TECHNOLOGY GUIDE 2. COMPUTER SOFTWARE
SIGNIFICANCE OF SOFTWARE
Software- contains effective instructions given to the computer.
Less costly in 1950s, now make up a huge part of cost of modern computer systems
Software prices have increased
• Software: consist of computer programs
• Computer programs: sequences of instructions for the computer.
• Modern software uses stored program concept: stored programs are stored in the computer’s hardware. Programs
are accessed and the instructions are executed (followed) in the computer’s CPU.
• Computer programs include documentation: written description of the functions of the program.
Critical step to problems faced- better design and planning
Two major types of software:
Systems software: set of instructions that serve primarily as an intermediary between computer hardware and
application programs. System programming -creation and maintenance of systems software. Eg. Turn on
Application software: set of computer instructions that provide more specific functionality to a user-general word
processing, payroll program.
Class of programs that controls and supports the computer system and its information-processing activities. Facilitates
programming, testing, and debugging of computer programs.
System control programs: control the use of hardware, software and data resources of a computer system. Main
system control program is the Operating system.
Operating system (OS) supervises the overall operation of the computer, monitors computer status and
scheduling operations, allocates CPU time and main memory to programs running on the computer. Acts as
interface b/w user and hardware.
Functions of the operating system: OS manages program or programs
• Multi-tasking: management of two or more tasks or programs running on the computer system at the same
• Multi-threading: form of multi-tasking that involves running multiple tasks or threads within a single
• Multi-processing: computer system uses two or more processors to run more than one program at a given time
by assigning them to different processors.
• Virtual memory: process by which it simulates more main memory than actually exists in the computer
system. It divides an application program or module into fixed-length portions called pages.
• Interface design: ease or difficulty of interaction between user and computer
• Graphical User Interface (GUI) user has direct control of visible objects (like icons) and actions that replace
complex commands. • Natural user interfaces(NUIs) combine social interfaces, haptic interfaces, touch-enabled gesture-control
interfaces and spatial operating environments
• Social interface: user interface that guides the user through computer applications by using cartoon-like
characters, graphics, animation and voice commands.
• Haptic interface: allows user to feel a sense of touch by applying forces, vibrations and or motions to user. Eg
wii, apple iphone
• Spatial operating environment: user interface where the user stands or sits in front of one or more computer
screens and gestures with gloved hands to move images around, touch virtual objects, trace shapes and
navigate complex data.
TYPES OF OPERATING SYSTEMS
Operating environment are sets of computer programs that add features that enable system developers to create
applications without directly accessing the OS, they function only with an OS. Eg. Windows, Mac OS X, Linux
Operating systems for mobile devices: designed to support a single person using a mobile, hand-held device or
Small computer operating systems: support a single user or small workgroup users.
Large computer operating systems/midrange computer and mainframes): support a few or thousands of concurrent
users.-reliable, backup, security, fault tolerance and rapid processing speeds.
Plug and play: feature that can automate the installation of new hardware by enabling the OS to recognize new
hardwires and then automatically install the necessary software called device drivers.
SYSTEM SUPPORT PROGRAMS
Supports the operations, management, and users of a computer syste