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Chapter 5

Signal Descriptions

105

20695H/0—March 1998

AMD-K6® Processor Data Sheet

Preliminary Information

5.33

M/IO# (Memory or I/O)

Output

Summary

The processor drives M/IO# during a bus cycle to indicate

whether it is addressing the memory or I/O space. If M/IO# = 1,

the processor is addressing memory or a memory-mapped I/O

port as the result of an instruction fetch or an instruction that

loads or stores data. If M/IO# = 0, the processor is addressing an

I/O port during the execution of an I/O instruction. In addition,

M/IO# is used to define other bus cycles, including interrupt

acknowledge and special cycles. (See Table 19 on page 119 for

more details.)

Driven and Floated

M/IO# is driven off the same clock edge as ADS# and remains in

the same state until the clock edge on which NA# or the last

expected BRDY# of the cycle is sampled asserted. M/IO# is

driven during memory cycles, I/O cycles, special bus cycles, and

interrupt acknowledge cycles.

M/IO# is floated off the clock edge that BOFF# is sampled

asserted and off the clock edge that the processor asserts HLDA

in response to HOLD.

AMD-K6 Datasheet(PDF) 123 Page - Advanced Micro Devices