5-74
Bus Interface
AMD-K5 Processor Technical Reference Manual
18524C/0—Nov1996
5.2.27
HLDA (Bus-Hold Acknowledge)
Output
Summary
When system logic asserts HOLD, the processor completes any
in-progress bus cycle, floats its cycle-driving outputs, and
asserts HLDA as an acknowledgment. While HLDA is asserted,
another bus master can drive cycles on the bus, including
inquire cycles to the processor.
Driven
The processor drives HLDA every clock. The processor floats
the cycle-driving outputs on the bus and asserts HLDA two
clocks after the last BRDY of an in-progress bus cycle, if such a
cycle is in progress when HOLD is asserted, or two clocks after
the assertion of HOLD, whichever comes last. The processor
continues to float the bus and assert HLDA until two clocks
after HOLD is negated.
HLDA is driven during cache hits in the normal operating
modes (Real, Protected, and Virtual-8086) and in SMM, but
writebacks wait until HLDA is negated. HLDA is also driven in
the Shutdown, Halt, Stop Grant, and Stop Clock states; or
while AHOLD, BOFF, RESET, INIT, or PRDY is asserted.
HLDA is not driven during processor-originated bus cycles,
because any such pending bus cycle completes before the pro-
cessor asserts HLDA.
Details
HLDA is the processor’s acknowledgment to HOLD. HLDA
indicates that any in-progress bus cycle has completed and that
the output and bidirectional signals used for memory or I/O
accesses are floating. Table 5-12 shows the signals floated. The
same set of signals is floated with BOFF.
Table 5-12. Outputs Floated When HLDA is Asserted
Address and
Address Parity
Cycle Definition
and Control
Data and
Data Parity
Cache
Control
A31–A3
D/C
D63–D0
CACHE
ADS
LOCK
DP7–DP0
PCD
ADSC
M/IO
BE7–BE0
PWT
AP
SCYC
N/A
N/A
N/A
W/R
N/A
N/A
Summary of Contents for AMD-K5
Page 1: ...AMD K5 Processor Technical Reference Manual TM...
Page 10: ...x AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 24: ...1 4 Overview AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 54: ...2 30 Internal Architecture AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 116: ...4 26 Performance AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 356: ...6 44 System Design AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 380: ...7 24 Test and Debug AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 396: ...A 16 AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 406: ...I 10 Index AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...