AMD AMD-K6-2/400 User Guide - Page 194

Preliminary Information AMD-K6™-2E+ Embedded Processor Data Sheet 23542A/0-September 2000 HOLD-Initiated Inquire Hit to Modified Line Figure 68 on page 173 shows the same sequence as Figure 67 on page 171, but in Figure 68 the inquire cycle hits a modified line and the processor asserts both HIT# and HITM#. In this example, the processor performs a writeback cycle immediately after the inquire cycle. It updates the modified cache line to external memory (normally, external cache or DRAM). The processor uses the address (A[31:5]) that was latched during the inquire cycle to perform the writeback cycle. The processor asserts HITM# throughout the writeback cycle and negates HITM# one clock edge after the last expected BRDY# of the writeback is sampled asserted. When the processor samples EADS# during the inquire cycle, it also samples INV to determine the cache line MESI state after the inquire cycle. If INV is sampled asserted during an inquire cycle, the processor transitions the line (if found) to the invalid state, regardless of its previous state. The cache line invalidation operation is not visible on the bus. If INV is sampled negated during an inquire cycle, the processor transitions the line (if found) to the shared state. In Figure 68 the processor samples INV asserted during the inquire cycle. In a HOLD-initiated inquire cycle, the system logic can negate HOLD off the same clock edge on which EADS# is sampled asserted. The processor drives HIT# and HITM# on the clock edge after the clock edge on which EADS# is sampled asserted. 172 Bus Cycles Chapter 7