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PC87311A Datasheet(PDF) 10 Page - National Semiconductor (TI) |
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PC87311A Datasheet(HTML) 10 Page - National Semiconductor (TI) |
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10 / 78 page  10 Pin Description (Continued) Symbol Pin IO Function MFM 53 IO 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 O 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 IO 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 57 I 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 3I 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) PE 83 I 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 58 I Parallel Port Output Enable This pin is sensed during reset If it is low bit 7 of the Power and Test Register (PTR7) is set high and the parallel port will operate in the Extended Mode In this mode 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 RD 19 I Read Active low input to signal a data read by the microprocessor RDATA 35 I Read Data This input is the raw serial data read from the floppy disk drive RI12 70 62 I 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 O 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 I Serial Input This input receives composite serial data from the communications link (peripheral device MODEM or data set) SLCT 82 I 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 81 O 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 10 |
Similar Part No. - PC87311A |
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Similar Description - PC87311A |
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