4.3
Memory
Mapped
1/0
($EOOO-$E008)
Addresses
$EOOO
to
$E008 are assigned to
the
8255 programmable peripheral interface, 8253 pro-
grammable interval timer and
other
1/0
control ICs
so
that
various
1/0
devices (including music functions
using counter
#0
of
the 8253) can
be
accessed in
the
same manner
as
memory. The memory mapped
1/0
chart is shown below.
CPU
memory
address
Controller Operation
$EOOO
PA:
Output
$£001
,,
8255
Ps :
Input
$E002
Pc
:
Input
and
output
control
by
bit
setting
$E003
Mode control
$E004
C
0
:
Mode 3 (square wave rate generator)
$E005
8253
C
1
:
Mode 2 (rate generator)
$E006
C
2
:
Mode 0 (terminal counter)
$E007 Mode control
$E008
LS367, etc.
Tempo
, joystick and
HBLNK
input
130
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