
Chapter 2
Internal Architecture
13
23542A/0—September 2000
AMD-K6-2E+ Embedded Processor Data Sheet
Preliminary Information
Figure 1. AMD-K6-2E+ Processor Block Diagram
Decoders
Decoding of the x86 instructions begins when the on-chip L1
instruction cache is filled. Predecode logic determines the
length of an x86 instruction on a byte-by-byte basis. This
predecode information is stored, along with the x86
instructions, in the L1 instruction cache, to be used later by the
decoders. The decoders translate on-the-fly, with no additional
latency, up to two x86 instructions per clock into RISC86
operations.
Note:
In this chapter, “clock” refers to a processor clock.
The AMD-K6-2E+ processor categorizes x86 instructions into
three types of decodes—short, long, and vector. The decoders
process either two short, one long, or one vector decode at a
time.
The three types of decodes have the following characteristics:
I
Short decodes—x86 instructions less than or equal to seven
bytes in length
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