Idris (operating system)

Idris is an operating system released by Whitesmiths, of Westford, Massachusetts.

Written by P. J. Plauger, it was a real-time, Unix-like, multi-user, multi-tasking operating system. It was originally written for the PDP-11 and later ported to run on a number of platforms including VAX, Motorola 68000, System/370 and Intel 8086.

In 1986, seeking business customers for the Atari ST, Atari hired Computer Tools International to port Idris to the Atari ST.

Plauger started working on Idris in August 1978 and the product was commercially available from 1979 through 1988.

Idris was binary compatible with Version 6 Unix on PDP-11, but it could run on non-memory managed systems (like LSI 11 or PDP 11-23) as well. The kernel required 31 Kb of RAM, and the C compiler (provided along with the standard V6 toolset) had more or less the same size.

A specific version of Idris (CoIdris) was packaged as a .com file under MS-DOS and used it for low level I/O services. Idris was ported to the Mac by John O Brien (of Whitesmiths Australia) and remained available until the early 1990s.