Go
Purpose:
Executes
the
program
currently
in memory.
Syntax:
G[
= address [addresses
II
Comments:
If
you
type
the
G
(go)
command
by
itself,
the
program
currently
in
memory
executes
as
if
it
had
run
outside
debug.
If
you
set
= address,
execution
of
the
G
command
begins at
the
address specified.
The
equal sign ( = ) is
required
so
that
debug
can
distinguish
the
start = address from
the
breakpoint
addresses.
With
the
other
optional addresses set,
execution
stops
at
the
first
address encountered, regardless
of
that address'
position
in
the
list
of
addresses that halt
execution
or
program branching.
When
pro-
gram
execution
reaches a breakpoint,
the
registers, flags,
and
decoded
instruction are displayed for
the
last
instruction
exe-
cuted.
(The
result is
the
same as
if
you
had
typed
the
R
(register)
command
for
the
breakpoint address.)
You may
set
up
to
ten breakpoints,
but
only at addresses contain-
ing
the
first byte
of
an
8086
opcode.
If
you
set
more
than
ten
breakpoints,
debug
returns
the
BP
error
message_
The
user
stack
pointer
must
be
valid and
must
have 6 bytes avail-
able for this command.
The
G
command
uses an IRET instruction
to
cause
a
jump
to
the
program
under
test.
The
user
stack
pointer
is set,
and
the
user flags,
Code
Segment register, and Instruction
Pointer
are
pushed
on
the
user
stack_
(If
the
user
stack is
not
valid
or
is
too
small,
the
operating system may
crash.)
An
interrupt
code
(OCCH) is placed at
the
specified
breakpoint
addressees).
When
debug
encounters
an
instruction
with
the
breakpoint
code,
it
restores
all breakpoint addresses
to
their original instructions.
If
you
don't
halt
execution
at
one
of
the
breakpoints,
the
interrupt
codes
are
not
replaced
with
the
original instructions.
Example:
Suppose
you
type the following command:
GCS:7550
Debug
2211
(G)o
USing the
Go
command
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