Electronic Digital Computer

Electronic digital computer is an information-processing device that accepts and processes data represented by discrete symbols. It is constructed primarily of electric or electronic devices.

An electronic digital computer possesses three advantages which make it extremely useful. They are:

1) High speed of operation

z) Precision and accuracy

(3) Reliability

Modern digital computers are constructed of electronic devices which enable the computer to complete an arithmetic calculation in approximately one-millionth of a second or less!

The size of computers has decreased by a factor of 10 since 1955. We expect another decrease, by a factor of 100. Small computers are commonly called minicomputers. They provide the power and speed of many large computers of only a few years ago. Through the utilization of high-speed electronic devices, notably transistors and solid-state devices¹, the speed and size of electronic digital computers has improved tremendously during the past decade. If the trend con­tinues, we shall have a computer the size of a shoebox capable of a bil­lion additions per second by the end of this decade.

The second advantage of an electronic digital computer is the great precision available in the calculation process. The precision of a com­puter may be defined in this way:

Precision. The degree of exactness² with which a quantity is stated. The amount of detail used in representing the data.

Precision is to be compared with accuracy. For example, four-place numerals³ are less precise than six-place numerals, nevertheless, a pro­perly computed four-place numeral might be more accurate than an improperly, computed six-place numeral. The accuracy of a computer is defined as follows:

Accuracy. The degree of freedom from error. Typically, a computer is able to perform calculations with numbers to a precision and accuracy of ten decimal places⁴.

The third advantage of the electronic digital computer is reliability, which is defined:

Reliability The quality of freedom from failure, usually expressed as the probability that a failure will not occur in a given amount of use.

The reliability of a typical computer might be expressed as a 95 per cent probability that it will not miscalculate one error in one week, and that it will not stop functioning within a month. A compu­ter is immensely more reliable than a man in completing long, diffi­cult calculations.

Now let us consider some of the disadvantages of electronic digital computers. Three of these disadvantages are:

(!) Limited inherent intelligence⁵

2. Limited language-handling capacity

3. High cost.

We say that the computer has limited inherent intelligence because it must be told what to do.

Also, the computer possesses a very limited language-handling capa­city at present. Typically, its vocabulary is limited to a hundred words, and its grammar is primitive. However, computers are being developed which will have expanded language capabilities.

A relationship between the computing power (essentially speed) and the cost of the computer has been deduced by Grosch:

Cost of computer = constant xV computing power

This relationship is often called Grosch's Law. Computing power increases as the cost squared.

Computing power — constant x (cost)²

For example, if we double the cost, we can obtain four times the com­puting power.