PC87338 datasheet(30/221 Pages) NSC

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Group 10

Power Down. This pin is used for the FDC Power-Down (PD)

output signal when bit 4 of PMC is 1. It is used for DR1 when bit 4

of PMC is 0. PD is active high whenever the FDC is put into a

power-down state by bit 6 of DSR (or bit 3 of FER, or bit 0 of PTR),

or by the MODE command.

PD is multiplexed with DR1.

PD0

PD1

PD2

PD3

PD4

PD5

PD6

PD7

I/O

Group 1

and

Group 11

Parallel- Port Data signals 0 through 7. These bidirectional pins

transfer data to and from the peripheral data bus and the parallel

port Data Register. These pins have high current drive capability.

See “Device Description” on page -197.

PD7-0 are multiplexed with INDEX, TRK0, WP, RDATA, DSKCHG,

MSEN0, DRATE0 and MSEN1, respectively. See Table 72 for more

information.

Group 2

Paper End. This parallel port input signal is set high by the external

printer when it is out of paper.

This pin is internally grounded by a nominal 25 K

Ω pull-down

resistor.

PE is multiplexed with WDATA. See Table 72 for more information.

PNF

Group 1

Printer Not Floppy. PNF is the Printer Not Floppy signal. It selects

the device which is connected to the PPM pins.

When a parallel printer is connected, PNF must be set to 1, and

when a floppy disk drive is connected, PNF must be set to 0. This

pin is configured as PNF when bits 7 and 6 of SIRQ3 are 10.

PNF is multiplexed with DRV2, DR23, SIRQI3 and IRSL2.

Group 1

Read. Active low input signal to indicate a data read by the

microprocessor.

RDATA

(Normal

Mode)

Group 4

Read Data. This input signal is the raw serial data read from the

floppy disk drive.

(PPM

Mode)

Group 4

Read Data. This pin provides an additional read data signal in PPM

mode when PNF = 0.

RDATA is multiplexed with PD3. See Table 72 for more information.

RI1

RI2

Group 1

Ring Indicators 1 and 2. When low, these UART signals indicates

that a telephone ring signal has been received by the appropriate

modem.

The RI signal is a modem status input signal whose condition can

be tested by reading bit 6 (RI) of the Modem Status Register (MSR)

for the appropriate serial channel. Bit 6 is the complement of the RI

signal. Bit 2 (TERI) of the MSR indicates whether the RI input

signal has changed from low to high since the previous reading of

the MSR.

When the TERI bit of MSR is set to 1, an interrupt is generated if

modem status interrupts are enabled.

RI2 is multiplexed with A11. When RI2 is not selected, it is masked

to 1.

Symbol

PQFP

TQFP

I/O and

Group #

Function

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