Information System Literact Concepts by Hossein Bidgoli

Information System Literact Concepts by Hossein Bidgoli

we Define computers as a machine that accepts data as input , processes the data without human

interference using a set of stored instructions, and outputs information.

Computer programs consist of instructions written in a language understood by computers.

Data is raw facts and information is processes fact.

Types of processing

In Batch Processing, data is sent to the computer periodically, for example, every 24 hours,

every two weeks, or every month. Payroll is a good example where the data is not needed immidietly.

Transaction Processing required when data need immidiete response.

Disk Drives

Disk drives are used to read and store data or information from and to the disk in the main 

memory.

Main Memory/RAM

It is reffered to as RAM(Random Access Memory). This is a volatile memory. It will be lost

in event of power failure.

Since the main memorty of a microcomputer is limited , expensive and volatile, secondary storage

is used for mass storage.

Secondary storage devices are broadly classified as magnetic and optical.

Magnetic Storage Devices

Optical disks use laser beams , highly concentrated beams of light, to access and store data.

This technology can store vast amount of data. However, because optical technology is relatively

new, it is expensive.

An operating system is a set of programs that control and supervises computer hardware and 

software.

An operating system provides an interface between a computer and a user. It typically resides in

the main memory. A typical OS consists of two sets of programs: control programs and supervisor

programs.

Control Program manage the computer hardware and resources, including job management, resource

allocation, data management and data communication.