Diagnose; A Versatile Trace Routine for the PDP-8 with EAE

Keith B. Oldham, North American Aviation Science Center,
Thousand Oaks, California

This trace routine will track down logical errors in a program
(the "sick" program). Starting at any convenient location in
the "sick" program, instructions are executed, one at a time,
and a record of all operations is printed out via the Teletype.
To avoid tracing proven subroutines, an option is provided to
omit subroutine tracing. The present routine is significantly
more versatile than two other trace routines in the DECUS
Library (DECUS Nos. 8-56 and 8-57) for the PDP-8 in that
it is able to trace "sick" programs containing floating point,
extended arithmetic and a variety of input/output instructions.
Diagnose is, however, at a disadvantage compared with
DECUS No. 8-56 in requiring more memory space (5 pages
as opposed to two); and compared with DECUS No. 8-57
in not possessing the trace-suppression features of the latter.
The mode of operation of Diagnose is quite different from the
other trace routines.

Minimum Hardware:
PDP-8 with EAE

Other Programs Needed:
Floating Point Package needed
for floating point tracing. (DEC-

Program is Relocatable

Catalog:November 1969