| 486 |
The
16 additional pins on a 486 CPU compared to a 386 CPU provide 32-bit
data path, the extra
pin on a 486SX cpu disables the chips built in math coprocessor and the
extra pins on the Pentium processor allows for a 64-bit data path and
make dual pipeline possible
|
| Pentium PRO |
Contains
3 x 16 Pipeline Levels,compared to that of 3 x 4 of the 486 or Pentium
standard. The first part of CPU’s pipeline breaks
instructions
down into Micro Ops (NexGen Technology)
16-bit code contains lots of instructions called Practical Register
Referances which cause a pipeline stall that will slow down the CPU in
clock cycle losses.
In 32-bit instructions the
Pro would just about double the performance, it is therefore been
optimised for high end operating systems, like Windows NT
It contains 2 silicon chips:
(1) The Processor itself
(2) 256K close coupled level 2 cache running at the processor
speed
|
| SEC
& Intel Processors |
Single
Edge Contact, designed for the Pentium II enables the chip to be
mounted on its side rather than having numerous amounts of
fragile pins. Avoid mixing tin plated and gold plated
connections, when different metals come into contact with one another a
galvanic corrosion occures that causes the metals to corrode.
Intel processors run in 3 different modes:
Real Mode
Protected Mode
Virtual Mode
Real mode is what the CPU boots into
Protected Mode, processors ability to isolate programs in their own
protected memory therefore those programs cannot know that other
programs
exist. The 386 can isolate programs in their own memory
segment which
ranges from one byte to 4Gb. With virtual memory support
built in this
amount can be extended to 4TB (terabytes)
Virtual Mode, enables the 386 etc. to create virtual processors (8086)
complete with i/o trapping which can co-exist with protected mode
programs |
| Silicon
Graphics |
SG
CPU's are RISC based
Silicon Graphic machines also run in SMP (Symmetric Multi-Processor)
with up to 40 CPU's all running together just like the supercomputer
Intel built for the CIA it
is like having 20 computers all running together at the same time
performing the same task. |
| Clock
Speeds Explained |
The
processor's strength is in the speed at which it performs these routine
operations, hence the clock speed.. Timing throughout the
system
must be synchronized. For each clock tick, the system pulses
a
request through the microprocessor and this creates the corresponding
cycle of the system. A cycle can represent a single request
or
answer from the microprocessor.
Ticks of the clock are counted in millions. There are
millions of
clock ticks or cycles per second. This equates to megahertz
(MHz)
or millions of cycles per second.
The heart of the clock is a thin slice of quartz crystal.
When
electricity passes through it, the quartz vibrates. Each
vibration generates an electric pulse which travels by wire to every
component on the system. Components use pulses to coordinate
messages they send to each other. The steady clock beat guarantees that
when one component sends a signal, another is timed and ready to
receive it. |
| Diagrams |
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