Service manual
Pin
Symbol In/
Out
Active
Funetia
n
N
o.
lwe
i
,
....
,.
OATA1 - DATA8 In/Ou t
-
Bid
irectional perallel
dete
bul
fixed
to
the
outpUt mode.
Th
e inPl
II
mode
il
esteb
li
l hed with e high CDS
stete
.nd
the
ou
tput
mode
il
established with a low CDS
st.te.
Th
.
coflt.nu
of
date
are in
the
reverse
pha
se.
27
DSTB In/Out - Perallel
mode
deta
ItrObe
liinel.
Data
strobe
Is
sent when CDS il " 1
."
Data
strobe
il received when COS
is
"0."
28
ACK
In
/
Out
-
Parallel
mode
acknowledge Ilinel.
ACK
illllnt
when C
OS
is
"'."
ACK
is
received when CDS
II
"
0:
'
29
FAULT In /Ou l
-
Parallel
mode
fault Ilgnll.
When CDS i, " '
,"
Ihe co
nt
ents
of t he bit
"0"
of
Ihe
comman
d
byt
e ara IIInt ou
t.
When CDS il
"0,"
Ihe co
nle
nu
of
th
l,
,lgn,llIne
can be known by Ihe statUI b
it
"0."
Meinly used for
detection
of a
feultln
the device.
30
BUSY
In/Ou t
- Parellel
mode
bu,y
,ignll.
When CDS il " 1
,"
I
bu,y
,Ignal i
lllln
t.
When CDS
is
"0,"
I bu
sy
Ilgnllll
reclived.
31
PRIME I
n/Oul
-
Plrlllel
mode
inp
ut
PR
I
ME
lignl
l.
When CDS i, " 1
,"
illllrvn
n I lingle b
ll
Inp
ut
port
.
When CDS
is
"0
,"
il
serv.,
I' I single
tJil
OUtput line,
but
it
still
wo
uld
be
poui
ble
to
choose I high level
,low
level,
or
one-shot pulse sign,1.
32
SLCT In/Out
-
Plrallel
mode
select lignel.
When CDS
is
" 1
,"
the
co
nten
uof
the
bit
" 1" of Ihe
command
byleare
sent o
ut
.
Wh
en COS
is
"0,"
the
conten
tlof
thllslgnliline
Cln be known by
the
statUI bit " I
."
Ml
inly used for I device
II
lect.
33
RT'S
"",
Ser
il
l
mode
r&quest
to
..
nd
,Iinl
l.
A general purpose I·
bit
output
por
t In
th
e revers. phlSe.
By
programming
the
bit
"5"
of
Ihe co
mmlnd
byte
,
it
il sel
to
''0.
''
The
signal
il
normlily
used by Ihe modem
control IS I request
to
send.
34
=
'"
Serial m
ode
data
set ready ,ignel.
A general
purp
ose l· b
it
in
put
p
ort
in
the
rwer
se phase.
II
is
possible
to
know
the
state
of
th
l,ign
al
by
interrogetlng
thanlw,lnformatio
n (bit 7)
of
the
serial interlace. Th
is
signal
is
norml
ily used l
or
t
esu
by
the
modem
for such IS e
data
set
ready. With Ihe
PC,'600,
this ,Ignal
is
connected
with
th
e
AX
0 line.
35
CTS
'"
Ser
ia
l
mode
cleer
to
send signal.
Connected
to
GND.
If
tha
TXEN bit
of
th
a
comme
nd
byte
hIS been
$at
to
" 1
,"
a high
on
Ihis lina anables
the
SM
I
transm
it
(serial).
36
li'Ilf
"",
-
Serial
mode
date
terminal
re&dy
signal.
A general
purposel·blt
Inpu t
ponln
th
e
,werM
phase.
By
programming
the
bit
"5"
of
the
command
byte,
it
il
set
to
"0."
T
he
lignll
il
norm Illy used for
the
modem control
as a da
ta
terminal relldy.
37
TX D
"",
.
Serial
mode
transmit
datI
lig
neL
Serial
data
output
f
Of"
the
serial
inlerfact.
38
RXD
,"
-
Serial mode receive
data
lignel.
Serial
data
input
for the serIal Interface.
39
vee
P
ow'
r -
Power supply.
Rlpply
40
CDS
'"
-
Parall,l
mode
d irection selection lin,. Fixed
to
GND,
it',
,n
input s
ignello
determin'
the
direction
of
the
par,lIel
in
t,
rf~.
When
the
,ign,ll,
at I low
IlIVe
l,
the
par,lIel
interface i
loperlted
in
th
a
output
mode.
When Ihe signll il
81
I high
IlIVel,
the
par
l ilel
interface
i,
ope
rated
in
the
in
put
mod
e .
4'
XC
LK
,"
-
Fixed
to
GND.
This line
is
an
input
to
the
intern,
l 4-blt
pr
ogrammable prescaler. Its output"becomes
the
system
clOCk
(SYS-CLK) which II used for Inte
rn,l
timing generation end baud rate
generation.
Normally~
400KHz - 10M
Hz
II
uled
as Ih' Iystem clock frequency.
-
33
-