Debug - Radio Shack TRS-80 Trsdos & Disk Basic Reference Manual

TRSDOS Commands
DEBUG
(real-time
debugging program)
DEBXJGiUpamm)]
where param =
ON
or
OFF,
and
ON
is
the default.
DEBUG
is
a real-time
debugging package
for
use with machine
language programs, including both foreground
tasks
and
back-
ground programs. (See Glossary.)
DEBUG
lets
you examine and
alter
the contents
of
the
Z-80
registers
and
RAM
locations;
jump
to specified addresses
and begin execution with optional
breakpoints; step
through programs one
instruction (or
one
CALL)
at a
time,
and more.
All
address
and byte
values in this
DEBUG
section are given
in
hexadecimal form
—
which
is
the
form
required
by
DEBUG.
DEBUG
loads into the overlay
area;
addresses
above
5
IFF
are
unaffected.
Type:
debug
Ezma
to
enable the
debugging
facility.
Normal
TRSDOS
command
interpretation continues; but the
debug program
is
now
set
to
load
and execute under any
of the following conditions:
1.
When
the
BREAK
key
is
pressed.
2.
After
a
program
is
loaded and
before
its first
instruction
is
executed.
3.
Upon
detection of
a disk-related
error.
Note:
TRSDOS
system
routines and execute-only
user routines
cannot be
fully
debugged: you can
use
DEBUG
to examine/alter
register
and
RAM
contents, but not
to single-step,
jump,
etc.,
when
these protected programs
are
the "targets"
for
DEBUG.
Furthermore,
since
DEBUG
loads into the overlay area
of
RAM,
you
can't use
it
with other
overlay
programs and
routines.
DEBUG
offers
two
display formats:
register
display
with
indirect
RAM
plus
any
64-byte
"page"
of
RAM;
full
screen,
256-byte page of
RAM.
4-3