HI-TECH Software
(HI-TECH Australia),
maker of HI-TECH C and C crosscompilers, released its Pacific
C Compiler as freeware! (Be sure to get pacc.exe if you want a
commandline interface.) I used to have some direct links to the
Pacific C pages, but they've reorganized their site— start
at the Downloads pulldown on the homepage. You have to register
now too. Pacific C and other compilers may also be found at
the FreeDOS Project.
Turbo C (along with Turbo Pascal) is freeware now, but Borland
is one of those places that likes to muck around frequently with
its directory structure, resulting in rapid link rot. So the most
robust method for locating Turbo C is probably use of the search
engine of your choice.