Idris was an operating system developed by Whitesmiths. The C and Pascal compilers are included with the Idris operating system, as well as a lot of other "Unix like" programs and utilities.
Idris (operating system) - Wikipedia
I recently found some old diskettes with the CO-IDRIS operating system version 2.37 for PC/MS-DOS on IBM PC that I was running many years ago. I have created a virtual machine in VirtualBox running CO-IDRIS on MS-DOS from some very dusty old diskettes. The VirtualBox I am using runs on a Linux Mint machine, but I expect that it may also run under Windows.
I have made an image of CO-IDRIS with MS-DOS 6.22 running in QEMU.
I have also scanned parts of the comprehensive set of manuals that were shippped with the Idris operating system.