The ACK's notability stems from the fact that in the early 1980s it was one of the first portable compilation systems designed to support multiple source languages and target platforms. The ACK was known as
MINIX's native compiler toolchain until the MINIX
userland was largely replaced by that of
NetBSD (MINIX 3.2.0) and
Clang was adopted as the system compiler. It was originally closed-source software, initially distributed by Tanenbaum himself, later through UniPress Software and Transmediair Utrecht as distributors in the Americas and Europe respectively. The distribution of compiler
binaries for MINIX was a special case in this arrangement. In April 2003, it was released under the
BSD licenses. ==Working principle==