
Extended Temperature 82439TX (MTXC) Datasheet
9
PRELIMINARY
2.0.
SIGNAL DESCRIPTION
This section provides a detailed description of each signal. The signals are arranged in functional groups
according to their associated interface.
The “#” symbol at the end of a signal name indicates that the active, or asserted state occurs when the signal
is at a low voltage level. When “#” is not present after the signal name, the signal is asserted when at the high
voltage level.
The terms assertion and negation are used exclusively. This is done to avoid confusion when working with a
mixture of “active low” and “active high” signal. The term assert, or assertion indicates that a signal is active,
independent of whether that level is represented by a high or low voltage. The term negate, or negation
indicates that a signal is inactive.
The I/O buffer types are shown below:
Buffer Type
I
O
I/O
s/t/s
od
3.3V/2.5V
Description
input only signal
totem pole output
bi-direction, tri-state input/output pin
sustained tri-state
open drain
Indicates the buffer is 3.3V or 2.5V only, depending on the voltage (3.3V or 2.5V) connected
to VccX pins.
Indicates that the output is 3.3V and input is 3.3V receiver with 5V tolerance.
Indicates 3.3V receiver with 5V tolerance.
3.3V/5V
5V
2.1.
MTXC Signals
2.1.1.
HOST INTERFACE
Name
Type
Description
A[31:3]
I/O
3.3V/2.5V
Address Bus.
A[31:3] connects to the address bus of the CPU. During CPU
cycles A[31:3] are inputs. The MTXC drives A[31:3] during inquire cycles on
behalf of PCI initiators. Bits A[31:26] act as inputs when RST# is active
BE[7:0]#
I
3.3V/2.5V
Byte Enables.
The CPU byte enables indicate which byte lane the current
CPU cycle is accessing. All eight byte lanes must be provided to the CPU if
the cycle is a cacheable read regardless of the state of BE[7:0]#.
ADS#
I
3.3V/2.5V
Address Status.
CPU asserts ADS# in T1 of the CPU bus cycle.
BRDY#
O
3.3V/2.5V
Bus Ready.
The MTXC asserts BRDY# to indicate to the CPU that data is
available on reads or has been received on writes.
NA#
O
3.3V/2.5V
Next Address.
This signal is asserted by the MTXC to indicate to the
Processor that it is ready to process a second cycle.