The format came out around 1970 and I think all the biggies of the day had their own versions. Ampex was probably first by a hair in that they were the biggest tape supplier to the industry and were machine manufactures as well so odds are that if they had plans to slit 2" tape, they had a machine that could record on it too.
MCI, EMI, Ampex, Studer, Scully, & 3M were all early adopters of the format. Otari didn't offer a competitive model until the early 80's and TASCAM was the last one to make an initial model in the late 80's.
Interestingly though, 16 channel two inch machines came first before their 24 track cousins and for a very short time, 3M produced a 3 inch, 32 track machine but ran into too many mechanical problems as the reel motors, guides and heads were stressed to a far greater degree then they originally imagined and the format died a quick death.
Studer is the last remaining manufacturer to produce and sell 24 track, 2 inch machines and they are called the A827. Otari recently stopped production and has removed it from their product offering on their web-site.
I have an article called "50 years of magnetic recording" in one of my old Mix magazines and can dig it out when I have time to give more exacting dates and names. All the above writing is strictly from memory so don't flame me if I screwed up a date or two!
Cheers!