DBMS packages-3

Note that with this command will have only specified the structure of the record for a file which is to contain customer data. Therefore we should have some way of loading the customer records in the CUSTLIST file. For this purpose we will have to type the following command:

 

..APPEND

With this command we get a screen which provides a blank customer record. As the name implies, this command will append a record to our CUSTLIST file. Thus, it can be used whenever we want to add one more customer to customer list. With the customer we can add product fulfillment types. Product given to customer gives them product fulfillment or order fulfillment. We can add any criteria for that.

 

In the screen provided with above command, we now type the necessary details of a customer. The names of the fields are displayed on the screen to facilitate entry of data for a customer for which we wish to create a record in CUSTLIST file. After we type in all the required details about the customer and type e get another blank record in which we can enter data about next customer and so on. When we type right at the beginning of blank record we get back to dot prompt where we can issue a new dBASE III command.

DBMS packages

In our last post we have discussed on Data Base Management System (DBMS) and today we are going to talk on DBMS packages.

 

Like other DBMS packages, dBASE III provides features for: 

1.      Creating data files on a computer.

2.      Maintaining these data files by way of providing functions for adding, deleting editing and updating a give set of data items.

3.      Generating reports based on the data files created through dBASE III

4.      Querying on those data files.

 

To develop an understanding of the features provided by dBASE III package, let us take a specific application and see how it could be implemented in dBASE III. Suppose we are operating a small business house which has 1000 customers. We are interested in maintaining a list of these customers and using this list for our day-to-day business operations. Obviously we will have to create a file which contains data about these 1000 customers. In this file there will be one record for each customer. Thus, we will have a file containing 1000 records.

DataBase Management

The dBASE III package has attained its current popularity mainly for the following reason:

 

1.      It is easy to use and is simple. Its basic features can be learned in a couple of hours.

2.      It provides a very high level language interface which is command oriented. Some people consider it a fourth generation language. In lay man’s terms, fourth generation language means it is superior to standard programming languages like BASIC, COBOL, FORTRAN and PASCAL; and it simplifies and sometimes even avoids programming in a conventional sense.

3.      Small business information systems can be easily implemented in a few days using this package. Insurance CRM or instant life insurance rates application can be implemented easily in small businesss.

4.      This package can be used as a tool to prototype large applications. Prototyping is useful for saving costs in implementing large applications. Parts of a large system may be implemented through dBASE III package to finalize specifications of what users want through the envisaged application and how these parts could possibly be implemented in their final form.

 

We will discuss some features of the DBMS packages in our next post.

APPLICATIONS SOFTWARE

Systems software available on micro-computers includes compilers interpreters for popular programming languages like BASIC, COBOL and FORTRAN. However, because of their large numbers and personal use, powerful applications software which does not require significant programming knowledge has been developed to run on personal computers. The most important categories of this software, which enables a user to autonomously utilize a personal computer are:

 

1. Data Base Management Software
2. Spreadsheet Software
3. Word Processing Software
4. Graphic Software
5. Data Communication Software

Data Base Management

Software packages called Data Base Management System (DBMS) has been developed long before micro-computers to handle the problems of maintaining and integrating large volumes of data on large machines. The most important distinguishing feature of a DBMS package on personal computers is that it provides a very high level language interface which can be learned by a user who is not a computer programmer. In a few hours, it is possible to acquire enough skill to use the basic features of DBMS packages like dBASE III which is the best selling software currently in this class.

HARDWARE

Micro-computers are structurally similar to large computers in that they have the same basic components – CPU main memory, secondary memory and input/output devices. The most popular secondary memory device are floppy disk drives and fixed disks. Floppy disks store between 140 K Bytes to 1 Mega Byte = 1024 K Bytes (MB) while hard disks store 10 MB to 40 MB.

 

The main memory is made from several chips. These may be ROM or RAM chips.  ROM (Read Only Memory) chips contain instructions permanently written in the memory. The contents of these chips cannot be altered. RAM (Random Access Memory) Chips provide the memory that can be read from, written into and cleared.

 

Most micro-computers have between 16 K bytes and IMB memory. The typical word-size of micro-computers when they were introduced in business in the late seventies was B-bits. Today, the most common word-size is 16-bits. It is virtually certain that in the next few years 32-bit micro-computers will be very common although today their numbers are somewhat limited due to cost and scarcity of software. Dot matrix and daisy-wheel printers are popular printing devices on micro-computers.

Personal Computer and its uses-1

INTRODUCTION OF PERSONAL COMPUTER AND ITS USES

Computers were first used in management and business applications in centralized data processing departments. These departments were manned by computer specialists who were the only persons allowed access to the machines. Later terminals were provided to users for certain applications. However, cost, complexity, size and the need for special environment control did not permit computer users to have computers at their work places. All this has changed with the advent of micro-computers. For example market type is also change now a day than before. New days companies are using trade show booths where they have banner stands, table skirts and pipe and drape. Same way, computers are changing day by day with the use of new technology being invented and introduced in the market. Marketing exhibitions and trades shows are best way to introduce new technology to people.

 

MICRO-COMPUTERS

Micro-computers are computers which have their entire Central Processing Unit (CPU) on single integrated circuit ‘chip’ (called a micro-processor). Today powerful micro-computers are available which cost as little as $ 500. These micro-computers can do many of the jobs earlier done by large computers which cost many times this amount. In addition, because they are small enough to sit on a desk and do not require extensive environmental control, they can be used in most reasonably dust-free environments. Field tests on machines used in projects such as the Computer Literacy Project for Secondary Schools of the Education Ministry have shown this.

 

This ready availability for users has enabled a large number of entirely new applications to be undertaken. It has also increased user interest in computing since users can be directly in control of their data unlike the situation with centralized computing. Due to these factors and the fact that micro-computers can be used at home and schools for education and entertainment there has been a spectacular increase in their numbers since their first arrival as hobby kits in the U.S. Several million micro-computers are used in management applications around the world today. In India the projections are that by 1990 a few lakhs of these machines will be installed.

Classification of Computers-1

A large computer provides a main memory capacity of up to 32 mega bytes, a processing power of 10 MIPS and supports a large number of disks and tapes. Disk capacities range from 100 MB to 1000 MB. It also allows simultaneous access to multiple users and supports a large number of input and output devices.

 

A super computer is the largest computer system available in the market. It provides a main memory capacity of up to 64 mega bytes and a processing speed of 20 MIPS. It also supports a large number of disks and tapes of enormous capacity for providing random access and serial access secondary memory. A super computer also allows multiple users to interact with the CPU simultaneously through multiple types of input devices. It also provides outputs in a variety of forms and supports a large number of output devices. Customer Relation Management System owner says that for their clients who are selling blinds, roller shades and woven wood shades online; they need to use high configuration computers.

Personal computers are used by managers for their own computing needs. Availability of a large number of user-friendly software packages on PCs have made them effective tools to support managerial decision-making. PCs have also encouraged distributed data processing. A super micro is used for commercial data processing and managerial applications. A large computer is necessary for very large data processing and data management applications. A large computer is necessary for very large data processing and data management applications. A super computer is primarily used for highly scientific and research purposes.

Classification Of Computers

 

In the 1970s computers were classified into three categories, namely, super-computers, large computers and mini computers. But the invention of the micro-processor which gave birth to micro-computers in the late 70s has drastically changed the computing scene. A wide range of computers are available today in the market ranging from a personal computer to a super computer.

 

A personal computer (PC) is a micro-computer which has its entire central processing unit on a single micro-processor chip. A PC provides a main memory capacity upto 640 kilo bytes and a processing power of 0.5 MIPS. It supports one or 2 diskette drives of 360 KB each for random access secondary memory. A PC usually comes with a standard key board, a visual display unit and a dot matrix printer. A PC is usually operated by a single user.

 

A super mico-computer has its entire central processing unit on a very powerful micro-processor, provides a main memory capacity of upto 16 mega bytes, has a processing power of 2 to 3 MIPS, supports Winchester disks of capacity 20 to 80 mega bytes and allows simultaneously access to multiple users. Today’s super micro is actually replacing yesterday’s mini computers which provide almost the same computing power it nit less, but based on a different technology.

Operating Systems-1

We are talking computers in management. We talked evaluation of computers and computer softwares in our previous talk. We talked about operating system in our last post, today we continue with that. We talked the drawback of idling the CPU was overcome with the introduction of overlapped processing.

For example why not take up input operation of job 2 and the output operation of job 1 simultaneously? This and similar considerations gave rise to the concept of multi-programming. A multi-programming operating system handles multiple jobs simultaneously by overlapping the input, output and processing cycles of various jobs.

This operating system was introduced along with third generation computers and is still very popular. It has replaced the earlier batch processing (serial) operating system. With multi-programming a CPU’s utilization is increased and hence jobs get executed faster on an average. However a multi-programming operating system is more complex hardware to support it.

Other types of operating systems which are popular today are multi-processing operating systems and real time operating systems. A multi-processing operating system uses multiple CPU’s to process multiple jobs. A real time operating system is a very different type of operating system, because it is used for different type of applications, i.e., real time applications such as airlines reservations, process control, etc.

Utilities

Utility programmes are those which are very often requested by many application programmes. mailing leads and marketing list are few example of such utility programmes which are used in large by industry. A few examples are:

SORT/MERGE for sorting large volumes of data and merging them into a single sort list like mortgage mailing list.

Transfer programmes for transforming contents from one medium to another, e.g., disk to tape, tape to disk, etc.

Operating Systems

An operating system is the most important system software and is required to operate a computer system. An operating system manages a computer’s resources very effectively, takes care of scheduling multiple jobs for execution and manages the flow of data and instructions between the input/output units and the main memory.

 

Operating systems became a part of computer software with the second generation computers. Since then operating systems have undergone several revisions and modifications in order to achieve a better utilization of computer resources. Advances in the field of computer hardware have also helped the development of more efficient operating systems.

 

The first operating system called batch processing (serial) operating system was developed for the second generation computers; This operating system executes jobs serially one after another from a batch of jobs submitted for execution. The central processing unit is kept busy only during the processing cycle of a job and it idles during the input and output operations.

 

The above drawback of idling the CPU was overcome with the introduction of overlapped processing. For example why not take up input operation of job 2 and the output operation of job 1 simultaneously? This and similar considerations gave rise to the concept of multi-programming. A multi-programming operating system handles multiple jobs simultaneously by overlapping the input, output and processing cycles of various jobs.