
1.0 Signal/Pin Connection and Description
(Continued)
Revision 1.2
23
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P
1.4.1
LPC Interface
1.4.2
ACCESS.bus (ACB) Interface (PC87413 and PC87417)
1.4.3
X-Bus Extension (PC87416 and PC87417)
Signal
Pin(s)
I/O
Buffer Type Power Well
Description
LAD3-0
1
1. This pin is neither 5-Volt tolerant, nor back-drive protected.
110-113 I/O
IN
PCI
/O
PCI
V
DD
LPC Address-Data.
Multiplexed command, address bidirectional
data and cycle status.
LCLK
1
114
I
IN
PCI
V
DD
LPC Clock.
Derived from the PCI clock (up to 33 MHz).
LFRAME
1
117
I
IN
PCI
V
DD
LPC Frame.
Low pulse indicates the beginning of a new LPC cy-
cle or termination of a broken cycle.
LDRQ
1
118
O
O
PCI
V
DD
LPC DMA Request.
Encoded DMA request for LPC Interface.
LRESET
1
120
I
IN
PCI
V
DD
LPC Reset.
Derived from the PCI system reset.
SERIRQ
1
119
I/O
IN
PCI
/O
PCI
V
DD
Serial IRQ.
The interrupt requests are serialized over a single pin,
where each IRQ level is delivered during a designated time slot.
CLKRUN
1
124
I/OD IN
PCI
/OD
6
V
DD
Clock Run.
Indicates that LCLK is going to be stopped and re-
quests full-speed LCLK (same behavior as PCI CLKRUN).
Signal
Pin(s)
I/O
Buffer Type Power Well
Description
ACBCLK
47
I/O
IN
SM
/OD
6
V
SB
ACCESS.bus Clock.
An internal pull-up for this pin is optional.
ACBDAT
46
I/O
IN
SM
/OD
6
V
SB
ACCESS.bus Serial Data.
An internal pull-up for this pin is
optional.
Signal
Pin/s
I/O Buffer Type Power Well
Description
XRD_XEN
14
O
O
3/6
V
SB
Read.
Active (low) level indicates read cycle on the X-Bus.
Enable.
Active (high) level indicates valid data on the X-Bus.
XWR_XRW 15
O
O
3/6
V
SB
Write.
Active (low) level indicates a write cycle on the X-Bus.
Read/Write.
A high level indicates a read cycle on the X-Bus; a
low level indicates a write cycle on the X-Bus.
XD7-0
24-31
I/O
IN
TS
/O
3/6
V
SB
Data Bus.
8-bit data multiplexed with the address lines XA27-4.
XA11-4,
XA3-0
1-8
16-19
O
O
3/6
V
SB
Address Bus.
The XA27-12 address lines are always multiplexed
with the data lines.
XSTB2-0
32-34
O
O
3/6
V
SB
Address Strobes.
Control the strobe of up to three external
latches for the multiplexed address lines.
XCS3-0
20-23
O
O
3/6
V
SB
Chip Selects.
Control the selection of up to four devices residing
on the X-Bus.
XRDY
9
I
IN
TS
V
SB
I/O Ready.
Instructs the PC8741x to extend the access cycle.
XIRQ
10
I
IN
TS
V
SB
X-Bus Interrupt.
Converted into serial interrupt by the Interrupt
Serializer. The system configuration includes the interrupt number
associated with this signal.