Run; Halted (Halted); Cop/Scan Interface - IBM PowerPC 604 User Manual

7.2.10.4 Run (RUN)-lnput
The run (RUN) signal is input only on the 604. Following are the state meanings and timing
comments for the RUN signal.
State Meaning
Asserted- Forces the internal clocks to continue running during nap
mode, allowing bus snooping to occur.
Negated-Internal clocks are inhibited from running when 604 is in
nap mode.
For additional information regarding the nap mode, refer to Section 4.5.16, "Power
Management."
Timing Comments Assertion/Negation-Assertion may occur asynchronously
to the
604 input clock; and must be held asserted for a minimum of 3 bus
clock cycles before snoop activity.
7 .2.10.5 Halted (HALTED) -Output
The halted (HALTED) signal is output only on the 604. Following are the state meaning
and timing comments for the HALTED signal.
State Meaning Asserted-Indicates that the internal clocks have stopped due to the
604 entering nap mode, or a JTAG/COP request.
Negated-Indicates that internal clocks are running.
Timing Comments Assertion/Negation-Occurs synchronously with internal processor
clock.
For additional information regarding the nap mode, refer to Section 4.5.16, "Power
Management."
7 .2.11 COP/Scan Interface
The 604 has extensive on-chip test capability including the following:
• Built-in instruction and data cache self test (lnST)
• Debug controVobservation (COP)
• Boundary scan (IEEE 1149.1 compliant interface)
The BIST hardware is not exercised as part of the POR sequence. The COP and boundary
scan logic are not used under typical operating conditions.
Detailed discussion of the 604 test functions is beyond the scope of this document;
however, sufficient information has been provided to allow the system designer to disable
the test functions that would impede normal operation.
The COP/scan interface is shown in Figure 7-2. For more information, see Section 8.10.1,
"IEEE 1149.1 Interface Description."
Chapter 7. Signal Descriptions
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