AMD AMD-K6-2/500AFX Data Sheet - Page 187

21850J/0-February 2000 Preliminary Information AMD-K6®-2 Processor Data Sheet Stop Grant and Stop Clock States Figure 74 and Figure 75 show the processor transition from normal execution to the Stop Grant state, then to the Stop Clock state, back to the Stop Grant state, and finally back to normal execution. The series of transitions begins when the processor samples STPCLK# asserted. On recognizing a STPCLK# interrupt at the next instruction retirement boundary, the processor performs the following actions, in the order shown: 1. Its instruction pipelines are flushed 2. All pending and in-progress bus cycles are completed 3. The STPCLK# assertion is acknowledged by executing a Stop Grant special bus cycle 4. Its internal clock is stopped after BRDY# of the Stop Grant special bus cycle is sampled asserted and after EWBE# is sampled asserted (if EWBE# is masked off, then entry into the Stop Grant state is not affected by EWBE#) 5. The Stop Clock state is entered if the system logic stops the bus clock CLK (optional) STPCLK# is sampled as a level-sensitive input on every clock edge but is not recognized until the next instruction boundary. The system logic drives the signal either synchronously or asynchronously. If it is asserted asynchronously, it must be asserted for a minimum pulse width of two clocks. STPCLK# must remain asserted until recognized, which is indicated by the completion of the Stop Grant special cycle. Chapter 5 Bus Cycles 167