Human-computer interface

Human-computer interface

1. Interfaces

   • Command line interface
     • User types instructions using special set of words/symbols
     • Used in the early stages of computing
       • only suitable for skilled ICT users as instructions must be known
     • quick exercution
   • Menu-driven interface
     • Menu of options displayed for the user to choose from
     • simple and user-friendly as the options do not have to be remembered
     • simple
   • Graphical user interface
     • Small pictures (icons) used to represent availble options
       • Microsoft windows
     • low level ICT
   • Voice interface
     • Microphone used to speak commands into the computer
       • analyses voice patterns and complies to instructions
     • disablities
   • Special devices
     • for the disabled/children
       • concept keyboards/touch sensitive screens/puff-suck switches

2. Other systems

   • on-screen help
     • context related help
     • old verions had annoying pop up context sensitive hep which was often turned off
   • EPOS interface
     • Data input through barcode reader
       • data pops up on screen and reciept is printed
   • Biometric
     • use physical factors such as fingerprints
       • high level of security but very expensive
         • analyses features to see if they match your features
   • Computer software
     • program is a set of instructions thta tells the computer what to do
       • systems software = programs that help the computer system work
         • Applications software = programs that perform special tasks/used for general purpose task (word processing)

3. Operating Systems

   • Loads and runs programs
     • maximises use of memory (RAM)
       • handles inputs and outputs
         • deals with interuptions
           • maintains system security
   • single-program systems
     • runs one program at a time, slow
     • Batch-processing systems
       • program with data needed = job
         • jobs are queued and are all processed together
           • used when there is no urgency for the job to be done
             • can be done at off-peak times/no human intervention needed
       • Multi-programming systems
         • Computer holds more than one program in its memory and gives each one a smal amount o processing in turn that makes it look like they are being processed all together
           • more programs are processed in less time
         • Multi-access
           • Mainframe computer has workstations spread out along differnt floors and levels
           • workstations connect interactively, each program is processed quickly and given the right resources
           • Distributed systems
             • processes and resources shared among connected computers
             • real time systems
               • Data processed as soon as inputted
                 • sensors used to give data which is immediately processed and will take action if needed
                   • Reacts fast to situations such as fires or flight simulators
               • Real-time transaction processing
                 • item sold or booking made the data is processed immediately to take of stock record or add to database
                 • Parallel-processing systems
                   • large mainframes have more than one processor to speed up process time as large amounts of data come in at all times
                   • Interactive systems
                     • ATM requires the user to tell the computer what to do
                     • Systems security
                       • single user systems = protecting files of data
                         • multi user systems = checks every username and password
                           • keeps log of computer usage
                             • backs up data
                           • time/date of last time files were changed
                             • sets files to read only
                               • deleted files are put in recycling bin
                                 • can recover accidentaly deleted data