PC87311AVF datasheet(10/78 Pages) NSC

10 / 78 page

10 Pin Description (Continued)

Symbol

Function

MFM

During a chip reset when in PS2 mode (IDENT low) this pin is sampled to select the PS2 mode

(MFM high) or the Model 30 mode (MFM low) An internal pull-up or external pull-down 10 kX resistor

will select between the two PS2 modes When the PC-AT mode is desired (IDENT high) MFM should

be left pulled high internally MFM reflects the current data encoding format when RESET is inactive

MFM e high FM e low Defaults to low after a chip reset This signal can also be configured as the

PUMP data separator diagnostic output via the Mode command (see Section 426)

MTR01

46 43

Motor Select 01

These are the motor enable lines for drives 0 and 1 and are controlled by bits

D7 – D4 of the Digital Output register They are active low outputs They are encoded with information to

control four FDDs when bit 4 of the Function Enable Register (FER) is set (See DR01 and Table 2-4

for more information)

PD0 – 7

94 – 91

Parallel Port Data

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 DC Electrical

89–86

Characteristics)

PDIR

Parallel Port Direction

During reset the state of this pin determines the direction of the parallel port

data if the PTR7 e 0 The direction will be output (printer) when PDIR e 0 and PTR7 e 0 and it will be

input (scanner) when PDIR e 1 and PTR7 e 0 An internal pull-down resistor or 40 kX is on this pin

Usea10kX resistor to pull this pin to the required level during reset

PDWN

Power Down

This multi-function pin will stop the clocks andor the external crystal based on the

selections made in the Power and Test Register bits 1-2 (See CSOUT for additional information)

Paper End

This input is set high by the printer when it is out of paper This pin has a nominal 25 kX

pull-down resistor attached to it

POE

Parallel Port Output Enable

This pin is sensed during reset If it is low bit 7 of the Power and Test

software determines the direction of parallel port data via the parallel port Control Register (CTR5) If

this pin is high (PTR7 e 0) then the Compatible Mode is selected and the data direction is determined

by the state of PDIR pin at reset An internal pull-down resistor of 40 kX is on this pin Use a 10 kX

resistor to pull this pin to the required level during reset

Read

Active low input to signal a data read by the microprocessor

RDATA

Read Data

This input is the raw serial data read from the floppy disk drive

RI12

70 62

Ring Indicator

When low this indicates that a telephone ringing signal has been received by the

MODEM The RI signal is a MODEM status input whose condition the CPU can test 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 has changed from low to high since the

previous reading of the MSR

Note

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

RTS12

74 66

Request to Send

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

exchange data The RTS signal can be set to an active low by programming bit 1 (RTS) of the MODEM

Control Register to a high level A Master Reset operation sets this signal to its inactive (high) state In

the PC87312 loop mode operation holds this signal to its inactive state (See CFG0 – 4 for further

information) In the PC87311A loop mode operation holds this signal to its inactive state if the XTSEL

pin is high during reset If the XTSEL pin is low during reset the associated pin state is controlled by the

MCR1 bit during loop mode operation (See CFG0 – 4 for further information)

SIN12

75 67

Serial Input

This input receives composite serial data from the communications link (peripheral device

MODEM or data set)

SLCT

Select

This input is set high by the printer when it is selected This pin has a nominal 25 kX pull-down

resistor attached to it

SLIN

Select Input

When this signal is low it selects the printer This pin will be in a TRI-STATE condition

10 ns after a zero is loaded into the corresponding Control Register bit The system should pull this pin

high using a 47 kX resistor

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