1. Document Reading Methods – The document is in computer readable format. e. g bar code this is input into computer and data is read from it 2. Sensing Methods – Special sensors are used to obtain data which is transmitted to a comp. e. g Traffic lights/automatic weather stations. Different ways of data capture are: 1. KEYBOARD DATA ENTRY – Common way of data capture, Usually copied from a source document so has disadvantages. These Are: Transcription errors – human error as things are copied incorrectly. Time Consuming – Take a long time to input big amounts.
2. Voice Data Entry – User speaks into mic and special software recognizes users voice where it appears on screen to then be edited this can be improved by training to users voice. 3. Scanners and OCR’s – Scanners can print in graphical images and photographs software can then be used to touch up these images. Scanners can also be used to read typed or even hand written documents and OCR can input large volumes of data on pre printed forms such as credit card payments , where customer numbers and the amount paid are printed on the bottom. 4.
Key to Disk Systems – In places where large amounts of data on forms which then have to be keyed in for later processing. An entire comp system consisting of processor, dozens of terminals and a central disk storage maybe dedicated to data entry. When the batch of data has been entered and stored on disk, the sources documents are passed to a second data entry operator who switches his machine to verify mode and keys in the data a second time. The keystrokes are compared with the original and any discrepancies are highlighted so it can be checked for errors. 5. Mouse, Joystick, Light Pen and Touch Screen:
Light Pen – uses light sensors when held over a character or part of a graphic object is detected and object can be moved to modify graphics. Touch Screen – Allows you to make multiple choice answers by touching a screen. 6. MICR Magnetic ink character recognition is used in banks for processing cheques. On a cheque the sort code, customer code are printed in magnetic ink which is processed extremely fast and they read and sort the data and store it on disk. ADVANTAGES: Hard to forge the characters Characters can be read even if cheque is crumpled or dirty *Characters = readable by humans unlike barcodes. 7.
Magnetic Stripe – Credit cards, debit cards, Railway tickets, Phone cards have them the strip encodes up to 220 characters of data. DISADVANTAGES: Easy to copy (prone to fraud) 8. Smart Cards – Similar to magnetic stripes but intead have a chip inside instead of encoded data. Instead of swiping a card they are plugged into a reader. ADVANTAGE: HARD TO COPY 9. OMR – Optical mark recognition can be used to detect marks made in a pre set position on a form e. g multiple choice exams, lottery tickets.
10. Bar Code Reader (Scanner) – 4 Main pieces of info on a bar code are: First 2 digits indicate country product is registered e.g UK = 50Next 5 represent manufacturers code. e. g Cadburys is 00183 Next group of 5 represent product and package size, not price. *Last digit = check digit which id calculated from other digits to ensure barcode is keyed in or read correctly. 11. Graphics Tablet – Flat rectangular slabs which stylus is placed onto. Position of stylus is detected by computer They may come in a wide range of resolutions and types, These are often used by architects in conjuction with a computer aided design package. (CAD) DATA GATHERING AND SAMPLING DATA CAPTURE! Methods of data capture are picked by there advantage in:
SPEED VOLUME ACCURACY COST TYPES OF ERRORS Consider a for being filled in by hand, info will be keyed in and processed these are the possible errors: Customer could make a mistake filling in form Transcription error – person filling in form could write in incorrect data A bored keypunch operator may key in same form twice without realizing. Faulty connection between hardware could mean characters are transmitted incorrectly. VERIFICATION AND VALIDATION VALIDATION CHAECK: Validation is making sure info is inputted sensibly/realistically and not necasarrily correct. USED TO DECREASE DATA ENTRY ERRORS.
Presence check – Certain fields must be present/filled in. Format Check – Code has a set format. e. g postcodes,phone no’s Range Check – Numbers can only be between a certain amount e. g days in a month 0-31 File Lookup Check – If the customers number is entered, his name and address can be displayed to check that it tallies. Check Digit Check – Extra digit is at the end of a code number which has been calculated from the digits of the code e. g bar codes, ISBN. Batch Header Checks – Total no. of records should be calculated by comp and compared with figure on the batch header also includes has and control totals.
Hash Total – Sum of values calculated purely for validation purposes e’g if sizes of all garments ordered on a batch of forms are added together and keyed in, and if the figures don’t match the batch must have an error in it somewhere. Control Total – Same as hash total apart from hash total has no meaning this one does e. g no. of documents in a batch. VERIFICATION – Checks that the data is entered correctly. Verification is the process of entering data twice and comparing the 2nd with the 1st the ensure the data is entered correctly. DETECTING TRANSMISSION ERRORS.
In order to prevent transmitting errors between hardware components a PARITY CHECK is added to each character. In an even parity check the total number of ‘on’ bits in every byte (including the parity number) must be an even number. e. g ASC11 code for letter B is 1000010, the last digit is 0(even) so number of 1’s (on)= 2, an even number, a character code of 11011Duplication of data leading to inconsistent data.
2Operating systems – an OS is software that controls and monitors the running of application programs and it allows users to communicate with the computer. FUNCTIONS OF OS: Memory Management: OS allocated memory to all applications being used, It manages the swapping of the contents of memory out to disk known as virtual memory because it makes the comp appear to have more memory than it actually does. Resource allocation and scheduling: OS is responsible for allocating processing time, memory and input output resources. Backing Store Management: OS controls data transfer of data from secondary storage to memory and back again.
It maintains a directory of the disk so that files and free space can be allocated quickly. Interrupt Handling: OS detects the many different interrupts such as user pressing enter on keyboard, a printer sending a msg that its out of paper. Allowing the user to communicate with the computer: the user gives the instructions to the comp to start a program, copy a file, send a msg, this is recognized by the OS through the interface e. g GUI, mouse, pointer. EXAMPLES OF OS DOS – Disk operating systems. This is a command driven interface. The user types in commands in the exact correct syntax to perform operations.
Windows 95,98,Me – These have GUI using WIMP environment (WIMP – Windows Icon Menu Pointer) Linux RiscOS MacOS Software Categories: 1. Systems Software 2. Applications Software 3. General Purpose Software (generic) 1. Systems Software Software is a general term for all programs that run on a computer. There are 3 Categories: OS Utility program – these perform tasks e. g search for lost files, sort files, copy disks for backup Communications – control flow of data to and from remote locations 2. Applications Software – Written to perform particular tasks: PAYROLL STOCK CONTROL.
Application software may be written for a company(bespoke software) purchased off the shelf. Generic Software: all common applications software: Word Processors Databases Spreadsheets Usually sold as a package with CD, Manual. INTEGRATED PACKAGES AND SOFTWARE SUITES Integrated Packages: These are a combination between five applications packages Word processor, Databases, Spreadsheets, Presentation Graphics and Communications software e. g MS Works. These are less sophisticated than an individual package but are relatively cheaper.
Software Suites: These are software products packaged together at a much lower price e.g MS office provides word, excel, access, powerpoint. These are applications which are compatible with no difficulties with importing data from one package to another. They have same Common user interface (look, feel, shortcut keys) So are easier to use. BESPOKE/OFF THE SHELF SOFTWARE! Advantages of buying off the shelf: Generally less expensive Possible to speak to others to evaluate the package *Software can be brought/Installed straight away *Software is tested and less likely to contain bugs like just written software *Software is usually well documented *Training maybe available in common software packages.
Advantages of tailor made/bespoke software: *Software is designed exactly to user requirements *Software can be written to run on specific hardware *Software can be integrated with existing software *There may not be a package suitable on sale SOFTWARE PRODUCTIVITY TOOLS These are generally application packages that are used to perform operations that are an integral part of day to day business operations. Most common ones are word processing, Spreadsheets, Databases, Management systems and electronic e-mail. These 4 applications now form part of the basis of both integrated packages and software suites.
WORD PROCESSING: Word processors are used to edit, format, store and print documents. Important features include: 1. Spell/grammar check 2. Automatic creation of index/table of contents 3. Mail merge – a document and a list of names and address can be merged to produce personalized letters. 4. Import files – tables, photos, graphics, video, sound 5. Creation of Templates – pre-set text styles, margins, Formatting, Letter headings 7. WYSIWYG ‘What you see is what you get’ displays exactly on screen what you will get when text is printed. SPREADSHEETS These create worksheets representing data in columns/rows form.
Used for numerical data e. g budgets, cashflow forecast, profit/loss statements, experimental results. Important features include: Create Graphs and chart CAPABILITIES OF SOFTWARE (OLE) Object Linking and Embedding! Using OLE, it is possible to share information between programs e. g a report is written in word which requires the use of a spreadsheet/chart created in excel, the spreadsheet can be either linked or embedded in the document. Main difference between embedding and linking an object is how the data is stored and how it is updated after palcing the destination file.
USE LINKED OBJECT IF: You want the info to reflect any changes to the original data or File size is a consideration With a linked object the original data remains stored in the source file. The destination file displays a representation of the linked info but stores only the location of the original data. The linked data is uploaded automatically if you change the original data in the source file . With an embedded object it becomes part of the destination file. Because an embedded object has no links to the source file, the object is not updated if you change the original data. Macros.
Macros are a stored sequence of instructions or program to carry out a task automatically. It is useful for actions which are required frequently. They can be executed by icons on menus or hot keys. Printer Driver A printer driver is software which stores the set up configuration for a particular model of printer. It translates the info (highlighting/fonts/formatting) into a form the printer can understand. It avoids the user from having to enter control codes into the printer directly. Portability of Data Portability is the ability to run the same program/data on different types of computer.
It can refer to the ability to transfer a file from one computer to another. It is important to be able to transfer data between applications and computers or even operating systems. For Example: Writing a report in word and want to insert an excel spreadsheet. Using a DTP package and want to be able to import some graphics from a drawing package. *Researching on the internet and want to be able to download articles. *Want to e-mail someone using a unix machine. Files (binary, text or graphical) can be downloaded from the net using FTP (file transfer protocol) software that can copy files between different types of computer.
Types of file formats that help with the portability of data: CSV – comma separated values, used for transferring data from, for example, a database into a spreadsheet where the data is tabulated, e. g name and address each field. Bit Map -A graphics file, it is an image which is digitized in pixels which represent a number containing the colour or intensity or shade. It is stored as a fixed number of bits. PROBLEMS OF PORTABILITY! A document created on WP package commonly cannot br read by another WP package (Word to WordPerfect).
Different formatting codes are used by different packages. However most WP allow documents to be stored in ‘text only’ format. This strips all formatting information and any graphics, leaving only text. *A document created on one computer using a particular WP appears differently on the screen of another running the same WP. Some WP lay out a document based on the printer being used. If the document is transferred to another computer and a different printer, the document may appear with a completely different layout, with line breaks and page breaks appearing at different places.
*Another reason why a document may look different on another computer is that the fonts are not the same. A different font will be used and this will change the layout. UPGRADABILITY Upgrades to software are common about every 2 yrs. Upgrades can do the following: *Documents or applications produced by the upgrade are not ‘downwardly compatible’ i. e documents written in Version 6 can usually be read in version 7 but ones written in 7 cant be read in version 6! *New version will probably contain new features so that data or formatting may be lost if it is converted to the earlier version.
*The upgrade software normally needs more memory and disk space etc so your hardware may need upgrading. *However new software versions does mean improvements in case of use, functionality and speed. RELIABILITY If a systems/program is produced it must be reliable i. e it must work without any errors.
Testing strategy should be prepared after the design of the system with prepared data to use. The testing should cover errenous/extreme data. The data must also be checked that it follows the system correctly. As software becomes more complex it becomes more difficult to test. With GUI interfaces and online systems, Full effective tesing is impossible. It is impossible to recreate the conditions on under which a program crashed. THESE DIFFICULTIES ARISE BECAUSE: *There is no single, well defined flow of events at the user interface.
*It is often impossible to restore a database to the condition it was in before a bug was detected. *Rapid, Iterative and continuous development techniques mean that software continues to develop and new, weekly versions of software are released by programmes. Testing simply cannot keep pace with the rapid changes. *Users often use new software in ways which were not anticipated by software engineers who wrote the system. When the system finally crashes it is impossible to retrace the sequence of events which caused the crash. Performance testing is difficult to step up.
An online, multi user system that works well when tested with 1000 records and 2 users may not work when a million records and hundreds of users are simultaneously accessing the database. CRITERIA FOR SELECTING A SOFTWARE PACKAGE!!! Most important factor is how well it meets your needs others are: Compatability with existing hardware. Will software run on existing equipment? Compatability with existing software. Can files form other packages be imported/exported to an from new and other packages. Quality of documentation. Ease of learning. How good is online help. Are tutorials available? Ease of use. Is it user friendly?