Date   : Sat, 11 Feb 1984 08:01:11 EST
From   : Charlie Strom (NYU) <strom@brl-bmd>
Subject: SETDRU

Another solution to the problem of multiple overlays is a program called
SETDRU, authored by Mike Rubenstein. SETDRU is a BDOS filter which allows
remapping of up to 8 file specifications (unambiguous or ambiguous)
so that a program can access any other files on any drive/user. This
works very well with Wordstar, and allows me to have a small (<1K)
program called EDIT.COM on my ZCPR2 root du. Invoking EDIT will call
Wordstar which could be on any other du as well as its overlays which
could be on the same or yet another du. If ZCPR is not installed, one
must have multiple copies of EDIT.COM, but not of WS or its overlays.

SETDRU actually consists of a user interface and two filters, one
that allows the filter to be bound to the .COM program of
interest and another which calls the program. The latter is required
for programs such as WS that test its integrity after re-entry from the
R command.

SETDRU is in Z80 code. I will be completing an 8080 conversion in a
few days and will upload relevant files to Simtel at that time and will
post a notice to the list. I have run this program successfully under
CP/M Plus as well as 2.2.