It Information Processing

INFORMATION PROCESSING

Difference between data and Information
Data is raw unprocessed information where as information is data that has been to processed to provide a meaningful value.

Information processing is when a machine or processor interacts with the outside world and acts on the input it receives.

ADVANTAGES OF INFORMATION PROCESSING * Tasks can be completed faster * Computers can process large amounts of data and generate error-free results. * Computing storage devices can store enormous amounts of data * Efficiency and productivity can be raised. * Running cost becomes lower in the long term * Automation can be introduced. That is, tasks can be completed with little human intervention. * Overall security can be increased due to less human intervention. * Data and information can be shared with other computers.

DISADVANTAGES OF INFORMATION PROCESSING * It may need a high initial investment in equipment and training. * More money may be needed to employ specialized staff to operate and design the information processing system. * Some jobs may be lost as a result of computerization, which may lower the morale of staff members. * Some staff must be trained or retrained. * Face to face interaction between staff may be reduced.

SETTING UP AN INFORMATION PROCESSING SYSTEM:

Before setting up and information processing system, a business should consider the following questions: * Will computerization really solve the particular problem? * Is it cost effective in the long term? * How large is the amount of data to be handled? * Is high processing speed really important? * Can the present staff manage the system? * How can the loss of jobs be handled properly? * What can be done to help staff adapt to computerization?

EXAMPLES OF INFORMATION PROCESSING * At home, where bills can be paid either by phone or on the Internet. * For research and education through on-line classes where assignments and reports can be submitted electronically. * By all kinds of people who use the Internet to find a wealth of information. * Health care: * Maintain patient records. * Monitor patients’ vital signs. * Perform computer-assisted medical tests. * Research and diagnose medical conditions. * Banking: * Computers are used to keep track of all bank transactions. Customer accounts need to be updated every time a payment transaction is made whether by cheque, card or EFT. Electronic fund transfer (EFT) at the point of sale (EFTPOS) is useful for customers in a shop. * Payroll: * A payroll system uses an information processing system to calculate the wages of each employee, print out pay-sips and record the information for accounting purposes. * Library: * When a new member joins a library that is automated, a membership card is issued which has a barcode printed on it. Every book in the library also has a barcode printed inside it. * When a member takes a book out on loan, the barcode of the book and the barcode of the member’s card are read by a barcode reader. The coded information, along with the date that the book was borrowed, constitutes a transaction. * Control systems: * Traffic lights are triggered by the bumper of the vehicle interacting with the sensor embedded in the road. A traffic light control system would not be very useful or safe if it did not respond adequately to the oncoming vehicles and stop the traffic. * Buildings with air conditioning have sensors which detect the temperature and humidity inside the buildings and turn the heating on or off when needed.

METHODS OF DATA CAPTURE

Data-capture forms

These forms must be designed so that their instructions are clear and concise leaving no doubt as to how to enter the data onto the form.

The responses from the forms are called human-readable since data entry personnel manually enter the responses written on the forms.

One method of avoiding transcription errors is double data entry where the data is entered twice by two different people and the computer will only accept the data if the two versions are identical.

Turnaround document

A turnaround document is a machine-readable document that has some information printed on it by a computer but has more information added to it by a human. It is then fed back into a computer to transfer this newly added information. These documents serve two purposes. They are used to : * Verify the accuracy and completeness of information that has already been entered. * Update information already entered with additional data.

THE SOURCES OF DATA IN SPECIFIED APPLICATION AREAS

Validation
Data validation is the computerised checking of input data for errors before it is processed. There are many different methods of validation. The most appropriate methods to use will depend upon what data is being entered. The most common methods are mentioned below:
Range check
Range check ensures that the data entered is within a certain range. For example, when you enter a number corresponding to a month of the year, the range of acceptable numbers is 1 to 12.
Reasonableness checks
If one is reading a succession of values which ought all to be about the same and one value appears which is widely different then this can be flagged for further checking. For example, if one is inputting a series of electricity meter readings and for one customer the reading is 1000 units (whereas all previous readings were of the order of 100 units) this could be an error.

Consistency checks
Data can change with time. To ensure that it is up to date send a copy of the data to the person to whom it applies and ask them to verify it. For example, every time a credit card company sends an account to a customer the customer is asked to check whether or not the personal details are correct.
Data type checks
This is also known as character or alphanumeric check. When a database is created each field in the database is given a type. Whenever data is entered into a field the database will check that it is of the correct type e.g. alphabetic or numeric. If it is not, then an error message will be displayed and the data will have to be re-entered.
Verification
Data verification is the checking for mistakes such as transcription errors when data is copied from one medium or device to another. Verification checks do not guarantee that the entered data is correct.
Double entry
When entry personnel manually enter the responses on forms they are called human-readable forms. This method of data capture is liable to transcription and other errors when the data is entered into the computer. One method of avoiding transcription errors is double data entry where the data is entered twice by the two different people and he compute will only accept the data if the two versions are identical.

FILE ORGANISATION AND ACCESS:

* What is file organisation * Characteristics of a file * Different methods of file access * Sequential * Index-sequential * Direct-access

File Organisation and access relates to the use of records, fields and files. * A record is a collection of related data items stored in fields and treated as a single entity for processing. * A field contains a single data item, and many fields comprise a record. Each field has a name and one is the key field used to identify the record. * A data file is a collection of records holding the same types of information by about different objects or individuals.

Characteristics of a file:
A files has three important characteristics: 1. Whether it is a permanent or a temporary file. 2. The way in which the records of the file are organized on the secondary storage device. This is called file organization. It may be sequential, indexed or direct, depending on the file’s physical medium. 3. The way in which records are accessed (or located). This is either sequential, direct or a combination of the two.
Different methods of file access

* You can tell the computer how to retrieve records from the file by specifying the access mode. * Sequential * Index-sequential * Direct access or Random

Serial file Organization:

Serial file organization ( also called unordered files) is the simplest type of file organization. The records are arranged one after another, in the order in which they were added. That is they have not been sorted into any particular order.

* Serial files are used mainly for back-up purposes. Recording data in the order in which transactions are made is also useful if you need to restore transactions that have been lost from the master file through problems. * Serial files can be stored on tape, disk or in memory.

Sequential file Organisation:
A sequential file is one in which the records are stored in sorted order on one or more key fields.

* Searching for a record
To search for a particular record, all the preceding records must be read. The main drawback to inserting, deleting or amending records in both serial and sequential files is that the entire file must be read and then the records written to a new file.

* Adding a record
For serial files, you simply add the new record to the end of the file. However the major purpose of sequential files is to preserve the ordering of the file. This means that the record must be inserted into the file in the correct position and not at the end of the file as with serial files. Also you cannot just insert all changes to records in sequential files into the existing file- you must create a new file that contains the inserted records.

* Updating a record
Updating are normally done using magnetic tape in batch mode. All the updates are gathered together into a transaction file, and then applied to the master file together. Updating, therefore, is again accomplished by creating a new file which contains the updated records. Sorting the master file and transaction file records in the same order improves the efficiency of the updating process.

* Deleting a record
With both types of files the only way to delete records is to create a new file which omits the records marked for deletion.

Direct access file organisation:

A direct access file allows access to a particular record in the file using a key. This makes it much easier to find, read, delete, update and insert records. The file is organised like a one-dimensional table on disk where each record is a part of the table. The record number acts like a table index to allow you to find the records.

You can access a record directly or randomly by calculating its location using a mathematical formula and going directly to the record.

Direct access files also support sequential access by allowing the records to be read one after another. The records in a direct access file are not sorted in ascending or descending order, but are stored in random order.

Direct mapping.

Direct mapping uses relative addressing in which the primary key value is relative to the start of the file. That is, a file with space for 1000 records will have relative addresses from 1,2,3 through to 999 and 1000.

Address calculation (hashing)

This is the more common method of direct access file organisation. To retrieve a record from direct access file organisation. To retrieve a record from direct access media, you apply the hash function to the record’s primary key to obtain an address. A block of records is retrieved and its contents are examined to see if the required record is there.