PC87332 datasheet(9/98 Pages) NSC

9 / 98 page

10 Pin Description (Continued)

TABLE 1-1 Pin Descriptions (Alphabetical)

Symbol

Function

A10–A0

21–31

Address

These microprocessor address lines determine which internal register is accessed A0 –

A10 are don’t cares during a DMA transfer

ACK

Acknowledge

This input is pulsed low by a connected printer to indicate that it has received data

from the parallel port This pin has a nominal 25 kX pull-up resistor attached to it (This pin is

shared with DR1 See Table 7-5 for further information)

AFD

Automatic Feed XT

When this signal is low the connected printer should automatically line feed

after each line is printed This pin is in a TRI-STATE condition 10 ns aftera0is loaded into the

corresponding Control Register bit The system should pull this pin high using a 47 kX resistor

(See DSTRB and Table 7-5 for further information)

AEN

Address Enable

This input disables function selection via A10 – A0 when it is high Access during

DMA transfer is NOT affected by this pin

ASTRB

Address Strobe

This signal is used in EPP mode as an address strobe It is active low (See

SLIN and Table 7-5 for further information)

BADDR01

55 58

Base Address

These bits determine one of four base addresses from which the Index and Data

Registers are offset (See Table 2-2) An internal pull-down resistor of 30 kX is present on this pin

Usea10kX resistor to pull this pin to VCC

BOUT12

73 65

BAUD Output

This multi-function pin provides the associated serial channel Baud Rate generator

output signal when test mode is selected in the Power and Test Configuration Register and the

DLAB bit (LCR7) is set After Master Reset this pin provides the SOUT function (See SOUT and

CFG0 – 4 for further information)

BUSY

Busy

This pin is set high by the printer when it cannot accept another character It has a nominal

25 kX pull-down resistor attached to it (See WAIT and Table 7-5 for further information)

CFG0 – 4

65 66 71

Configuration on Power-up

These CMOS inputs select 1 of 32 default configurations in which

the PC87334VLJPC87334VJG powers-up (See Table 2-1) An internal pull-down resistor of 30

73 74

kX is present on each pin Use a 10 kX resistor to pull these pins to VCC

CLK48

Clock 48

This pin is the CLK48 reset strap option During reset the value of this pin is latched into

bit 0 of TUP (CLK48 bit) A 30 kX internal pull-down resistor is present on this pin Use a 10 kX

resistor to pull it high during reset

CTS12

72 64

Clear to Send

When low this indicates that the MODEM or data set is ready to exchange data

The CTS signal is a MODEM status input whose condition the CPU can test by reading bit 4 (CTS)

of the MODEM Status Register (MSR) for the appropriate serial channel Bit 4 is the complement

of the CTS signal Bit 0 (DCTS) of the MSR indicates whether the CTS input has changed state

since the previous reading of the MSR CTS has no effect on the transmitter

Note

Whenever the DCTS bit of the MSR is set an interrupt is generated if MODEM Status interrupts are enabled

D7–D0

10–17

I O

Data

Bi-directional data lines to the microprocessor D0 is the LSB and D7 is the MSB These

signals all have 24 mA (sink) buffered outputs

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