Chapter 3x

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Dec 2, 2013 (4 years and 7 months ago)


Guide to Operating Systems 4


Palmer & Walters

Chapter 3

Operating System Hardware Components


This chapter teaches students about various CPU designs and details some popular CPU types
across different brands. It will
also explain typical hardware specifications with processors that
affect OS choice and performance.


Explain operating system hardware components, which will include design type, speed,
cache, address bus, data bus, control bus, and CPU schedul

Describe the basic features and system architecture of popular PC processors

Understand how hardware components interact with operating systems

Key Terms

address bus
An internal communications pathway inside a computer that specifies the source and
address for memory reads and writes. The address bus is measured by the number of bits of information it
can carry. The wider the address bus (the more bits it moves at a time), the more memory available to the
computer that uses it.

backward compat

A significant number of features from an older chip can function on a newer


A path or channel between a computer’s CPU and the devices it manages, such as memory and disk

cache controller

Internal computer hardware that manages t
he data going into and loaded from the
computer’s cache memory.

cache memory

Special computer memory that temporarily stores data used by the CPU. Cache memory
is physically close to the CPU, and is faster than standard system memory, enabling faster retri
eval and
processing time.

Complex Instruction Set Computing (CISC)

A computer CPU architecture in which processor
components are reconfigured to conduct different operations as required. Such computer designs require
any instructions and more complex instr
uctions than other designs. Compare to Reduced Instruction Set
Computing (RISC).

control bus

An internal communications pathway that keeps the CPU informed of the status of particular
computer resources and devices, such as memory and disk drives.



part of a processor used to read and execute instructions.

data bus

An internal communications pathway that allows computer components, such as the CPU,
display adapter, and main memory, to share information. Early personal computers used an 8
bit data bu
More modern computers use 32

or 64
bit data buses.

based cache

level cache in a XEON CPU that stores decoded
instructions and delivers them to the processor at high speed.

Explicitly Parallel Instruction Computing (EPIC)

A computer CPU
architecture that
grew out of the RISC
based architecture, and enables the processor to work faster by
performing several operations at once, predicting and speculating about operations that
Guide to Operating Systems 4


Palmer & Walters

will come next (so that they are even completed before requested)
. EPIC uses larger and
more work area registers than CISC or traditional RISC
based CPU architectures. See
Complex Instruction Set Computing (CISC) and Reduced Instruction Set Computing

external clock speed

The speed at which the processor communic
ates with the memory
and other devices in the computer; usually one
fourth to one
half the internal clock

threading (HT)

An Intel multithreading technology that enables a single
processor to appear to the operating system as two separate proce
ssors, in which
multiple threads of software applications are run simultaneously on one processor.

instruction set

In a computer CPU, the group of commands (instructions) the processor
recognizes. These instructions are used to conduct the operations requi
red of the CPU
by the operating system and application software.

internal clock speed

The speed at which the CPU executes internal commands,
measured in megahertz (millions of clock ticks per second) or gigahertz (billions of
clock ticks per second). Inte
rnal clock speeds can be as low as 1 MHz and as high as
more than 3 GHz.

interrupt request (IRQ)

A request to the processor so that a currently operating
process, such as a read from a disk drive, can be interrupted by another process, such as
a write into


level 1 (L1) cache

Cache memory that is part of the CPU hardware. See cache memory.

level 2 (L2) cache

Cache memory that, in most computer CPU designs, is located on
hardware separate from, but close to, the CPU.

level 3 (L3) cache

Cache memory th
at is located on a chip, which is separate from, but
close to the CPU, when L1 and L2 cache are both already built into the CPU.

math coprocessor

A module optimized to perform complex math calculations. Early
system architectures have a processor and an op
tional slot for a math coprocessor.
Modern system architectures have a CPU with one or more built
in math=coprocessors.

Multimedia Extension (MMX)

A CPU design that permits the processor to manage
certain multimedia operations

graphics, for example

and more directly. MMX
technology improves computer performance when running software that requires
multimedia operations.

multiprocessor computer

A computer that uses more than one CPU.


Running several program processes or parts (threads) a
t the same time.


A CPU design that permits the processor to operate on one instruction at the
same time it is fetching one or more subsequent instructions from the operating system
or application.

Reduced Instruction Set Computing (RISC)

A computer CPU design that dedicates
processor hardware components to certain functions. This design reduces the number
and complexity of required instructions and, in many cases, results in faster
performance than CISC CPUs. Compare to Complex Instructio
n Set Computing

processor computer

A computer capable of supporting only a single CPU.

Streaming SIMD Extensions

instruction, multiple
data stream processing for
enhanced multimedia.

system architecture

The computer hardware design th
at includes the processor (CPU),
and communication routes between the CPU and the hardware it manages, such as
memory and disk storage.

Guide to Operating Systems 4


Palmer & Walters


Used to hold data or programming code in a computer. The size of a word varies
among computers. 16
bit computers ha
ve a word of 16 bits and a 64
bit computer has a
word of 64 bits.