Specifications

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PC/II+p Board Technical Reference Manual 66

For more detailed information about serial I/O, please refer to the Acer Laboratories M1543C datasheet,

found in section 2

, "Reference Documents" in this document.

7.23.1 Serial COM1 Pinout

Table 34 Signals – J904 – Serial COM1 Interface

PIN NAME PIN# SIGNAL NAME SIGNAL DESCRIPTION

C1-CTS#

a13 Clear to Send This active low input is the handshake signal which notifies the

UART that the modem is ready to receive data. The CPU can

monitor the status of C1-CTS# signal by reading bit 4 of Modem

Status Register (MSR). A C1-CTS# signal state change from low

to high after the last MSR read will set MSR bit 0 to a 1. If bit 3 of

Interrupt Enable Register is set, the interrupt is generated when

C1-CTS# changes state. The C1-CTS# signal has no effect on

the transmitter. Note : Bit 4 of MSR is the complement of C1-

CTS#.

C1-DCD#

a12 Data Carrier

Detect

This active low input is a handshake signal which notifies the

UART that carrier signal is detected by the modem. The CPU

can monitor the status of the C1-DCD# signal by reading bit 7 of

Modem Status Register (MSR). A C1-DCD# signal state change

from low to high after the last MSR read will set MSR bit 3 to a 1.

If bit 3 of Interrupt Enable Register is set, the interrupt is

generated when the C1-DCD# input changes state. Note : bit 7

of MSR is the complement of DCD.

C1-DSR#

e13 Data Set Ready This active low input is the handshake signal which notifies the

UART that the modem is ready to establish the communication

link. The CPU can monitor the status of the C1-DSR# signal by

reading bit5 of Modem Status Register (MSR). A C1-DSR#

signal state change from low to high after the last MSR read will

set MSR bit 1 to a 1. If bit 3 of Interrupt Enable Register is set,

the interrupt is generated when C1-DSR# changes state. Note:

Bit 5 of MSR is the complement of C1-DSR#.

C1-DTR#

e14 Data Terminal

Ready

This active low output is the handshake output signal that

signifies to modem that the UART is ready to establish data

communication link. This signal can be programmed by writing to

bit 0 of Modem Control Register (MCR).

C1-RI#

d14 Ring Indicator This active low input is the handshake signal which notifies the

UART that the telephone ring signal is detected by the modem.

The CPU can monitor the status of the C1-RI# signal by reading

bit 6 of Modem Status Register (MSR). A C1-RI# signal state

change from low to high after the last MSR read will set MSR bit

2 to a 1. If bit 3 of Interrupt Enable Register is set, the interrupt is

generated when the C1-RI# input changes state. Note : bit 6 of

MSR is the complement of C1-RI#.

C1-RTS#

c13 Request to Send This Active low output is the handshake output signal that

notifies the modem that the UART is ready to transmit data. This

signal can be programmed by writing to bit 1 of Modem Control

signal to inactive mode (high).

C1-RXD

d13 Receive Data Receive data serial input line.

C1-TXD

b13 Transmit Data Transmit data serial output line.