Acer TM7100 Series Service Manual page 111

Table 2-6 NS87338VJG Pin Descriptions
Pin No.
/CTS1, 72, 64
/CTS2
D7-D0 10-17
/DACK0 53,
/DACK1 52,
/DACK2 3
/DACK3 49
/DCD1, /DCD2 75, 67
DENSEL 46
(Normal Mode)
DENSEL 76
(PPM Mode)
/DIR 39
(Normal Mode)
/DIR 78
(PPM Mode)
/DR0, 42, 43
/DR1
(Normal Mode)
I/O Description
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.
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) 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, 3. 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.
DACK3 is multiplexed with DRATE1, MSEN1, /CS0 and SIRQI2.
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.
O
FDC Density Select. DENSEL indicates that a high FDC density data
rate (500 Kbs, 1 Mbs or 2 Mbs) or a low density data rate (250 or 300
Kbs) is selected. DENSEL is active high for high density (5.25-inch
drives) when IDENT is high, and active low for high density (3.5-inch
drives) when IDENT is low. DENSEL is also programmable via the
Mode command.
O
FDC Density Select.
signal in PPM Mode when PNF=0.
O
FDC Direction. This output determines the direction of the floppy disk
drive (FDD) head movement (active = step-in; inactive = step-out)
during a seek operation. During reads or writes, DIR is inactive.
O
FDC Direction. This pin offers an additional Direction signal in PPM
Mode when PNF = 0.
O
FDC Drive Select 0, 1. These are the decoded drive select outputs
that are controlled by Digital Output Register bits D0, D1. The Drive
Select outputs are gated with DOR bits 4-7. These are active low
outputs. They are encoded with information to control four FDDs
when bit 4 of the Function Enable Register (FER) is set.
exchanges logical drive values with DR1 when bit 4 of Function
Control Register is set.
The CPU tests the condition of this /CTS signal by
When low, this indicates that the
This pin offers an additional Density Select
DR0