Understanding the importance of ECA’s(Extra Curricular activities) of student, Department of Business Studies arranged the event “Talent Hunt & 2nd Inter Batch Debate Competition 2010” .
It is truly a great moment for Department of Business Studies.
“It’s time to show” with this Slogan we have started our journey to make this event successful.
Our enthusiast faculty members from school of business spare their valuable time to short list 10 student among 60 participants.
Today those 10 finalists will perform from different category and among them our celebrity judges and the panelist will select 3 Best Entertainer.
Today we are dedicating all our performance to those ‘WOMEN’ Unable to bear the insults and have committed suicide.
It is a pleasure to announce today’s event is directly telecasted by our media partner Radio Amar FM 88.00 and the whole ceremony will be livecasted by Comjagat.com on its website

Originally Published on Computer Jagat Magazine

M. Shorif Uddin*  and   M. Sarowar*

1.   Introduction:

Generally, a real time system is a real time program that is very like a non-sequential program. It has to manage peripherals, and follow some mechanism. But a real time program should include a supplementary issue: timing constraints imposed by the fact a real time program controls an external system. Real time applications are characterized by the strict requirements they impose on the timing behavior of the system. System ensuring that those timing requirements are met called real time systems. We will exclude transactions system (seat reservation, banking) from real time systems. Though transaction systems are done in real time, but without any strict timing constraint. A computer guided air-missile is a real time system. Current fields of applications include scientific instrumentation, medicine, industry, cars and military. For example, a real time system may drive and monitor an astronomical telescope or an X-ray medical scanner, control an industrial production line or a car motor and air navigation systems, as well as drive a weapon delivery system or control an entire nuclear power plant.

Timing and controls are the master words in the real time systems world. In general, any system meeting external constraints and able to solve these constraints during its execution, without any specification on the architecture of the system, is a real time system.

Real time system may be divided in two groups. The hard real time system for which a failure to meeting the timing constraints is considered as a major failure or crash of the system. Others can tolerate that means will give an error or warning on such failure, without stopping are called soft real time system.

2.    Implementation Issues:

To program a real time system, we need a programming language that gives the facilities to handle the timing constraint imposed by the system provides real time Input-Output access. For multi-machines real time applications, operating system is a real problem. The traditional approach to multitasking operating system design is to split the time in slices and to attribute those slices to the different computing resources demanding applications. This kind of management is called time sharing. Time sharing does not address correcting the problems art sing in real time system. So, the execution of the real time applications has to be supported by correct environment, which is obtained through a real time operating system. These real time operating systems have to manage timing and interactions problems. Different mechanisms allow them to handle timing constraints correctly. They also contain mechanisms to solve the process scheduling problems. Another aspect treats the communications between’ tasks, with semaphores (allow unrelated process to synchronize execution) and shared data zones.

3.   About time:

Time handling is the most important issue in the real time systems. Time handling includes: Knowledge of the time, Time representation concepts, Time constraints representation.

Time is given by clocks. A clock is characterized by its correctness, which defines the quality of the knowledge of time, and by its accuracy, which defines the way the clock drifts.

A standard clock is one for which the relation is: C(t) = t, confirmed.

A clock is correct at the time t0, if C(t0) = to.

A clock is accurate at time to, if

dC(t)
____    =l,at t=t₀
dt

Time representation in real time systems should be sufficiently well-designed to take into account the properties of the system, and to allow a precise definition of the characteristics of the time constraints. Each characteristics operating system uses a system clock to manage the timing synchronization between processes. This clock gives interrupts to the system at a certain rate that can usually be modified and duration about some tens of milliseconds. This gives the granularity for scheduling process.

There is another. Clock used for time measurement, which can also be used to drive a programmable timer for scheduling events at certain time. This is called the real time clock and has a granularity of < about microseconds. A real time operating system will usually use this clock to synchronize the processes or manage timing constraints. A real time system has to deal with the arrival of time constraint requests, i.e. the invocation of processes to be executed in due time.

The system has to allocate the resources to meet specifications, in order that the process can begin at a specified time, and be completed at another specified time. The minimum definition of a timing constraint is the triple (three variable):

(Id, T begin ^{(condition 1)},

Tend ^{(Condition 2)}

Where, Id is the name or number of the process

Tbegin (condition 1) is the starting time of the process.

Tend (condition2) is the completion time of the process.

Time constraint synchronization mechanism is another important issue in real time systems. One of the popular synchronization mechanism is interrupt driven mechanism. An interrupt is a signal occurring synchronously and triggering a service routine. This service routine is called by the interrupt handler, which identifies the interrupt, and executes appropriate routine. The routine has to be carefully designed to meet the time constraints on its duration, deadline and frequency.

4.   Design Issues:

The design of any system should begin by a requirement specification phase, followed by a design phase itself. These phases will be followed by implementation phase, testing, etc. The design phase can also be decomposed in a preliminary and detail phase. The different phases and sub-phases may overlap each other in time.

Real time systems can not be programmed with traditional operating system. ‘Ada’ and ‘Pearl’ are the high-level real time languages used in industrial control environments because these have been implemented on a wide range of computers. More over, real time systems can be programmed with classical C languages if there is a library of functions implementing the real time mechanisms.

‘Portos’ (Portable real time operating system) is the most fascinating real time operating system dedicated to real time applications for personal computers. ‘Portos’ controls the execution of application programs written in ‘Pearl’, ‘Ada’ and C. ‘Portos’ can be installed in all conventional microprocessor-based personal computers such as IBM PC-XT, IBM PC-AT. Memory requirements of ‘Protos’ depend on application programs. Normally, ‘Portos’ needs memory of 4-100 KB. Performance measurement of a real time operating system depends on the time requirement to react to external events. On an IBM-AT, ‘Portos’ ensures the processing of interrupts within less than 20 ms.

5.   Conclusion:

The importance of real time systems is rapidly growing. Such systems are highly promising for well being of people. In today’s competitive world, the prosperity of nations are now depending on the application and efficient utilization of computer integrated manufacturing systems,  of which real time systems are an essential and decisive part.

We hope that our future system engineers will engage themselves in research, development and application real time systems and thus be able to effectively^ strengthen the industries of our country.

References:

[1] Paul Bartholdi—Denis Megevand, “Software Design” in College on Microprocessor-Based Real Time Control, ICTP, Trieste, Italy, September 1994.

[2] Wolfgang A. Halang, “A curriculum for real time computer and control systems engineering”, IEEE Transactions on Education, Vol. 33, No. 2, May 1990.

* Asst. Prof. Department of Electronics and Computer Science

Jahangirnagar University.

** Lecturer Department of Electronics and Computer Science

Jahangirnagar University.

Originally Published in Computer Jagat Magazine

MD. AL-AMIN BHUIYAN

As the world’s economy grows, more and more data is produced. This has created an ever increasing demand for faster data communications locally, nationally and globally. Data communication thus emerged as a natural result of the development of sophisticated computer systems— it has become the milestone in the today’s information explosion age.

1. COMPUTER COMMUNICATION OVER TELEPHONE LINES:

Computers are used to generate and process information. But generated information is not useful in itself. Sometimes it is necessary to transfer this information from one place to another. Data communication is the transfer of data or information between computer devices.

In the middle of nineteenth century data communication used to take place mostly through telegraph cables using Morse Code. However, with the beginning of computer era, the need to send data from one point to another with greater speed and efficiency arose. Also as the computer industry began to grow faster, the better and speedier were the computers. Under this condition, data communications have continued to change dramatically.

A direct link between the computers could send data between them, but problem arises when the sending and receiving computers are placed at remote distances. Because digital signals, when transmitted over long distances, suffer severe distortion. Also it is an impractical plus very expensive idea to join all sending and receiving computers, via cables. Data maybe transferred from one computer to another at remote distances over telephone lines, coaxial cables, wave guides, or over satellite communications. Since telephone lines already have a wide network, the logical choice of transmission medium for data communication becomes the telephone lines. However, data processed by computers are in the parallel form to reduce time and increase speed, whereas, the signal through a telephone line is in serial form. Moreover, computers process data as digital signals that are either on or off, i.e. in binary form at a speed more than 1MHz. On the contrary, telephone signals are continuously rising and falling, i.e., truly are analog signals in the frequency range of 300 to 3500 Hz. Therefore, some sort of conversion must take place for data to be effectively passed from the computer over the telephone lines and this conversion is performed by two devices— Asynchronous Communication Interface Adapter (ACIA) and ‘Modem’.

The ACIA, connected to the outside world via a D-shaped 25-pin connector and built into every computer, takes parallel data from the computer’s bus and turns it into serial bit-stream and vice-versa. And modem modulates the digital signals at the transmitter, thereby rendering them suitable for transmission over telephone lines and recovers the original digital signals at the receiving end by demodulation.

2. WHAT IS A MODEM?

The name “Modem” has been derived from two words Modulator and DEModulator. Ampdem performs the function of modulation and demodulation as the name implies. That is the function of the modem is to convert digital data signals to suitable audio signals compatible with transmission lines on the transmitting end, a process referred to as modulation. Also it converts the audio signals back into digital data at the receiving end by demodulation.

If data is to be transmitted over telephone lines, the signals must be converted to reside with in the audio frequency spectrum from 300, to 3500 Hz. Modems have been developed to provide this function.

When two computers are communicating, they send information back and forth. If these two computers are within a reasonable distance, they can send and receive information through a direct cable connection, which is sometimes called a null modem connection. The further the distance the signal has to travel, the greater the chance that some information will be lost. For this reason, in a direct cable connection, it is generally recommended that the computers be within 50 meters of each other.

Computers can exchange information over telephone lines by using two modems—one on each side, a calling computer (or a terminal) contacts a receiving computer through a telephone number, and a communication link is established after control signals have been exchanged between computers and modems.

3.  DATA COMMUNICATION SYSTEM:

A data communication system, providing electronic distribution of information from computer to computer consists of five basic components. These basic components are:

(a)    The sending or originating computer: The originating computer or terminal has data to transmit. The data may consist of a file on a disk or may be entered into a keyboard, transmitted as it is typed.

(b)    Data Communication device Attached to the sending computer:

The data communication device attached to the sending computer converts the data into a form that can be transmitted.

(c)    Communication Channel:

The communication channel (also called a communication link) carries the data being carried from place to place. There are many possible communication channels, including telephone lines, coaxial cables, optical fibre systems or microwave relay systems.

(d)    Data Communication Device Attached to the Receiving Device:

The data communication device attached to the receiving computer converts the transmitted data into a form so that the receiving computer can understand.

(e)    Receiving Computer:

The receiving computer or terminal receives the data and displays them on a screen, prints them, or stores them in a file.

4.  MANAGING THE COMMUNICATION LINK:

All communications between computers are managed by data communication software. The précised procedures used for communication depend on the particular software; some general procedures are listed below:

I. Communication between two Microcomputers:

The procedure used to communicate between two microcomputers is as follows:

(A)    Both the microcomputer user start the communication program, which gives them a menu of options.

(B)    Both the user choose the same options, including the number of start and stop bits, the type of parity checking, the communication rate, full-duplex or half-duplex transmission, and so on.

(C)    Before establishing the communication link, the users decide who will originate the telephone call. The originator enters the telephone number. The communication program then instructs the modem to dial the number, and the program reports the users whether the connection has been established.

(D) After the connection has established, the users can have an on-line conversation. The can type messages back and forth to each other and also record their conversation.

(E)    When a user is ready to transfer files, he or she sets his or her computer to send; the called user sets his or her computer to receive. The communication program takes over by reading the information from the disk and sends it through the communication link, the receiving computer stores the incoming information on a disk and also can display on its screen.

(F)    When the transfer has been completed, the users say “goodbye” and terminate the connection.

2:         Communication between a microcomputer and a Mainframe Computer:

The procedure for communication between a microcomputer and a minicomputer or a mainframe computer is similar. One difference is that the big computers have safe guards that limit access to files and facilities to authorized users. The most common safeguards are user identification number and password.

After the communication link has been established, the receiving computer asks for the user’s identification number. The microcomputer user sends the identification number, after which the receiving computer checks whether the identification number is valid. It then asks for the user’s password.

A password is a confidential sequence of characters that allows access to the system. It is required for the user to obtain access to the mainframe computer. It also determines exactly which files and facilities the microcomputer user is allowed to read.

5. DATA TRANSMISSION MODES:

Once a communication link has been established between two points, it can be used in one of three communication modes. The modes are Simplex, Half Duplex, and Full Duplex.

Simplex transmission is that transmission which occurs in one direction only. In a simplex transmission mode, one device is always a transmitter and the other device is a receiver.

Half-duplex transmission permits trans­mission in either direction; however, trans­mission can occur in only one direction at a time. Thus at any instant, if one device acts as a transmitter, the other acts as a receiver and vice-versa.

Full-duplex allows data transfer in devices simultaneously. Thus one device may be transmitting and receiving simultaneously while the other does the same. The two simultaneous transmissions may or may not be related and occur on two separate and distinct communication channels.

The communication mode to be chosen may be the result of communication medium limitations, hardware usage or programming conventions.

Most of the present day modems offer half-duplex, full duplex or both facilities. Simplex is not used with modems.

6. TRANSMISSION TECHNIQUES:

Data generated by computer is normally character oriented and is outputted in serial form as a series of equal duration bits. This generated data is transmitted between different communicating points. However, some sort of information is usually required as to how the data will be transmitted. There are two methods of doing this and these are referred to as synchronous and asynchronous transmission.

Synchronous Transmission:

In synchronous transmission, characters are transmitted as groups, preceded and followed by control characters. In synchronous communication, data bytes are sent one after another at regular intervals. The data form as continuous stream of bits spaced at regular intervals, with no space between consecutive bytes. A timing mechanism causes the receiving modem to read the stream at precisely the correct frequency. When the receiving modem has read the required number of bits to makeup a character, it sends the character to the receiving computer.

In this type of transmission, since data is sent as a block of characters, both transmitter and receiver need to have buffers for storing block of characters, a major advantage of using this transmission technique is high speed. Since fewer bits are needed to identify the beginning and end of character coding. Again, as there is no gap between characters, precise data space is not wasted. Its chief drawback is inaccuracy; when a receiver goes out of synchronization, losing track of where individual character begin and end, correction of errors takes additional time. Synchronous transmission is used when data rate over 2400 bauds is required.

Asynchronous Transmission:

In asynchronous transmission, each character is transmitted separately, that is, one character at a time. The character is preceded by a start bit, which is always a ‘O’ (zero) that tells the receiving device where the character coding begins, then five to eight bits-representing the actual information being transmitted, an optional parity bit (even or odd parity) for error detection capability and is followed by 1, 1F(1,2), or 2 stop bits, which tells the receiving device where the character coding ends, after which is an interval of time on the channel. Then the next character is sent, start bit first, character’s bits next, stop bit(s) lactates, allow the receiving and sending computers to synchronize the transmission. This is the most common technique of data transmission worldwide. Its principal advantage is accuracy, while its main drawback is slow transmission speed caused by the great number of start and stop bits. Asynchronous communication is typically used at communication rates lower than 2400 bauds.

7. SERIAL COMMUNICATIONS PARAMETERS:

There are several parameters governing how serial communications data is formatted. The most common serial communications parameters that will encounter are the baud rate, the number of data bits per word, parity, and the number of stop bits.

Baud rate: “Baud rate” is the speed at which data is transmitted. This parameter, also referred to as bits per second, bit rate, or data rate, typically ranges from 300 to 9600 baud.

Number of Data Bits: The “number of data bits” refers to the number of bits that constitutes one data word. In serial communications, each data word is transmitted as a sequence of bits. This word may be immediately preceded or followed by other bits (parity or start and stop bits) that are used for controlling the communication. The number of stop bits is variable; the default is one.

Parity: Parity is a method for detecting errors in data communications. The parity bit is added at the end of data word, the value of this bit is a function of the rest of the data word. “Even parity” means that the parity bit is set so that the sum of all the bits in the data word (including the parity bit) is even and “odd parity” means that the parity bit is so set that the sum of all bits is two stop bits are added to the end of a data word, these bits tell the receiver where the end of each data word is number. “Mark parity” means that the parity bit is always a 1; “Space parity” means that the parity bit is always a 0. “No parity” means that no parity bit is added to the end of a data word.

Stop Bits: In asynchronous serial com­munications, either one, one and a half, or two stop bits are added to the end of a data word, these bits tell the receiver where the end of each data word is.

8. DTE-DCE INTERFACE:

In the world of data communications, equipment that includes terminal and computer ports is referred to as Data Terminal Equipment or DTE. In comparison, modems and other communication devices are referred to as Data Communications Equipment or DCE.

The physical, electrical and logical rules for the exchange of data between DTEs and DCEs are specified by interface standards; the most commonly used is the EIA RS-232C standard. The RS-232C specifies the use of D-shaped 25-pin interface connector.

9.  RS-232C SERIAL COMMUNICATION STANDARD:

When one computer communicates with another over long distances, the data are transmitted serially. Internally, computers almost universally use data in parallel form. Therefore, this parallel data must be transferred into a serial form before being send through telephone lines and after reception the data string must be recomposed into parallel form. Most personal computers, however, has fitted with them a serial interface through which modems are used to send serial data.

At present, three types of standard are followed in case of modems. These are:

Bell Standard, EIA (Electronics Industries Association) standard and CCITT standard. Of these, the RS-232C standard, issued by EIA, is perhaps of the most interest to the hobbyist or microcomputer users. It defines all the features of communication, that is, the number of pins in the connection, the dimension and construction of the connector, the signal levels on the pins, the interrelationship between the signals and the procedure for exchanging information. This so-called DB-25 connector is, there­fore, widely used for communication pur­poses. RS-232C is a recommended stand­ard (RS) published by the Electronics In­dustries Association (EIA) in 1969, with the number 232 referencing the identification number of one particular communication standard and the suffix C identifies the current revision level. It specifies (among other things) that the marks and spaces that make up the code must be of certain amplitudes.

The RS-232C voltage levels are defined as follows: Logic 1 (mark) = less negative than -3V Logic 0 (space) = more positive than + 3V Any voltage between -3V and + 3V is undefined. Typically, an RS-232C system uses nominal voltages of -12V and +12V for a ’1′ or ’0′, respectively, the more positive voltage than +15V and the more negative voltage than – 12V is also undefined.

Basically, a serial interface consists of a transmitted signal (pin 2), a received signal (pin 3), and a ground connection (pin 7). This is the barest minimum for bi-directional link. However, handshaking lines are used in addition, but are not essential. In this case, the Request to Send (pin 4), Carrier to send (pin 5), Data Terminal Ready (pin 20), Data Set Ready (pin 6), Carrier Detect (pin 8), and Ring Indicator (pin 22) lines are required, and the remainders are seldom encountered in normal practice.

APPLICATIONS OF DATA COMMUNICATION:

Data communication systems are designed to provide information flow among computers. There are variety of reasons for interlinking computers and peripherals. Some of which are outlined below:

The ability to share and exchange data between systems is a compelling reason for interconnection. Users from different locations can easily transfer information in the preparation of a document or for an analysis.

There are many applications centered on remote accessing of data bases. Simple examples are the information services and financial services available to personal computer user. More sophisticated examples, requiring many interactions between the remote site and the data base and its associated program include remote computerized medical diagnosis and remote computer aided education.

Communication, the transfer of information, is the basis of office automation. Airline reservation system, automated banking systems, inventory control systems etc. provide a number of examples.

When one reserves seat on an airplane, the agent enters the reservation on a terminal connected to the airline’s computer. Since the computer is usually located far from the agent (sometimes several thousand miles away), data communication must be used to relay data from the terminal to the computer and back from the computer to the terminal.

Most banks now provide a wide range of banking services through automatic teller machines (ATM‘s). Users can make deposits and withdrawals, cheek balances, and even pay utility bills through the machines. An automatic teller machine is connected to the bank’s main computer, which may be located at another end of the city or even in another state. The transaction request is sent to the computer using a data communication system.

Many retail stores use point of sale terminals instead of cash register. These terminals send records of sales to a central computer, which maintains accounting and inventory records.

Another popular application is the electronic mail. Such a mail can be read, filed, forwarded to other individuals, with added comments or read by the addresses at different locations. Obviously, such a service has many advantages over postal mail in terms of delivery speed and flexibility. It has also advantages over voice telephone service in terms of providing a record, reducing cost (for long distance calls), and eliminating the need for both users to communicate at the same time.

CONCLUSION:

The proliferation of computers has caused an “information explosion”. As time goes by we hear more and more about public services that will make computers and giant data bases available to every home. This information explosion has instigated the computer communication to become one of the most widely expanding field of research area. With technological innovations different types of signals (e.g. computer data, human voice, audio, video, information) are now transmitted through the same communication channel, and computer communications are extensively used for this purpose.

With the wide spread use of computers in Bangladesh, the necessity of communicating and transmitting data from place to place becomes inevitable day by day. There are some Electronics and Computer firms communicating with U.S.A. England, Singapore and Japan, have installed modems with their personal computers. But these modems, however, are very expensive. To overcome this difficulty, modems should be designed and communication software be developed here which could be used in scientific, industrial, educational institutions or in office applications in our country for realizing greater potential of computer usage.

* MD. AL-AMIN BHUIYAN

Lecturer, Dept. of Electronics &

Computer Science,

University of Jahangimagar.

Reference :

1.   MD. Al-Amin Bhuyan. “Implementation of Data Communication over Telephone Lines” M.Sc (Thesis). Dept. of Applied Physics & Electronics. Dhaka University. 1992.

2.   MD. Al-Amin Bhuyan & Jalalur Rahaman, “Design and Development of an FSK modem for Data Communication”, Vol. 2, No. 1 1992. Journal of Bangladesh Electronics Society.

3.   C. Mohen. “Telecomputing the rightway,” Electronics foryou, Vol. 23, No.4, ApriU991.

4.   S.  K.  Basandra.  “Data Communication”. Electronics foryou, Vol. 23. No.4. April 1991.

5.   A. S. B. Raj, “Modem,” Practical Electronics. Vol. 21. No. 6, June. 1985.

6.   M. Tooley and D. Whitfield, “Modems”, Practical Electronics Vol.21. No. 6, June 1985.

Compaq Computer’s Singapore Factory has shipped more than one million PCs in 1994 , a remarkable achievement considering that the group as a whole shipped less than this two years ago— said Compaq Asia Vice-President and Managing Director Kirl Moul.

On the eve of first evening ministerial factory visit by Singapore’s Trade & Industry Minister Yeo Cheow Tong on 15th December, 1994 Mr. Moul said this to the accompanying reporters.

Mr. Moul said, “The Singapore Plant is a major contributor to our worldwide operations, and we expect to do even better when our new plant is ready in 1996.”

He disclosed that raw material and component sourcing by Singapore-based Compaq Asia surpassed the US$ 1 billion mark annually,

Compaq, the world number one PC seller has five production facilities worldwide, the most recent additions being one in Mexico and another is Shenzhea (China).

“More than two-thirds of what we purchase for our production operations are from the Asia-Pacific region of which about 9% is from Singapore,” said Mr. Moul.

Mr. Yeo said, “We must maintain our competitive edge. We have to encourage more local companies to improve their process technology, and to work more closely with the multinational corporations (MNCs) like Compaq for technology transfers.” He cited Compaq as an MNC that has succeeded in tapping Singapore’s skilled manpower and competitive advantage to compete effectively in the fast changing PC industry.

Mr. Moul said, ” Time-to-market is crucial in this industry, and Singapore’s excellent infrastructure ensures that this is possible.” Asked if Singapore would lose out to neighboring low-cost countries, Mr. Yeo said, “We must concentrate on improving on high-tech capabilities. Ultimately, we just can’t afford to keep the low-tech, labour intensive operations here anyway.”

[ Compiled by—Azam Mahmod ]

Kazi Sayeda Momtaz (Sharmin)

The well known word “system” is comes from the Greek word “systema” which indicates an organized relationship among functioning units. A system exists because it is designed to achieve one or more objectives. So, a system is a set of components that act as an organic whole. In the context of programming, a system is an integrated collection of programs and data files that act as a unit. The purpose of the system is normally to process information. The output of the system is information. The input to the system is information provided by the user.

Systems have been classified in different ways. Common classifications are: (a) physical or abstract, (b) open or closed, (c) “man-made” information systems.

User area —> Systems analysis —> Programming Operations

Interdependence in a computer based system

We are familiar with various types of systems. Some of them are contained within the human body, such as the digestive and nervous systems. Some are the result of ideas, thoughts or philosophies, such as the judicial system, the democratic system and the language systems. Some provide the means of distributing some useful commodity, such as transportation systems, communication systems and electric power systems. In business, we refer to accounting, inventory, and marketing systems. Indeed, the entire universe is the most magnificent, complex, and powerful system of all.

We can recognize certain characteristics that seem to be common among most if not all systems. First, systems are made up of different parts, or components. Second, the parts are related and have definite interactions or interdependencies. Third, a change any of the components is likely to produce some sort of change in other components and in the system as a whole. Fourth, the components all work toward some particular purpose or function which is the primary object of the system as a whole. Fifth, the system usually is complex, having diverse components such as persons, ideas, materials, forces, procedures and other factors. Sixth .each system is likely to be divided into many subsystems. Further, there seems to be an infinite number of relationships possible between systems of all types.

Now components may be simple or complex, basic or advanced. They may be a single computer with a keyboard.

Memory and printer or a series of intelligent terminals linked to a mainframe. It either case, each component is part of the total system and has to do its share of work for the system to achieve the intended goal. This orientation requires an orderly grouping of the components for the design of a successful system. Interaction refers to the manner in which each component functions with other components of the system. In a computer system, the central processing unit must interact with the input device to solve a problem. In turn, the main memory holds programs and data that the arithmetic unit uses for computation. So, the interrelationship between these components enables the computer to perform. Again, interdependence means that parts of the organization or computer system depend on one another. They are coordinated and linked together according to a plan. So, the output of one subsystem is the required input for another subsystem.

Lastly, we can freely speak that a system is concerned with a function or purpose, and each person thinks in terms of the job he/she is trying to accomplish.

So, no subsystem can function in isolation because it is dependent on the inputs and it receives from other subsystems to perform its required tasks. Interdependence is further illustrated by the activities and support of systems analysts, programmers, and the operations staff in a computer center. A decision to computerize an application is initiated by the user, analyzed and designed by the analyst, programmed and tested by the programmer, and run by the computer operator. As shown in figure, none of these persons can perform properly without the required input from others.

Systems analysis is the formal study and evaluation of activities and procedures. The results of this kind of study form the foundation for managerial decisions and should therefore be presented in formalized and standardized form. Systems analysis implies the examination of each component part of the system, both as a separate entity and in relation to the whole.

Systems analysis leads logically to systems design, which is the creative act of division or inventing a partially or completely new chime for processing data.

Thus systems analysis may be defined as an analytical study that helps a decision maker to identify and select a preferred course of action among several feasible alternatives. It is a logical and systematic approach where in assumptions, objectives and criteria are clearly defined and specified. It can significantly aid a decision maker to arrive at better decisions by broadening his/her information base, by providing a better understanding of the system and interlink ages of the various subsystems, by predicting the consequences of several alternative courses of action, or by selecting a suitable course of action that will accomplish a prescribed result. Systems analysis has added a totally new dimension to the science of policy-planning and decisions-making.

Systems analysis provides the answer by methods and techniques that are available to every one for critical analysis and examination. These are not unique in the sense that anyone who has the necessary expertise and experience can exactly duplicate the analysis. The models developed can be constantly updated as more information becomes available. In contrast to other available decision-making tools that have the same limitations, systems analysis uses all the relevant information available and extracts the best components from different disciplines on which the analysis are based. Thus virtues of systems analysis are also virtues of the methods and techniques on which it is based.

Mainly the primary object of the analysis is to study the problem prior to taking action. There are four main goals of the analysis such as:

1. To define the goal or goals of the system

2. To document the goals in such a way that success of the system can later be measured.

3. To predict relevant specifications such as costs, benefits schedules and performances characteristics

4.  To obtain user concurrence for each of the proceding three objectives.

As for example, for our general ledger system, the primary goal is the income report and balance sheet for each period.

In most cases, systems analysis operate in a dynamic environment where change is a way of life. The environment may be a business firm, a business application or a computer system. To reconstruct a system, the analyst must consider its elements such as outputs and inputs, processors, control, feedback, and environment.

In a concluding part we can say that the difference between a good system and a bad one is that the good system will provide a service in a more effective, economical, timely or safer manner. The bad system may provide the equivalent service, but at a higher cost or with less comfort. It is, therefore, at this point that effective cost control should be applied initially. In many applications this is called cost effectiveness, and the systems analyst speaks of a cost effectiveness or a cost-benefit analysis.

Originally published in Computer Jagat magazine in January ,1995

Dr. Khan Monzoor-E-Khoda  and Professor D.J. Evans

SUMMARY

Due to computer word length incompatibility the UNIX clock subroutine can give incorrect times for computations exceeding 2147 sees.

In this short note a reliable UNIX clock subroutine is proposed that will return the correct time for longer running processes.

KEYWORDS : C function clock, UNIX, wrap around.

INTRODUCTION

The C function clock (see man clock, appendix 1) in the UNIX operating system usually returns the execution time of a process since its last call. However the value returned by clock( ) is defined in microseconds for compatibility with systems that have CPU clocks with much higher resolution.’ Because of this, the value returned will wrap around after accumulating only 2147 seconds of CPU time. Thus the clock( ) is only reliable up to approximately 36 minutes. To rectify this situation, an optimized subroutine is proposed in this note for an efficient reliable clock to read the CPU time used. The reliability of this new clock subroutine is also observed by comparison with the usual clock () subroutine.

DESCRIPTION OF THE NEW MODIFIED CLOCK SUBROUTINE

The new modified clock subroutine is used to read the computer’s clock to provide the amount of processor time in seconds used by a program or algorithm when it is being executed. In fact, it returns a single precision float number representing the number of seconds that process takes. Notice that the time reported is the sum of the total user times and the total system times of the calling process. Child process times are not considered as most of the users do not spawn any child process / es. When called from PASCAL or FORTRAN language, float is equivalent to data type ‘real’. An error is indicated when-1 is returned.

The structure of the subroutine depends totally on times (see man times) and is developed in the C language under the UNIX environment. Its resolution varies depending on the hardware and on the software configuration.

USER INTERFACE

To measure the execution time of a full or portion of a program, call the modified clock subroutine at the beginning of the program segment and then call it once again at the end of the segment, and then subtract the two values. The standard calling statement is defined by,

X <— mod_clock()

Where <— denotes the usual assignment statement depending on the programming language being considered. The subroutine mod_clock() must be declared as an external subroutine at the beginning of the program which calls it.

The corresponding function declaration

extern float mod_clock();

function mod_clock: real; external C;

External mod_clock

need to be used when the calling program is written

using the C, PASCAL and FORTRAN language respectively.

PROGRAM LISTING

# include <sys/types.h>

# include <sys/times.h>

# define HP_HZ    100 /”For AT &T HP UNIX*/

# define SUN_HZ 60  /*FOR MOST OTHER UNIX’/ float mod_clock()

(

struct tms zl; long 1, error_signal; float d,x;

error_signal = times (&zl); if (error_signal !=-l)|

1 = zl.tms_utim + zl.tms_stime;

x = HP_HZ (orSUN_HZ)

d = (float)l/x

else

return(d);

d = -1.0;

CONCLUSIONS

We have used a 32-bit arithmetic, floating point, HP 9000/ 870 computer system at Loughborough University of Technology to compare the efficiency and reliability of the proposed new modified clock with those of the original clock( ), (see Appendix 2).

The new modified clock subroutine is found to be considerably more reliable than the original clock subroutine when the execution time exceeds 2147 seconds (approx. 36 minutes). In fact both clock subroutines performed equivalently up to 2147 seconds.

APPENDIX 1

Clock(3C)

NAME

clock-report CPU time used

SYNOPSIS

# include <time.h>

clock_t clock(void);

DESCRIPTION

clock returns the amount of CPU time (in microseconds) used since the first call to clock. The time reported is the sum of the user and system times of the calling process and its terminated child processes for which it has executed wait(2) or system OS). To determine the time in seconds, the value returned by the clock function should be devided by the value of the macro CLOCKS_PER_SEC.

The resolution of the clock varies, depending on the hardware and on the software configuration.

If the processor time used is not available or its value cannot be represented, the function returns the value (clock_t)-1.

WARNINGS

The value returned by clock is denned in microseconds for compatibility with systems that have CPU clocks with much higher resolution. Because of this, the value returned will wrap around after accumulating only 2147 seconds of CPU time (about 36 minutes).

DEPENDENCIES

series 300 / 400

the   clock   resolution   is   20 milliseconds.

Series 700 / 800

the default clock resolution is 10 milliseconds.

SEE ALSO

times(2), wait(2), system(3S).

STANDARDS CONFORMANCE

clock: SVID2, XPG2, XPG3, ANSI C.

APPENDIX 2

Table 1: Comparison of original clock and modified clock

* Present address: Analyst, Management Information System, The Hospitality Group Ltd., 980 Young Street, Suit 200, Ontario, L5A 1H4, Canada (E-mail:khan.khoda@canrem.com.

* * Present address: Director, Parallel Algorithms Research Centre, Dept. of Computer Studies, University of Technology, Loughborough, Leicestershire, LEI 1 3TU, U.K.

Originaly Published in Computer Jagat Magazine in September 1994

Mr. Arun Krishnaswamy, Country Sales Manager of Acer Computer, South Asia said in an exclusive interview with Computer Jagat that Acer is aggressively seeking partnership with its local distributors in the areas of warranty, price, service, logistics and advertisement. The prime objective of this is to give Acer’s global brand local touch taking into consideration the local needs.

He said that this new approach is based on mutual trust and local distributors shall add value to Acer’s open machines having cutting edge features. In Mexico Acer has localized its products and instantly grabbed 32% market shares. This spirit helped Acer increase its revenue by an amazing 205% in June ’94 over 1993, informed Singapore based Arun.

Arun said that Acer do not like to duplicate the functions that can be better looked after by our local partners and Acer want them to concentrate seriously on certain areas. This synergy shall hone both the parties skill and ensure better global leverage. “It is no threat for any of us and it won’t weaken the synergy” said Arun.

“To face the challenge of new IT age Acer, a growing conglomerate of individual technology providing companies shall aggressively keep this relationship closer and closer”, said an equally aggressive and personable marketing executive Arun.

Replying on potentiality of Bangladesh market, Arun expressed his firm optimism as to future growth, of market and informed that with satisfactory performance of Acer’s high-profile local dealers— Dolphin computers and UnidevComputers, Acer shall continue to focus on solution based. Corporate and Garments Industry niches. “Development of advanced product that benefit consumers has always been Acer’s goal”, said Arun.

Since its founding in 1976 with only 11 employees, the Acer group has grown into a major computer, peripheral    and    component

supplier in the world. Arun said that with Acer’s own technology of bridging the chipset, the only Server based on Intel’s advanced Pentium that is working now in Singapore is Acer Pentium 90 Servers.

At present in Asia-Ocenia, Acer has its own subsidiaries in Malaysia, Singapore, Taiwan, Japan and Australia. Acer is also a major global competitor in Mother Board, BIOS, Cache controller cards, I.O. controller, ASIC, DRAM chip, Facsimile Machine market. These in-house access to a full range of technologies established Acer in a leading position, said Arun. He asserted, “For these unique advantage Acer brand products fetch money’s best value for the buyers and that put Acer brand among top 10 brands of PCs in the USA.”

Arun said, “The much acclaimed Acer state-of-the-art hardware fetching orders from Japanese companies to make hardwares for their machines lately and more than half of the PCs of the world have some of the Acer brand components in them.” Arun continued, “Our USA subsidiary is doing fairly good business because cost leveraging is better there.”

Arun also informed that Acer is the leading brand in Third World countries and positioned itself as No.l company in Indonesia, Malaysia, Phillipines and Thailand in PC, Server and Notebook sales.

Replying on response as to Acer’s praise-worthy introduction of International Travellers Warranty (ITW) program for its Notebook PCs. Arun said, “The portable nature of notebook PCs, results in a large number of these PCs being taken to areas where the product is not covered by a warranty. As part of our policy to provide the best possible service we introduced this program in January 1993 and almost 5,000 Acer Notebook owners from around the world have applied for an ITW warranty card so far.”

Informing about Acer’s global expansion Arun said that a joint venture semiconductor plant with Texas Instruments which is one of the world’s ten largest wafer fabs that currently produces 4MB DRAM chips in Taiwan’s Hsinchu Science based Industrial Park, and is expanding into production of 16MB DRAM chips in 1995.

In recognition of the great contributions of Acer Peripherals Inc. to Malaysian economy, Datoship honours has recently been awarded to Acer’s founder and chairman Stan Shih by Penang Governor Seri (Dr.) Hajyi Hamdan Bin SeikhTahir, informed Arun.

Detailing the Acer’s much publicized Vision of 21 in the 21 st, Arun said, “By working with local partners to run the business, implementing local management and encouraging local shareholder majorities, Acer is gradually achieving its goals of becoming a “Local Touch” global brand name with over US$ 8 billion in annual revenue by the year 2000 and this continued strengthening will pave the way for a world-wide alliance of borderless global companies within the Acer Group by the 21st century. Acer will include in its ranks 21 publicly won companies, a target known in corporate and computer world as “21 in 21″.

Young and avid Acer loyalist Arun concluded,-”These Acer Group companies will continue finding effective ways to meet the challenges of the new IT age, bringing benefits to Acer’s stock holders, employees, partners and the much revered first party— Customers.”

Azam Mahmood

With this knowledge-based economy initiative by the Ministry of Agriculture, Bangladesh Government, this major achievement could rejuvenate the multi-million dollar Jute Industry. The significant benefit in upcoming years will help Bangladesh to develop new quality breeds of Jute both in terms of fibre quality and resistance to various diseases. This local talent based discovery could make Bangladesh a hub of Jute Plant Biotechnology Research in Asia and in the world.

An unique collaboration between prestigious Dhaka University graduates and faculty, researchers from the government sponsored Bangladesh Jute Research Institute and new generation of bioinformatics specialists from the private software giant DataSoft in collaboration with international research centres in Asia and US make this discovery a template that can serve an excellent example not only for Bangladesh, but also for the rest of the developing countries.

The public announcement of this major discovery and the unveiling of the high through-put technology used in this discovery including the team members of this unique consortium will be made in the 24th of Jute with an accompanying documentary movie.