The best public domain DVI to PostScript conversion program which runs under many operating systems is Tom Rokicki's dvips. dvips is written in C and ports easily to other operating systems; it is available as dviware/dvips
VMS versions are available through the DECUS library (see sources of software), and also from CTAN: systems/vms/Alpha/dvips555_axp_exe.zip (for Alpha-based machines), systems/vms/VAX/dvips555_vax_exe.zip (for VAX machines); support files are available in systems/vms/dvips555_support.zip, and a set of fonts for use with LaTeX2e are available in systems/vms/dvips_fontsupport.zip
A precompiled version for MS-DOS is available from systems/msdos/dviware/dvips
Karl Berry's version of dvips (called dvipsk) has a configure script and path searching code similar to that in his other programs (e.g., web2c); it is available from dviware/dvipsk
Another good portable program is dvitops by James Clark, which is also written in C and will compile under Unix, MS-DOS, VMS, and Primos; however, it does not support virtual fonts. It is available from dviware/dvitops
Macintosh users can use either the excellent drivers built into OzTeX or Textures, or a port of dvips in the CMacTeX package.