought about trying to get as much of the old code as I can find (pre FreeBSD 4.0) code and a system that belongs in a museum and seeing what I can get out of it. Unix is the grand daddy of all serious unix systems out there and provides a stable platform that most commercial unix platforms and most of the open source hash jobs just can't hold a candle too.
