Hardware Reference
In-Depth Information
2.
Grasp bulb.
3.
Raise hand.
4.
Insert bulb into socket.
5.
Rotate clockwise one turn.
6.
Is bulb tight? If not, repeat step 5.
7.
End.
Overall, many more RISC instructions are required to do the job because each instruction is simpler
(reduced) and does less. The advantage is that there are fewer overall commands the robot (or
processor) has to deal with, and it can execute the individual commands more quickly, and thus in
many cases execute the complete task (or program) more quickly as well. The debate goes on whether
RISC or CISC is really better, but in reality there is no such thing as a pure RISC or CISC chip—it is
all just a matter of definition, and the lines are somewhat arbitrary.
Intel and compatible processors have generally been regarded as CISC chips, although the fifth- and
later-generation versions have many RISC attributes and internally break down CISC instructions into
RISC versions.
Note
The ARM processor used by Windows RT tablets is a RISC processor. Windows RT uses the
same tile-based interface as Windows 8, but x86 software is not compatible with Windows
RT.
MMX Technology
MMX technology was originally named for
multimedia extensions
, or
matrix math extensions
,
depending on whom you ask. Intel officially states that it is actually not an abbreviation and stands for
nothing other than the letters MMX (not being an abbreviation was apparently required so that the
letters could be trademarked); however, the internal origins are probably one of the preceding. MMX
technology was introduced in the later fifth-generation Pentium processors as a kind of add-on that
improves video compression/decompression, image manipulation, encryption, and I/O processing—
all of which are used in a variety of today's software.
MMX consists of two main processor architectural improvements. The first is basic: All MMX chips
have a larger internal L1 cache than their non-MMX counterparts. This improves the performance of
any and all software running on the chip, regardless of whether it actually uses the MMX-specific
instructions.
The other part of MMX is that it extends the processor instruction set with 57 new commands or
instructions, as well as a new instruction capability called single instruction, multiple data (SIMD).
Modern multimedia and communication applications often use repetitive loops that, while occupying
10% or less of the overall application code, can account for up to 90% of the execution time. SIMD
enables one instruction to perform the same function on multiple pieces of data, similar to a teacher
telling an entire class to “sit down,” rather than addressing each student one at a time. SIMD enables
the chip to reduce processor-intensive loops common with video, audio, graphics, and animation.
Intel also added 57 new instructions specifically designed to manipulate and process video, audio,
