MINIX (from mini-Unix) is a Unix-like operating system based on a microkernel architecture. Since version 2.0, it has been Portable Operating System Interface (POSIX) compliant.
Early versions of MINIX were created by Andrew S. Tanenbaum for educational purposes. Starting with MINIX 3, the primary aim of development shifted from education to the creation of a highly reliable and self-healing microkernel OS. MINIX 3 was developed as open-source software.
MINIX was first released in 1987, with its complete source code made available to universities for study in courses and research. It has been free and open-source software since it was relicensed under the BSD-3-Clause license in April 2000.
Andrew S. Tanenbaum created MINIX at Vrije Universiteit in Amsterdam to exemplify the principles conveyed in his textbook, Operating Systems: Design and Implementation (1987). (Despite sharing a name, it has no relation to the older MINIX from Digital Systems House, Inc. based on AT&T Unix code.)
An abridged 12,010 lines of the C source code of the kernel, memory manager, and of MINIX 1.0 are printed in the book. Prentice-Hall also released MINIX source code and binaries on floppy disk with a reference manual. MINIX 1 was system-call compatible with Seventh Edition Unix.
Tanenbaum originally developed MINIX for compatibility with the IBM PC and IBM PC/AT 8088 microcomputers available at the time.
MINIX 1.5, released in 1991, included support for MicroChannel IBM PS/2 systems and was also ported to the Motorola 68000 and SPARC architectures, supporting the Atari ST, Amiga, Macintosh and Sun SPARCstation computer platforms. There were also unofficial ports to Intel 386 PC compatibles (in 32-bit protected mode), National Semiconductor NS32532, ARM and Inmos transputer processors. Meiko Scientific used an early version of MINIX as the basis for the MeikOS operating system for its transputer-based Computing Surface parallel computers. A version of MINIX running as a user process under SunOS and Solaris was also available, a simulator named SMX (operating system) or just SMX for short.