Duplex Multi-Environment Real-Time (DMERT) is a hybrid time-sharing/real-time operating system developed in the 1970s at Bell Labs Indian Hill location in Naperville, Illinois uses a 1978 snapshot of Bourne Shell "VERSION sys137 DATE 1978 Oct 12 22:39:57".
The Korn shell (ksh) written by David Korn based on the original Bourne Shell source code,[REF] was a middle road between the Bourne shell and the C shell.