
18
AMD-K5 Processor Data Sheet 18522F/0—Jan1997
PRELIMINARY INFORMATION
D63–D0 Data Lines Input/Output
The D63–D0 signals are the 64-bit data bus. These signals are
driven during the second and subsequent clocks of write
cycles, with valid bytes indicated by BE7–BE0. They are sam-
pled when the BRDY signal is asserted for read cycles. (See
Switching Characteristics t
34
and t
35
.)
DP7–DP0 Data Parity Input/Output
The DP7–DP0 signals provide even parity, one for each of the
eight bytes of the data bus. The eight data parity signals corre-
spond to the eight bytes of the data bus as follows:
These signals are driven with the data bus. Read cycles that do
not provide even parity when the read data is driven result in
the assertion of PCHK. Byte enables are negated for invalid
data bytes. For systems that do not use parity, DP7–DP0 should
be connected to V
CC
through a pull-up resistor. (See PCHK and
Switching Characteristics t
34
and t
35
.)
EADS Valid External Address Input
The EADS signal indicates that a valid address is driven on the
address bus during inquire cycles. EADS has an internal pull-
up resistor. (See Switching Characteristics t
16a
and t
17
.)
EWBE External Write Buffer Empty Input
External system logic notifies the processor of pending buff-
ered write cycles by negating the EWBE signal. The processor
will hold writes to exclusive or modified cache lines until
EWBE is asserted.
FERR Floating-Point Error Output
The FERR signal is asserted as a result of an unmasked float-
ing-point error. It is only floated during test.
■ DP7: D63–D56 ■ DP3: D31–D24
■ DP6: D55–D48 ■ DP2: D23–D16
■ DP5: D47–D40 ■ DP1: D15–D8
■ DP4: D39–D32 ■ DP0: D7–D0
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