ISIS

ISIS is an operating system, created by Intel for their Intel Microprocessor Development System around 1976[1] and adopted as ISIS-II for systems with floppy drives. User interface is Unix-like, even from the program interface point of view, communication with the kernel is this way (i.e., for file opening program should send the name of file and gets back a handle). On the diskette, there was no subdirectory; instead of this, each device has its name, which can be written between a pair of colons (:F0: and :F1: were floppies, :LP: was printer, etc.).