Digital computers based on manipulating discrete binary digits (1s and 0s). They are
generally more effective than analog computers for four principal reasons: they are
faster; they are not so susceptible to signal interference; they can transfer huge data
bases more accurately; and their coded binary data are easier to store and retrieve
than the analog signals.
For all their apparent complexity, digital computers are considered to be simple
machines. Digital computers are able to recognize only two states in each of its
millions of switches, "on" or "off", or high voltage or low voltage. By assigning
binary numbers to their states, 1 for "on" and 0 for "off", and linking many switches
together, a computer can represent any type of data from numbers to letters and
musical notes. It is this process of recognizing signals that is known as digitization.
The real power of a computer depends on the speed with which it checks switches
per second. The more switches a computer checks in each cycle, the more data it can
recognize at one time and the faster it can operate, each switch being called a binary
digit or bit.
A digital computer is a complex system of four functionally different elements: 1)
the central processing unit (CPU), 2) input devices, 3) memory-storage devices
called disk drives, 4) output devices. These physical parts and all their physical
components are called hardware.
Most digital computers store data both internally, in what is called main memory,
and externally, on auxiliary storage units. As a computer processes data and
instructions, it temporarily stores information internally on special memory
microchips. Auxiliary storage units supplement the main memory when programs
are too large and they also offer a more reliable method for storing data. Programs,
also called software, are detailed sequences of instructions that direct the computer
hardware to perform useful operations. Due to a computer's operating system
hardware and software systems can work simultaneously. An operating system
consists of a number of programs coordinating operations, translating the data from
different input and output devices, regulating data storage in memory, transferring
tasks to different processors, and providing functions that help programmers to write
software. In large corporations software is often written by groups of experienced
programmers, each person focusing on a specific aspect of the total project. For this
reason, scientific and industrial software sometimes costs much more than do the
computers on which the programs run.
1. The computers can be analog and digital.
2. Digital computers are generally less effective than analog computers.
3. Digital computers are considered to be complicated machines.
4. The real power of a computer depends on the speed with which it checks
switches per minute.
5. An operating system consists of a number of programmes coordinating
operations, translating the data from different input and output devices,
regulating data storage in memory, transferring tasks to different processors,
and providing functions that help -programmers to write software.