Author: Larry Davis, Washington University, St. Louis, Missouri

Submitted by: Robert Hassinger, Liberty Mutual Research Center, Hopkinton , Massachusetts

It is often desirable to check if a certain LINCtape unit is selected or write-enabled before doing some operation on it, in order that a message may be printed if not.

ISEL is a FORTRAN or SABR callable function which returns -1 if the unit specified is not selected, returns 0 if the unit specified is selected and not write-enabled, and returns 1 if the unit specified is selected and write-enabled.

Minimum Hardware: PS/8, OS/12, PDP-12 LINCtape

Other Programs Needed: PS/8 FORTRAN or PS/8 SABR

Source Language: SABR

Catalog: July 1974