Sharp PC-4741 Service Manual page 63

Ring Indicator a-RI, pin-39)
ow
0
th' line indicates that rin is detected b the modem or data
set. For FIT is a modem control input, its state can e as e
y
referring to the bit 6 (RI) of the modem status register. The bit 2
(TERI)
of
the modem status register is set 1 when there was a
change in the state of the
m
input in the period that this register is
read after the modem status register was read.
NOTE: An interrupt is caused when the modem starus interrupt is
enabled and that there was a change in the AI bit of the
modem status register.
VCC: pin-40
+5V supply
VSS:pin-20
GND (OV), reference voltage ground
OUTPUT SIGNAL DESCRIPTION
Data terminal ready (DTR, pin-33)
A Iowan this line indicates that the ACE is enabled to communicate
with the modem or the data set.
I5iR
turns active when the bit 0
(OTR) of the modem control register is set by the program. This
output is set high level after the master reset is conducted. During the
loopback mode, the signal is held high level.
Request to send (RTS, pin-32)
A low on this line indicates that the ACE is enabled to send data to
the modem or the data set.
fi'l'13
turns active when the bit 1 (RTS) of
the modem control register is set
by
the program. This output is set
high level after the master reset is conducted. During the loopback
mode, the signal is held high level.
Output-l (OUT1, pin-34)
A general purpose output line which goes active low when the bit
2
(OUT1) of the modem control register is set by the program.
mrrr
is
set high level after the master reset is conducted. During the loop-
back mode, the signal is held high level.
Output-2 (OUT2, pin-3l)
A general purpose output line which goes active low when the bit 3
(OUT2) of the modem control register is set by the program.
LmT2
is
set high level after the master reset is conducted. During the loop-
back mode, the signal is held high level.
Chip select out (CSOUT, pin-24)
A high level signal is issued on this line when CSO, CS1, and
"SC2
are
set high to select chip. Data are not sent out until CSOUT goes high.
Driver select out (DDIS, pin-23)
Goes low when ACE data are read by the CPU. When the CPU is
reading other than data, the line is kept high. Used to disable an
external data transceiver which is established on the data bus D7 -
DO between the CPU and the ACE.
Baud out (BAUDOUT, pin-15)
The 16 x clock used in the ACE transmitter circuitry is sent out. The
clock frequency is the value the basic clock input is divided by the
value set in the baud rate divisor latch. When the BAUDOUT output is
connected to the RCLK input, it can also be used for the receiver
clock.
Interrupt (INTRPT, pin-3D)
Goes active when one of receiver error flag, receive data available,
transmitter holding register empty, and modem status interrupts is
requested. If the corresponding IER bit was set, the line goes high.
The INTR output is reset low after the master reset is conducted or
an adequate interrupt service is done.
Serial output (SOUT, pin-ll)
Through this line is sent out the serial data to the communication link
(modem or data set). The line is set high (MARK) when the master
reset is conducted.
-61-
-
P 0-4741
INPUT/OUTPUT PIN DESCRIPTION
An eight line tri-state inpuUoutput used to carry bidrection ata com-
munication between the ACE and the CPU. Data. control word, and
status information are transferred via this data bus.
External clock Input/output (XT ALl, XT Al2, pln-16 and
17)
Connected to the basic clock input (crystal oscillator or external
clock).
NOTE: Pin numbers described are for the dual in-line package.
Pin Configuration
os
7
D. 8
D7 9
RCLK 10
SIN 11
NO 12-
sour
13
eso
14
CS1 15
eS2 16
~17
PLCC package
NS16450
INS82C50A
~
§
I~ ~ ~ ~ I~ ~
x
Top
view
39 MR
38 (5iJfi"
"
"'"
36
RfS
35
0iJ'i'2
34 NC
33 INTER
32 NO
31 AO
SO A1
29 A2