Download Two Types of Software: System Software: Operating Systems

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Transcript
Two Types of Software:
1. Application Software: Instructions to accomplish a specific task (ie. MS Word, Internet Explorer)
2. System Software: Set of programs that help run the computer.
Operating Systems: Controls how computer system functions.
Utility Programs: Small programs that perform many general housekeeping tasks.
System Software:
Operating Systems
The operating system (OS) is the first thing loaded onto a computer. Without an operating system, a
computer is useless. Most desktop or laptop PC’s that you buy come pre-loaded with Windows 8
(newest). Macintosh computers come pre-loaded with OS X Mavericks. Many corporate servers use the
Linux or UNIX operating systems. The operating system on these computers is Windows7.
The Operating System's tasks, in the most general sense, fall into five categories:
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Processor Management
Memory and Storage Management
Device Management
Application Interface
User Interface
Processor Management
The operating system schedules the processes (tasks that come from the applications) that will be
executed by the CPU.
With a multi-tasking system, the operating system must arrange the execution of processes so that you
believe that there are several things happening at once. In order to give the appearance of lots of things
happening at the same time, the operating system has to switch between different processes thousands of
times a second.
Trouble can come if the user tries to have too many processes functioning at the same time so computer
freezes. This is called thrashing, and it usually requires user intervention to stop processes and bring
order back to the system (CTRL+ALT+DEL and End Task).
A dual core processor is a CPU with two separate cores in one physical processor, each with its own
cache. It's the equivalent of getting two microprocessors in one. Eventually, we will have multi-processor
systems.
Memory & Storage Management
The operating system must balance the needs of the various processes with the availability of the different
types of memory. For example, moving information in RAM to hard disk can greatly expand RAM space
at no cost. This technique is called virtual memory management.
Ranked in order of speed (fastest-slowest) and storage (smallest to largest), the types of memory in a
computer system are:

High-speed cache - This is fast, relatively small amounts of memory that are available to the CPU
through the fastest connections. Cache controllers predict which pieces of data the CPU will need next
and pull it from main memory into high-speed cache to speed up system performance.

Primary memory (or Main memory) - This is the RAM that you see measured in gigabytes when
you buy a computer.

Secondary memory - This is most often some sort of rotating magnetic storage (hard drive) that
keeps applications and data available to be used, and serves as virtual RAM under the control of the
operating system.
Device Management
The operating system manages the hardware and peripheral devices.
One of the challenges facing developers is keeping their operating systems flexible enough to run
hardware from the thousands of vendors manufacturing computer equipment. Today's systems can
accommodate thousands of different printers, disk drives and special peripherals in any possible
combination.
A driver (special program for the hardware) is a translator between hardware and the operating system or
application programs.
One reason that drivers are separate from the operating system is so that new functions can be added to
the driver without requiring the operating system itself to be modified, recompiled and redistributed.
Plug and Play refers to hardware that you can just plug in and it runs (may need to install driver).
Application Interface
Application Program Interface (API) is a way for software to interact with other software and system
resources. It uses blocks of code for similar procedures to prevent redundancy and make it easier for
software developers. Our Application Interface is Windows7.
User Interface
User interface (UI) brings structure to the interaction between a user and the computer.
Graphical user interface (GUI), sits as a layer above the operating system itself. Our User Interface is
Windows7 (login screen).
Reference: http://computer.howstuffworks.com/operating-system5.htm
Utility Programs
Appearance and Themes
Network and Internet Connections
Add or Remove Programs
System Maintenance
Printers and Other Hardware
System Restore
System Backup
Task Scheduler
Accessibility Options
Security Options