T3X is a small, portable, procedural, block-structured, recursive, almost typeless, and to some degree object-oriented language. Here are some of the more interesting parts of the T3X manual:
You can read the full text of the T3X Reference Manual here (but who wants to?). BTW, before you "wget" the manual: it is also contained in the below archive.
The architecture of the T3X compiler is described in detail in the book Lightweight Compiler Techniques.
The T3X compiler targets a virtual machine called the Tcode machine as well as the following native CPUs: 8086, 386, 21064 (Alpha). It runs on a variety of platforms, including: FreeBSD, NetBSD, Plan 9, Linux, and DOS. The compiler also includes a C backend.
On Unix systems, T3X needs an ANSI C (C89) compiler for bootstrapping. Once bootstrapped, it can compile itself.
T3X is no longer actively developed, but you can download a copy of the final version here:
t3x-817.tar.gz (2011-05-19, ~500KB)
The T3X compiler is now in the public domain.