Re: legacy machine MSDOS pdftex standalone

If all you need is the binary, there are old pdftex.exe's on CTAN:

mirrors.ctan.org/obsolete/systems/msdos/pdftex/pdftex.exe
mirrors.ctan.org/systems/msdos/djgpp-contrib/pdftex-djgpp/pdftex.exe

They are part of whole distributions, so if you need more, maybe one of
them will suffice.

Good luck,
Karl