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Commodore Plus 4 - Page 243

Commodore Plus 4
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P2A.6
PSA7
F&A8
78
9A
D8
SEI
TXS
OLD
anguage
Monitor
Commands
231
The
monitor
is
asked
to
disassemble
the
contents
of
ROM
locations
$F2A4
through
$F2A8
inclusive.
It
displays
the
contents
in
hexadecimal
and
in
mne
monic
opcodes
and
operands.
Pilling
Memory
with
a
Specified
Byte—The
F
Command
The
F
(Fill)
command
is
used
to
insert
a
single
specified
data
byte
into
every
location
of
a
section
of
memory.
The
syntax
is
as
follows:
P
start
address
end
address
data
byte
The
start
address
is
the
hexadecimal
address
at
which
the
section
of
memory
begins.
The
end
address
is
the
last
hexadecimal
address
of
the
section
of
memory.
The
data
byte
is
the
hexadecimal
number
(one
or
two
digits)
to
be
inserted
into
each
memory
location.
Every
location
from
the
starting
address
through
the
ending
address
is
set
equal
to
the
specified
data
byte.
If
you
attempt
to
alter
ROM
locations
in
this
way,
the
RAM
under
the
ROM
is
filled
with
the
specified
data
byte.
Example:
P
3000 3004
PF
The
monitor
is
asked
to
insert
the
value
$FF
into
every
memory
location
from
$3000
to
$3004
inclusive.
Executing
a
Program—The
G
Command
The
G
(Go)
command
is
used
to
begin
execution
of a
machine
code program.
The
syntax
is
as
follows:
G
address
The
address
is
the
optional
hexadecimal
address
at
which
the
execution
begins.
The
monitor
begins
executing
instructions
at
the
address
specified.
If
no
address
is
specified,
execution
begins
at
the
current
value
of
the
program
counter.
To
view
the
current
value
of
the
program
counter,
use
the
R
command.
To
return
to
the
monitor
after
execution,
the
machine
language
program
must
end
with
a
BRK
instruction.
The
value
of
the
program
counter
following
the
execution
of
a
BRK
instruction
is
not
necessarily
the
address
of
the
instruction
following
the
BRK.
Care
must
be taken
when
you
do
not
specify
the
starting
address.

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