-
MZ-5600
r=J
EJ I I I 1 1
11
1 1 I 1 1
ffi
I- I I I I
Fig.
115
(B)
Some keys are inoperative:
Checking key contacts
Connect
the
keyboard
to
the
System Unit, and
turn
on
the
system with
the
CTRL and ALG (a, c) keys depressed and
held. After making sure
all
the
indicators come on, press
the
keys
in
the
order shown by
the
arrows
in
the
above
figure.
If
no defective key
contact
exists,
all
the
indicators
will
go
off.
If
any defective
contact
exists,
all
the
indicators
will
remain on.
If
a wrong key
is
pressed and
the
indicators
come
on, they will
go
off
when
the
correct key
is
sub-
sequently pressed.
If
no
contact
trouble exists when all
the
keys have been
operated,
the
CAPS indicator will come on, indicating
that
the
key check was normal.
15-3
Key
search
timing
Bounce",
1.1\....'-
___
--'/
STROBE
SAMPLING
DATA
___
_
OUT
DATA
______
....I
n
..
_-'-:'
...
!-_2_bv-'-t_
..
_dat_.
_____
rL
Fig.
116
To prevent chattering and bounce,
the
same key
data
is
checked twice during each search, and only matching'key
data
is
regarded
as
correct. While
the
search cycle
is
5.5ms,
it
is
extended
to
16.5ms if a bounce occurs.
KEYl~
~'-------------
KEY'
_______
-'
STROBE
SAMPLING
DATAl
__
---'
DATA'
_______
---'I1...JULJlJLJUl ____________ _
OUT
DATA
__________
....JfLJl'-'.f
....
:
-'-f'
.....
·
----u;""~-;;-----
-
KEY2
DATA
Fig. 117
Key
search sequence for two-key operation
is
the
same
as
that
for single key operation_ When two keys are simul-
taneously
pressed, key data for
the
first and second keys
are successively transferred.
15-4
Eight-bit
keyboard processor J,tPD8OC49
Highlights
1)
Single-chip, 8-bit microprocessor.
2) Built-in 2K x 8 bit
ROM.
3) On-chip 128K x 8 bit
RAM.
4) Interruption service capability.
5) I/O port: 8 bits x 2
Data bus (serving
"Iso
as
I/O port): 8 bits x 1
-78-
6) Built-in clock generator.
7)
Single +2.5
to
+6V power supply.
Pin configuration
TO
Vcc
XTALl
Tt
XTALl:
P27
RESET
P26
ss
P25
INT
P24
EA
P17
Ri)
P16
PsEN
P15
WR
P14
ALE
PIa
DBO
P12
DBl
PH
DB2
PlO
DB3
VDD
DB4
PROG
DB5
P28
DB6
P22
DB7
P21
vss
20
21
P20
Fig.
118
Pin functions
Pl0-P17:
I/O
port
(port 1 )
P20-P27:
I/O
port
(port 2)
DBO-DB7:
Data bus
TO,
Tl:
Test
INT:
Interrupt
RD:
Read
WR:
Write
ALE.
Address latch enable
PSEN:
Program store enable
RESET: Reset
SS:
Single step
EA:
External access
XTAL1,2:
Quartz inputs
VDD:
Standby control
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