
Chapter 14
Clock Control
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23542A/0—September 2000
AMD-K6-2E+ Embedded Processor Data Sheet
Preliminary Information
14
Clock Control
14.1
Clock Control States
The standard-power versions of the AMD-K6-2E+ processor
support five modes of clock control. The low-power versions of
the AMD-K6-2E+ processor support six modes of clock control.
The processor can transition between these modes to maximize
performance, to minimize power dissipation, or to provide a
balance between performance and power. (See “Power
Dissipation” on page 289 for the maximum power dissipation of
the AMD-K6-2E+ processor within the normal and
reduced-power states.) The clock-control states supported are:
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Normal State
—The processor is running in Real Mode,
Virtual-8086 Mode, Protected Mode, or System Management
Mode (SMM). In this state, all clocks are running—including
the external bus clock CLK and the internal processor
clock—and the full features and functions of the processor
are available.
Halt State
—This low-power state is entered following the
successful execution of the HLT instruction. During this
state, the internal processor clock is stopped.
Stop Grant State
—This low-power state is entered following
the recognition of the assertion of the STPCLK# signal.
During this state, the internal processor clock is stopped.
Stop Grant Inquire State
—This state is entered from the
Halt state and the Stop Grant state as the result of a
system-initiated inquire cycle.
Enhanced Power Management (EPM) Stop Grant State
: This
low-power state is available on low--power versions of the
processor. It is entered following the write of a non-zero
value to the SGTC field of the EPM 16-byte I/O block for the
purpose of performing dynamic processor core frequency
and voltage ID state transitions using AMD PowerNow!
technology. During this state, the internal processor clock is
stopped.
Stop Clock State
—This low-power state is entered from the
Stop Grant state when the CLK signal is stopped.
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