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Output Signals

Data

Terminal

Ready

(DTR),

33: When low, informs the

MODEM

or data set that the INS8250 is ready to communicate. The

DTR

output signal can be set to an active low by programming Bit 0

(DTR) of the

MODEM

Control Register to a high level. The

DTR

signal

set high upon a Master Reset operation.

Request

Send(RTS),

32: When low, informs the

MODEM

data set that the

INS8250

ready to transmit data. the RTS output

signal can be set to an active low by programming Bit 1 (RTS) of the

MODEM

Control Register. The RTS signal

set high upon a Master

Reset operation.

Output

(OUT

1),

34: User-designated output that can be set to

an active low by programming Bit 2

(OUT

the

MODEM

Control

OUT

1 signal

set high upon a Master

Reset operation.

Output

(OUT

2),

31: User-designated output that can be set

to an active low by programming Bit 3

(OUT

2) of the

MODEM

Control Register to a high level. The

OUT

2 signal is set high upon a

Master Reset operation.

Chip

Select

Out

(CSOUT),

24: When high, indicates that the

chip has been selected by active

CSO,

CSl,

and

CS2

inputs.

data

transfer can be initiated until the

CSOUT

signal

a logic

Driver

Disable

(DDIS),

23: Goes low whenever the

CPU

reading data from the INS8250. A high-level

DDIS

output can be

used to disable an external transceiver (if used between the

CPU

and

INS8250 on the D7-DO

Data

Bus) at all times, except when the

CPU

reading data.

Baud

Out

(BAUDOUT),

15: 16x clock signal for the transmitter

section of the INS8250. The clock rate is equal to the main reference

oscillator frequency divided by the specified divisor in the Baud

Generator Divisor Latches. The

BAUDOUT

may also be used for the

receiver section by typing this output to the

RCLK

input

the chip.

Interrupt

(INTRPT),

30: Goes high whenever

anyone

of the

following interrupt types has an active high condition and

enabled via

the IER: Receiver Error Flag; Received

Data

Available; Transmitter

Holding Register Empty; and

MODEM

Status. The

INTRPT

Signal is

reset low upon the appropriate interrupt service or a Master Reset

operation.

Serial

Output

(SOUT),

11: Composite serial data output to the

communications link (peripheral,

MODEM

or data set). The

SOUT

signal

set to the Marking (Logic

state upon a Master Reset

operation.

2-132

Brand	IBM
Model	5150
Category	Desktop
Language	English

IBM 5150 Hardware Reference Manual

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