ACSC 155 System Analysis and Design 5. Input/Output Design

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ACSC 155 System Analysis and Design5.
Input/Output Design
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• Input/Output Design
• User Interfaces

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Data Entry Methods and Devices

• Keyboard
• (QWERTY)
• Ergonomic
• Touch-sensitive
• Musical
• Mouse

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Keyless Data Entry

• OCR (optical character reader)
• OMR (optical mark reader)
• MICR (magnetic ink character reader)
• Barcode readers
• Pen Input
• Scanners
• Graphics Tablet
• Microphones

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Output Methods and Devices

• Screens
• Printers
• Speakers

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Graphical User Interfaces (GUIs)

• A method of user communication with an operating
  system. Basically, to give commands.
• By selecting icons, buttons, bars or boxes.
• Quick and easy to learn.
• Promote standardisation of application program
  interfaces.
• Reduce errors.

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System User Issues for Input Design

• Volume of input should be minimised
• Enter only variable data, do not enter constant
  data
• Do not input data that can be calculated or
  stored in computer programs
• Use codes for appropriate attributes
• Source documents should be easy for system users
  to complete
• Include instructions for completing the form
• Minimise the amount of handwriting

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• Design documents so that they can be easily and
  quickly entered into the system
• Data to be entered should be sequenced
• Portions of the form that are not to be input are
  placed in or about the lower right portion of the
  source document

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System User Issues for Output Design

• Computer outputs should be simple to read and
  interpret
• The timing of computer outputs is important
• The distribution of computer outputs must be
  sufficient to assist all relevant system users
• The computer outputs must be acceptable to the
  system users who will receive them

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Internal Controls for Inputs and Outputs

• The number of inputs should be monitored
• Care must also be taken to ensure that the data
  is valid
• The timing and volume of each output must be
  precisely specified
• The distribution of all outputs must be specified
• Access controls are used to control accessibility
  of video (on-line) outputs
• Control totals should be incorporated into all
  reports

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• ISAM Indexed sequential access method
• For storing data records on a physical storage
  device in sequential order for sequential
  processing
• Allows direct access to the particular record
• Batch mode versus On-line processing
• Methods of interacting with a system
• - command language
• - menu
• - form
• - object
• - natural language

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Fourth-generation language

• Extremely sophisticated languages
• Little or no professional programming skills
• Categories (7)
• Query languages
• Report generators
• Graphics languages
• Application generators
• Very high-level programming languages
• Application software packages
• Microcomputer tools

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Testing and Debugging

• Testing
• Black box testing
• White box testing
• Alpha and Beta testing
• Selection of test data

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• Debugging (Errors or bugs)
• Translator diagnostics
• Cross-referencing, Traces, Variable dumps
• Dry runs
• Splitting the program
• Test strategies

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Installation - Integration

• Parallel running
• Pilot running
• Big bang, or direct change
• Phasing