Lance Carnes of Personal Tex Inc, 12 Madrona Ave, Mill Valley, CA94941
(415-388-8853) ported Donald Knuth's TeX software to the HP3000 in 84 (if
memory serves me correctly). I certainly ran it successfully at
Sheffield University about that time.
I don't know that Lance still has the HP3000 version as most of his
effort goes into his (superb) Windows PC version of TeX. He can be
contacted a [log in to unmask]
The TeX community has various sites on the web, most of which will have
the source in "C" code so you could create your own HP3000 version if you
really wanted to and had a compiler.