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Computer Files

Updated : April 4th, 2009
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Naming Files

Programs and data are stored on a computer in the form of files. Files are named collection of stored data. Each file must be given a name to identify it. A complete file name carries two parts. The first part is called the file name and the second part is called the extension. They are both separated by a period or full stop.

A file may be defined as a grouping of related records. A record is a collection of data items that relate to a single unit. Each record is made up of fields and each field consists of a number of characters. A character is the smallest element in a file and may be a letter of the alphabet, a digit or a special character such as anyone of the following ( $, !, #, %, ^, &, *, (, ), +, |, <, / ) ect.

Older PCs running the Disk Operating System required that the file name be no more than eight characters and the extension be no more than three characters for example ( myfile.txt ). In Windows 95 and later Windows Operating Systems the file name and extensions can be much longer, up to 255 characters long. This facility permits the user to use more descriptive names.

The following characters are disallowed in a file name :

\ / ; * " ? < >

Common File Extensions

We can have an idea of what type of data is contained in a file by looking at the file extension in very much the same way you can tell to which family a person belongs by knowing his surname.

File Extension	Explanation
BAT	A Batch file contains a series of DOS commands
BAS	Basic program source code
C	C program source code
COM	A command file - one that is executable in DOS
DOC	A document file in Microsoft Word
DOCX	A document file in Microsoft Word 2007
EXE	Executable command file
PAS	Pascal program source code
SYS	A computer system file. Many control hardware devices
TXT	A simple Text file
BMP	A Bitmapped graphics file

Directories and Folders

Files should always be placed in folders in order to manage them effectively. Placing files in folders makes it easier to find a file you are looking for.

The Windows Explorer

The Explorer is a Windows program that enables you to manage your files and folders. The file manager allows you to copy, move, delete, and rename files.

Starting Windows Explorer

• Click on the Start Button
• Point to Programs
• Click on Windows Explorer

Master Files, Transaction Files and Reference Files

A Master File is of a fairly permanent nature. These files need to be updated regularly to show the current position.

A Transaction File is made up of various transactions created from source documents and is used to update the masterfile.

A Reference File has a reasonable amount of permanency like a customer name and address, reference file or a product reference file holding product code, product name and price.

Registered Students may email The Tutor at tutordam@yahoo.com with your questions and or comments.

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