Radio Shack TRS-80 Owner's Manual page 57

;
(Increment Display Address)
If
the
Display
is
half-screen, the
first
location
shown
is
incremented by 16
when
you press CD-
If
the full-screen
format
is
displayed,
the starting
address will
be
incremented by
256.
—
(Decrement Display Address)
If
the
Display
is
half-screen, the
first
location
is
decremented by
16
when
you
press
(ED. If
the full-screen
format
is
displayed,
the starting
address
will
be
decremented by 256.
J
(Jump)
Press
GD
to
transfer control to a
machine-language program,
setting optional
breakpoints.
Debug
will
respond with
the
prompt: J
ADDRESS?
=
You
may
type
in a
jump
address
and
a
breakpoint address.
The
command
is
terminated
when you
press (ENTER)
.
Type
in
the
addresses
in
one
of three
formats:
j
address?
-
aaaa,bbbb\MfW
j
address?
=
aaaa
iMTlFP
j
address?
=
,bbbb(&tTM
aaaa
is
a four-digit
hexadecimal address specifying the
jump
destination.
If
omitted, the
address
in
the pc register
is
used
bbbb
is
a four-digit
hexadecimal address specifying
a
breakpoint.
Before the
Computer
executes an instruction at this
address,
it
will
return control
to
debug.
If
this
address
Is
omitted, control
will
not return to
debug.
Notes: Breakpoints
must
be
set at
the
beginning of z-80 instructions.
You
may
not set
breakpoints
in
rom
addresses.
The breakpointed address
will
contain an
X'F7' until
the
breakpoint
is
encountered.
Then
the original contents will
be
restored
and
debug
will
take control again.
Q
(Quit)
Pressing
©
turns off
debug
and returns control
to
trsdos.
41