Difference Between Internal and External Memory

Q16. Distinguish between internal and external memory.

Ans. The term “memory” has two different meanings in the context of computer components. One meaning, which most commonly involves RAM (random access memory), is a computer component used to temporarily hold data for processing by the computer. The other meaning is as a form of rewritable permanent storage, specifically one using a system called “flash memory.” In a computer, internal memory normally means RAM, while external memory means flash memory storage devices such as a USB stick. The biggest difference is that RAM is cleared whenever the computer is shut down, while data on flash memory storage remains until you delete or replace it.

Digital, Analog and Hybrid Computers

Q35. How are digital, analog and hybrid computers different from one another?

Ans. Digital Computer

The digital computers work upon discontinuous data. They convert the data into digits (binary digits 0 and 1) and all operations are carried out on these digits at extremely fast rates. A digital computer basically knows how to count the digits and add the digits. Digital Computers are much faster than analog computers and far more accurate. Computers used for business and scientific applications are digital computers.

 

Analog Computer

In analog computers, continuous quantities are used. Computations are carried out with physical quantities such as voltage, length, current, temperature etc. the devices that measure such quantities are analog devices, for example voltmeter, ammeter. Analog computers operate by measuring rather than counting. The main advantage of analog computers is that all calculations take place in parallel and hence these are faster. But their accuracy is poor as compared to digital counterparts. Analog computers are mostly used in engineering and scientific applications. An electronic weighing scale is an example of an analog computer.

 

Hybrid Computer

Hybrid computers utilize the best qualities of both the digital and analog computers. In these computers some calculations take place in analog manner and rest of them take place in digital manner. Hybrid computers are best used in hospital where analog part is responsible for measurement of patient’s heart beat, blood pressure, temperature and other vital signs and then the operation is carried out in digital fashion to monitor patient’s vital sign. Hybrid computers are also used in weather forecasting.

 

Super Computers and Name of a Supercomputer installed in India

Q34. What do you understand by the term ‘Super Computers’? Give the name of a supercomputer installed in India.

Ans. Super computers are the most powerful computers among digital computers. These consist of several processors running together thereby making them immensely faster and powerful. These computers are capable of handling huge amounts of calculations that are beyond human capabilities. Super computers can perform billions of instructions per second. Some of the today’s super computers have the computing capability equal to that of 40,000 micro computers. A Japanese super-computer has calculated the value of Pi (π) to 16 million decimal places. These are mainly used in application like weather forecasting, nuclear science research, aerodynamic modeling, seismology, metrology etc.

 

Following are a few names of supercomputers installed in India:

  1. CRAY XMP-14 brought from US.
  2. Flosolver Mk3 is in use at the Centre for Atmospheric Sciences of the Indian Institute of Science (IISc), Banglore.
  3. PACE (Processor for Aerodynamic Computation and Evaluation), develop by the Hyderabad-based Advanced Numerical Research and Analysis Group (ANURAG).
  4. PARAM developed by the Pune-based Centre for Development of Advanced Computing (C-DAC).

Three Advantages of Computer Data Processing over Manual Methods

Q33. List at least three advantages of computer data processing over manual methods.

Ans. Following are the three advantages of computer data processing over manual methods:

  1. Speed

Computers are much faster as compared to human beings. A computer can perform task in minute that may take days if performed manually. A modern computer can execute millions of instructions in one second.

  1. High Storage Capacity

Computers can store a large amount of information in very small space. A CDROM of 4.7 inch diameter can store all the 33 volumes of Encyclopedia Britannica and will still have room to store more information. Bubble memories can store 6,250,000 bits per square centimeter of space.

  1. Accuracy

Computers can perform all the calculations and comparisons accurately provided the hardware does not malfunction.

Compare Microcomputers with Minicomputers and Mainframe in terms of Size, Cost and Capabilities

Q32. Compare microcomputers with minicomputers and mainframe in terms of size, cost and capabilities.

Ans. Microcomputers

A microcomputer is a computer whose CPU is a microprocessor. A microprocessor is a processor whose all components are on a single integrated-circuit chip. Those are normally single-microprocessor, single-user systems designed for performing basic operations like educational, training, small business applications, playing games etc.

 

Minicomputers

Minicomputers, also called mid-range servers, are more powerful computers than micro-computers in terms of processing power and capabilities. Minicomputers are mainly multiuser systems where many users simultaneously work on the systems. Mini computers possess greater storage capacity and larger memories as compared to microcomputers. These are even capable of handling more input-output devices.

 

Mainframe Computers

Mainframe computers are designed to handle huge volumes of data and information. These can support more than hundred users at same time. These very large and expensive computers have great processing speeds and very large storage capacity and memory as compared to minicomputers. These computers even possess and work with more than one processor at the same time. Thus one can say these are multiuser, multiprocessor systems. For mainframe computers very sophisticated operating systems are needed to control and supervise their operation.

Characteristics and Uses of Minicomputers. Mainframe computers, and Supercomputers

Q31. Identify and discuss characteristics and uses of

(a) Minicomputers

(b) Mainframe computers, and

(c) Supercomputers.

Ans(a). Minicomputers

Minicomputers, also called mid-range servers, are more powerful computers than micro-computers in terms of processing power and capabilities. Minicomputers are mainly multiuser systems where many users simultaneously work on the systems. Mini computers possess greater storage capacity and larger memories as compared to microcomputers. These are even capable of handling more input-output devices.

Examples are: PDP-11, VAX, 7500 MAGNUM etc.

 

Ans(b). Mainframe Computers

Mainframe computers are designed to handle huge volumes of data and information. These can support more than hundred users at same time. These very large and expensive computers have great processing speeds and very large storage capacity and memory as compared to minicomputers. These computers even possess and work with more than one processor at the same time. Thus one can say these are multiuser, multiprocessor systems. For mainframe computers very sophisticated operating systems are needed to control and supervise their operation.

Examples are: ICL39, CDC 6600, VAX 8842, IBM 3090/600, IBM4381.

 

Ans(c). Supercomputers

Super computers are the most powerful computers among digital computers. These consist of several processors running together thereby making them immensely faster and powerful. These computers are capable of handling huge amounts of calculations that are beyond human capabilities. Super computers can perform billions of instructions per second. Some of the today’s super computers have the computing capability equal to that of 40,000 micro computers. A Japanese super-computer has calculated the value of Pi (π) to 16 million decimal places. These are mainly used in application like weather forecasting, nuclear science research, aerodynamic modeling, seismology, metrology etc.

Examples are: CRAY X-MP-14, CDC-205, ETA GF-10, FUJITSU VP-400, NEC SX-2, PARAM, PACE.

 

Microcomputer different from the other Computers

Q29. How is the microcomputer different from the other computers?

Ans. A microcomputer is a computer whose CPU is a microprocessor. A microprocessor is a processor whose all components are on a single integrated-circuit chip. Those are normally single-microprocessor, single-user systems designed for performing basic operations like educational, training, small business applications, playing games etc.

Computers Classification

Q28. How are computers classified? How are they different from one another?

Ans. The computers have been classified into three categories. These are given below:

  1. Digital Computers
  2. Analog Computers
  3. Hybrid Computers

Digital Computer

A computer that deals with discrete quantities. It counts rather than measuring.

Analog Computer

A computer that deals with physical quantities. It measures rather than counting.

Hybrid Computer

A computer that combines the characteristics of analog and digital computers.

 

How are the computers of four different generations superior as compared to their previous models

Q27. How are the computers of four different generations superior as compared to their previous models?

Ans. First Generation Computers (1949-55)

The first generation computers used thermionic values (vacuum tubes) and machine language was used for giving instructions. The first generation computers used the concept of ‘stored program’. The computers of their generation were very large in size and their programming was a difficult task.

 

The first generation computers suffered from some ‘big’ limitations like slow operating speed, restricted computing capacity, high power consumption, short mean time between failures, very large space requirement and limited programming capabilities.

Further researches in this line aimed at removal of these limitations.

 

Second Generation Computers (1956-65)

A big revolution in electronics took place with the invention of transistors. Transistors were highly reliable compared to tubes. They occupied less space and required only 1/10 of the power required by tubes. Also they took 1/10 time (switching from 1 to 1 or 1 to 0 ) needed by tubes and were ten times cheaper than those using tubes.

 

Another major event during this period was the invention of magnetic core for storage. Magnetic cores were used to construct large random access memories. These new developments made these computers much more reliable and paved the way for the development of high level language (HLL).

 

With speedy CPUs and the advent of magnetic tape and disk storage, operating systems came into being.

 

Third Generation Computers (1966-75)

The third generation’s computers replaced transistors with ‘Integrated Circuits’ known popularly as chips.

The third generation computers using integrated circuits proved to be highly reliable, relatively inexpensive, and faster. Less human labor was required at assembly stage.

 

Fourth Generation Computers (1976-present)

The advent of the microprocessor chip marked the beginning of the fourth generation computers. The emergence of the microprocessor (CPU on a single chip) led to the emergence of extremely powerful personal computers. Computers costs came down rapidly. The faster accessing and processing speeds and increased memory capacity helped in development of much more powerful operating systems.