dbx can locate Fortran logical operators and print them.
To show logical operators in dbx:
demo% cat ShowLogical.f
LOGICAL a, b, y, z
a = .true.
b = .false.
y = .true.
z = .false.
END
demo% f95 -g ShowLogical.f
demo% dbx a.out
(dbx) list 1,9
1 LOGICAL a, b, y, z
2 a = .true.
3 b = .false.
4 y = .true.
5 z = .false.
6 END
(dbx) stop at 5
(2) stop at "ShowLogical.f":5
(dbx) run
Running: a.out
(process id 15394)
stopped in MAIN at line 5 in file "ShowLogical.f"
5 z = .false.
(dbx) whatis y
logical*4 y
(dbx) print a .or. y
a.OR.y = true
(dbx) assign z = a .or. y
(dbx) print z
z = true
(dbx) quit
demo%