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Table 2-10
NS87336VLJ Pin Descriptions (continued)
Pin
No.
/CS0,
51, 3
/CS1
/CTS1,
72, 64
/CTS2
D7-D0
10-17
/DACK0
5,
/DACK1
54
/DACK2
55
/DCD1, /DCD2
77 69
I/O
Description
O
Programmable Chip Select. /CS0, 1 are programmable chip select
and/or latch enable and/or output enable signals that can be used as
game port, I/O expand, etc. The decoded address and the assertion
conditions are configured via the 87336VLJ's configuration registers.
I
UARTs 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. The CPU tests the condition of this /CTS signal by
reading bit 4 (CTS) of the Modem Status Register (MSR) for the
appropriate serial channel.
signal. Bit 0 (DCTS) has no effect on the transmitter.
/CTS2 is multiplexed with A13. When it is not selected, it is masked
to "0".
NOTE: Whenever the MSR DCTS bit is set, an interrupt is generated
if Modem Status interrupts are enabled.
I/O
Data. These are bidirectional data lines to the microprocessor. D0 is
the LSB and D7 is the MSB. These signals have a 24 mA (sink)
buffered outputs.
I
DMA Acknowledge 0, 1, 2. These active low inputs acknowledge
the DMA request and enable the /RD and /WR inputs during a DMA
transfer. It can be used by one of the following: FDC or Parallel Port.
If none of them uses this input pin, it is ignored. If the device which
uses on of this pins is disabled or configured with no DMA, this pin is
also ignored.
/DACK0, 1, 2should be held high during I/O accesses.
I
UARTs Data Carrier Detect.
modem or data set has detected the data carrier. The /DCD signal is
a modem status input. The CPU tests the condition of this /DCD
signal 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 DCD input
has changed state since the previous reading of the MSR.
NOTE: Whenever the MSR DDCD bit is set, an interrupt is generated
if Modem Status interrupts are enabled.
Bit 4 is the complement of the CTS
When low, this indicates that the
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