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2-84 Service Guide
Table 2-14 NS87336VJG Pin Descriptions (continued)
Pin No. I/O Description
/MSEN0
/MSEN1
(Normal Mode)
50, 49 I Media Sense. These pins are Media Sense input pins when bit 0 of
FCR is 0. Each pin has a 10 KΩ internal pull-up resistor. When bit 0
of FCR is 1, these pins are Data Rate output pins and the pull-up
resistors are disabled.
/MSEN0
/MSEN1
(PPM Mode)
86, 84 I Media Sense. These pins gives additional Media Sense signals for
PPM Mode and PNF = 0.
/MTR0
/MTR1
(Normal Mode)
44, 41 O FDC Motor Select 0, 1. 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. MTR0 exchanges logical motor values with MTR1 when bit 4
of FCR is set.
/MTR1
(PMM Mode)
82 O FDC Motor Select 1. This pin offers an additional Motor Select 1
signal in PPM mode when PNF = 0. This pin is the motor enable line
for drive 1 when bit 4 of FCR is 0. It is the motor enable line for drive
0 when bit 4 of FCR 1. This signal is active low
PD 43 O FDC Power Down. This pin is PD output when bit 4 of PMC is 1. It is
/DR1 when bit 4 of PMC is 0. PD is active high whenever the FDC is
in power-down state, either via bit 6 of the DSR (or bit 3 of FER, or bit
0 of PTR), or via the mode command.
PD0-7 92-89,
87-84
I/O 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.
PE 81 I Parallel Port Paper End. This input is set high by the printer when it
is out of paper. This pin has a nominal 25 KΩ pull-down resistor
attached to it.
PNF 47 I Printer Not Floppy. PNF is the Printer Not Floppy pin when bit 2 of
FCR is 1. It selects the device which is connected to the PPM pins.
A parallel printer is connected when PNF = 1 and a floppy disk drive
is connected when PNF = 0. This pin is the DRV2 input pin when bit
2 of FCR is 0.
/RD 17 I Read. Active low input to signal a data read by the microprocessor.
/RDATA
(Normal Mode)
33 I FDD Read Data. This input is the raw serial data read from the
floppy disk drive.
/RDATA
(PPM Mode)
89 I FDD Read Data. This pin supports an additional Read Data signal in
PPM Mode when PNF = 0.