Sharp MZ-800 - Page 150

(2) I/O port address
The following 1/O port addresses are already assigned to the existing I/O devices or are reserved
for peripheral devices which Sharp has planned for the future.
BO to B3 : Serial 1/O port Fe FV som
CC to CF : GDG (graphic display generator) a ma
DO to D3 : 8255 (data recorder and keyboard control) :
D4 to D7 : 8253 (programmable interval timer) : ‘ Av
D8 to DF : FDC (floppy disk controller)
E0 to E6 : GDG »
FO to Fl: Joystick inputs
F2 : PSG output
F4 to F7 : QDC
FC to FF : Z-80A PIO (printer)
(3) Programmable clock generator (8253) 146
The MZ-800 has a built-in programmable interval timer. This timer is used for controlling the built-in
clock and programmable sound generator.
In
the
MZ-700
mode,
memory
mapped
I/O
addresses
$E004
to
$E007
are
assigned
to
this
timer,
while
in
the
MZ-800
mode,
I/O
mapped
addresses
$D4
to
$D7
are
assigned.
$D4 : counter 0 f .
$D5: counter 1 © yr t
$D6 : counter 2 pa (eT
$D7 : control word register
Counter 0 is used for the programmable sound generator, counter 1 is used internally and coun-
ter 2 is used for interrupting the CPU.
a
PC2
DO~D7 cpu
INT
AO, At — > vor
—< 1.1MHz
8253