• When
the
reset switch
is
pressed together with the I CTRL I key, addresses $0000
to
$0FFF
and
from
$DOOO
to
$FFFF
are assigned to
RAM
.
• When
the
# command
is
entered after
the
reset switch has been pressed, the computer operates in
the
same manner
as
after
the
reset switch has been pressed together with the I CTRL I key.
4.2.5 Bank switching
a) Memory blocks can be selected
by
outputting
data
to
I/0
ports
as
shown below.
SWITCHING
1/0
PORT
$0000"'$0FFF
$D000"'$FFFF
$EO
SYSTEM AREA (D-RAM)
------
$El
--------
SYSTEM AREA (D-RAM)
$E2
MONITOR (ROM)
----
$ E3
-----
V-RAM, KEY, TIMER
$
E4
MONITOR (ROM) V-
RAM
, KEY, TIMER
$ E5
----
Inhibit
~
Return
to the front
of
$E6
condition, where being
inhibitted
by
$
ES
.
Note:
Outputting
data
to
I/0
port
$
E4
performs
the
same function
as
pressing the reset switch.
b) Examples:
OUT ($EO), A
Assigns addresses
$0000 to
$0FFF
to RAM,
but
does
not
change execution address. The contents
of
variable A do
not
affect the result.
OUT ($E4), A
Initializes memory to
the
state immediately after the power has been turned on.
Note:
Since
the
program counter is
not
moved
by
the OUT statement, care must be taken when switch-
ing memory blocks
if
the program
counter
is located in the area from $0000
to
$
0FFF
or
from
$DOOO
to
$
FFFF.
------------------
--
---------------------------------------------------
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