microprocessor is the heart of any normal computer, whether
it is a desktop machine, a server or a laptop. The microprocessor
you are using might be a Pentium, a K6, a PowerPC, a Sparc
or any of the many other brands and types of microprocessors,
but they all do approximately the same thing in approximately
the same way. The computer you are using to read this page
uses a microprocessor to do its work. The microprocessor is
the heart of any normal computer, whether it is a desktop
machine, a server or a laptop. The microprocessor you are
using might be a Pentium, a K6, a PowerPC, a Sparc or any
of the many other brands and types of microprocessors, but
they all do approximately the same thing in approximately
the same way.
Performance and Trends
The number of transistors available has a huge effect on the
performance of a processor. As seen earlier, a typical instruction
in a processor like an 8088 took 15 clock cycles to execute.
Because of the design of the multiplier, it took approximately
80 cycles just to do one 16-bit multiplication on the 8088.
With more transistors, much more powerful multipliers capable
of single-cycle speeds become possible. More transistors also
allow for a technology called pipelining. In a pipelined architecture,
instruction execution overlaps. So even though it might take
five clock cycles to execute each instruction, there can be
five instructions in various stages of execution simultaneously.
That way it looks like one instruction completes every clock
modern processors have multiple instruction decoders, each
with its own pipeline. This allows for multiple instruction
streams, which means that more than one instruction can complete
during each clock cycle. This technique can be quite complex
to implement, so it takes lots of transistors.
The trend in processor design has primarily been toward full
32-bit ALUs with fast floating point processors built in and
pipelined execution with multiple instruction streams. The
newest thing in processor design is 64-bit ALUs, and people
are expected to have these processors in their home PCs in
the next decade. There has also been a tendency toward special
instructions (like the MMX instructions) that make certain
operations particularly efficient, and the addition of hardware
virtual memory support and L1 caching on the processor chip.
All of these trends push up the transistor count, leading
to the multi-million transistor powerhouses available today.
These processors can execute about one billion instructions