PC97338VLJ datasheet(25/221 Pages) NSC

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DCD1

DCD2

Group 1

UART Data Carrier Detect signals 1 and 2. When low, this signal

indicates that the modem or data transfer device has detected the

data carrier.

The DCD2,1 signals are modem status input signals whose

condition can be tested by reading bit 7 (DCD) of the Modem

Status Register (MSR) for the appropriate serial channel. Bit 7 is

the complement of the DCD signal. Bit 3 (DDCD) of the MSR

indicates whether the DCD input signal has changed state since the

previous reading of the MSR.

If modem status interrupts are enabled, an interrupt is generated

whenever the DDCD bit of the MSR is set to 1.

DCD2 is multiplexed with A15. When DCD2 is not selected, it is

masked to 1.

DENSEL

(Normal

Mode)

Group 10

Density Select. Indicates that a high density FDC data rate (500

Kbps, 1 Mbps or 2 Mbps) or a low density data rate (250 Kbps or

300 Kbps) is selected. The polarity of DENSEL is controlled via bit

6 of the ASC register. The default is active high for high density.

DENSEL is also programmable via the MODE command.

DENSEL is multiplexed with ADRATE1.

(PPM

Mode)

Group 10

Density Select. This pin provides an additional Density Select

signal in PPM mode when PNF = 0.

DENSEL is multiplexed with AFD, DSTRB. See Table 72 for more

information.

DIR

(Normal

Mode)

Group 10

Direction. This FDC output signal determines the direction of the

Floppy Disk Drive (FDD) head movement (active = step in, inactive

= step out) during a seek operation. During read or write

operations, DIR is inactive.

(PPM

Mode)

Group 10

Direction. This FDC pin provides an additional direction signal in

PPM Mode when PNF = 0. DIR is multiplexed with INIT. See Table

72 for more information.

DR0

DR1

(Normal

Mode)

Group 10

FDC Drive Select signals 0 and 1. These FDC signals are

decoded drive select output signals controlled by Digital Output

These signals are gated with DOR bits 7 through 4. These are

active low output signals. They are encoded with information to

control four FDDs when bit 4 of the Function Enable Register (FER)

is set. DR0,1 are exchanged only via the TDR register. (Bit 4 of the

FCR register is reserved.)

DR1 is multiplexed with PD.

DR1

(PPM

Mode)

Group 10

FDC Drive Select 1. This signal provides an additional drive select

signal in PPM mode when PNF = 0. It is drive select 1 when bit 4

of FCR is 0. It is drive select 0 when bit 4 of FCR is 1. This signal

is active low. DR1 is multiplexed with ACK. See Table 72 for more

information.

DR23

Group 10

Drive 2 or 3. This FDC signal is asserted when either drive 2 or

drive 3 is accessed (except during logical drive exchange, see bit 3

of TDR). This pin is configured when bits 7, 6 of SIRQ3 are 01.

DR23 is multiplexed with IRSL0, DRV2, SIRQI3 and PNF.

Symbol

PQFP

TQFP

I/O and

Group #

Function

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