History of computers generations - Limitations of computer

LIMITATIONS OF COMPUTERS :-

Despite its various benefits, a computer does have the following limitations:-

A computer has no intelligence of its own. It depends upon user's instructions for any kind of task. It can not replace a human brain. •
It works only on stored procedures and cannot think on its own. It does only those tasks which are already instructed to it.
It can not correct invalid input. If mistakenly given incorrect data or instructions, it doesnot have the ability to correct it.
It does not have feelings. It does not turns on itself or programming itself.
Prolonged or improper computer use can lead to injuries or disorders of the hands wrists, elbows, eyes, necks, and back. Computer users can protect themselves from these health risks through proper workplace design, good posture while at the computer, and appropriately spaced work breaks.
Adults, teen, and children around the world are using computers to share publicly their photos, videos, journals, music, and other personal information. Some of these unsuspecting, innocent computer users have fallen victim to crimes committed by dangerous strangers.
HISTORY / EVOLUTION OF COMPUTERS :-

The development of the modern day computer was the result of advances in technologies and man's need to compute. History reveals a clear pattern in the evolution of computers.

In the beginning, many devices have been used in the processing of data. Like: Abacus Napier Bones, Difference Engine, Analytical Engine etc.

The following section deals with the periodic advancements in the field of computers:

(a) Abacus :-

Abacus is a manual calculating device mainly used to perform addition and sub .
It is one of the earliest counting devices consists of a frame set with rods on or beads are moved.
Simple addition and subtraction were carried out rapidly and effectively by the beads appropriately.
It is still a very common device in China.

(b) Napier Bones :-

Napier's bones, also called Napier's rods, were invented by John Napier (1550-1617), a Scottish mathematician and scientist.
The 'bones' consist of a set of rectangular rods, each marked with a counting number at the top, and the multiples of that number down their lengths.
When aligned against the row of multiples, any multiple of the top number can be read off from right to left by adding the digits in each parallelogram in the appropriate row.

Pascaline also called Arithmetic Machine the first calculator or adding machine was designed and built by the French mathematician-philosopher Blaise Pascal in 1642.
This machine could only do addition and subtraction, with numbers being entered by manipulating its dials.
Fig. 1.6 (Pascaline)

Leibnitz's Calculator / Stepped Reckoner :-

In 1671, German mathematician, Gottfried Leibnitz invented a calculating machine called the Stepped Reckoner.
This calculating machine could add, subtracts, multiply, divide and evaluate square roots by series of stepped addition.
This machine consisted of cylinders instead of dials.

(e) Difference Engine :-

The Difference Engine, designed in 1820s by British mathematician Charles Babbage to perform calculations.

Fig. 1.8 (Difference Engine)

Difference engines were so called because of the mathematical principle on which they were based, namely, the method of finite differences.
This method was based upon arithmetic addition and removes the need for multiplication and division which were more difficult to implement mechanically
Difference Engine was able to compute tables of numbers, such as logarithm tables
This machine was stream driven and very large in size.
It was mainly designed to perform accurate calculations for a British project, but after continuous efforts, the project was closed without any success.

(f) Analytical Engine:-

The Analytical Engine was the world's first general-purpose computer designed in 1830s by the British mathematician Charles Babbage. After his
Difference Engine failed its test, Babbage started the design of the Analytical Engine. The Analytical Engine introduced a number of computing concepts still present in modern computers also .
This machine had two main parts: "Store" and the “Mill", analogous to today "memory" and "processor •
This machine used punched cards to perform input-output operations. •
The Analytical Engine was much more than a calculator, it was capable of performin comparisons and modifications to a stored data value.

(G) Hollerith's Tabulating Machine :-

This machine was the first automatic data processing system used to count the 1890 U.S. census.
This machine was developed by Herman Hollerith, an American mathematician. Fig. 1.10 (Hollerith's Tabulating Machine)
The system used a hand punch to record the data in punch cards and a machine to count them.
Hollerith's punch cards and tabulating machines were a step toward computing

(h) Mark - 1 Computer (1937-44):-

The Mark - I computer also called the Automatic SequencemControlled Calculator was first fully automatic calculating machine developed in 1937.
It was an electromagnetic computer, which was used to perform operations, like- addition, subtraction, multiplication, division etc.
It was huge in size and its design was very complex, but was very reliable,

(i) The Atanasoff-Berry Computer (1939-42) :-

The Atanasoff-Berry Computer (ABC) was the first electronic digital machine developed by Dr. John Atanasoff.
It used vacuum tubes and capacitors for internal logic and storage respectively.

(1) The ENIAC (1943-46) :-

The ENIAC (Electronic, Numerical, Integrator, Analyzer and Computer) was the first general purpose electronic computer developed by Prof. J. Presper Eckert and Prof. John Mauchly in 1943.
It used more number of vacuum tubes (approx. 19000) :-
.
It was big in size and very limited storage capacity.

(k) The EDVAC (1946-52) :-

The EDVAC (Electronic Discrete Variable Automatic Computer) was the successor of the ENIAC made by the same designers: Mauchly and Eckert.
Unlike its predecessor the ENIAC, EDVAC was binary rather than decimal i.e. it can data and instructions in the binary form (0 and 1) instead of decimal number used by a human being .