Information Technology Reference
In-Depth Information
Users
A
P
P
A
P
P
A
P
P
User-
mode
System
Library
File
System
TCP
IP
networking
Kernel-user
Interface (Abstract
virtual machine)
OS
Virtual
Memory
Kernel-
mode
CPU
scheduling
Hardware-Speci
c Software
and Device Drivers
Hardware
Abstraction Layer
CPU
Address
Translation
Hardware
Graphics
Processor
Network
Figure1.3: A general-purpose operating system: expanded view
tions from hardware input and output devices, so that applications can
be written independently of which specific keyboard, mouse or disk drive
is being used on a particular computer.
We next discuss these three roles in a bit more detail.
1.1.1
Resource sharing: Operating system as referee
Sharing is central to most uses of computers. Right now, my laptop is running
a browser, podcast library, text editor, email program, document viewer, and
newspaper. The operating system must somehow keep all of these activities sep-
arate, yet allow each the full capacity of the machine if the others aren't running.
At a minimum, when one program stops running, the operating system should
