The automatic electronic digital computer is a machine that utilizes electronic circuits to manipulate data expressed in a symbolic form according to specific rules in a predetermined but self-directed way. In brief, it is a machine which uses electronic circuits to handle symbolic  data. However, even this simplified definition is somewhat hard to absorb as a whole so let’s look at its individual parts to understand it better.

First of all, the computer is a machine. This means that it is inanimate . As it is non-living, it requires an outside power source and  without this source it stops working. This also means it can perform only those activities for which the basic capabilities have been specifically designed into the machine.

In other words, it is limited to its designed capabilities and the directions given to it. If separated from its outside power source, it ceases to function.

Second, it is automatic. This means that once started, it continues to run without outside interference.

Third, it is electronic; that is, it is made up of electronic circuits and runs on electrical energy.

Fourth, the computer is a symbol manipulator. It manipulates data, not physical entities. These data are represented as electronic impulses  within the machine. These electronic signals are combined to form number (digital) representations of data. Electronic devices are two-state devices.

For example, a switch is either on or off, a spot on the surface of a magnetic tape is either magnetized or not magnetized. Therefore, it seems natural and reasonable to use the base 2 or binary number system  as the basic data-representation method in the computer.

Only two digits exist in the binary number system, 0 (zero) and 1 (one). They can easily be matched to the two states of the electronic devices. Combinations of 0’s and l’s can be used to represent non-numeric data as well as numeric data.

Fifth, the computer must follow specific rules in manipulating data.  These rules are, in the main, the rules of Boolean algebra. That is, the computer can perform only the processes of addition, subtraction, multiplication, division, and comparison in addition to data transfer between components.


Sixth, the computer must follow a predetermined sequence of processes. That is, someone (the programmer) must  prepare a programme for the computer to follow.

Finally, the computer can follow the predetermined sequence in a self-directed way. It can store the programme within its own memory and then follow it through under its own direction, without outside guidance. That is, the computer can be made, in effect, to learn a  process, store the instructions in its memory, and follow them through, unaided by further supervision and direction.

This stored-programme characteristic is what differentiates the computer from other data processing machines. The instructions are stored in the memory and the  memory is accessible to a user. Since the memory is within reach of the user, the instructions can be changed easily. The computer can thus be given the ability to handle many different jobs. It is much more flexible than the “programmable” accounting machines because its programmes are a sequence of logic and arithmetic operations.


1. Line 1, to ‘utilize’ is to .
2. Line 6, to ‘absorb’ is to .
3. Line 9, ‘inanimate’ means .
4. Line 14, to ‘cease’ is to .
5. Line 19, ‘impulses’ are .
6. Line 45, ‘accessible’ means .
B. Mark the statements as True (T) or False (F).

1. Once the computer is started, it doesn’t need an outside power source.

2. In electronic devices, data are represented by various combinations of two digits.

3. A programme is a predetermined sequence of processes.

4. The computer doesn’t need further guidance while following through the programme in its memory.

5. The main purpose of this passage is to distinguish computers from programmable accounting machines.


1. What makes computers different from other data processing machines?
2. How can the user make the computer perform different tasks?

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