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Human Computer Interface

It is important to understand that the computer is a machine to serve us as humans.  It is a means to an end, not the end itself.  Some people are frightened by computers because of the mystique that can sometime surround these machines, and they credit the machines with a diabolical and spiteful intelligence that is out to get them at every opportunity.

 Some of the mystery that surrounds the computer stems from the early mainframe machines that needed skilled and specialised staff to run them.

 The important thing to remember is that the computer is an adding machine.  It can only add (not subtract, nor multiply, nor divide) two binary numbers.  It does this very fast.  Every function a computer does is entirely because a programmer has written out a set of instructions that tells the computer exactly what to do.

 Think about writing a set of instructions to do (an algorithm) when you get out of bed in the morning:

1. Get out of bed;
2. Go to the bathroom;
3. Have breakfast;
4. Get on the bus
5. Get to college.

You have to tell a computer everything, like writing down every single muscle movement required to remove the duvet, and lifting your body from your bed.  All the spatial coordinates need to be given to the computer…

You can see that writing sophisticated programs requires mammoth amounts of work.  The good news is that the hard work has been done for you so that you can easily get a computer to work for you.

The most common operating system in the early days of PC’s was DOS invented by the Microsoft company in the early eighties.  It tells the computer how to read, write, and format disks, and manages the peripherals.  It is a command-driven interface, which means that the user has to know the commands in a particular syntax for an given operation.  Those experienced in DOS can carry out commands faster than with a mouse and pointer.  However not many people are confident with DOS.  Also DOS can only allow one application to be open at any one time.  The picture below shows the idea:

A superior system was produced by the Apple Computer Corporation, which was known as the Graphical User Interface (GUI).  This involved the use of a mouse with pull-down menus.  This interface is also referred to as WIMP (Windows, Icons, Mouse, Pointer).  It also gave us the term user friendly.  Unfortunately, Apple were not so shrewd as Microsoft, and would not license their product for use with PC’s other than theirs.  Therefore the IBM with DOS became the normal standard, while the owner of Microsoft, William Gates, became obscenely rich.

Question 11  State the difference between a command line interface and a graphical user interface.  Give one advantage of each.

ANSWER

 We can make our own user interfaces using text boxes and command buttons.  Here is one for a database.

 Good interfaces must have:

ANSWER

Interfaces with some children’s software are particularly bad.

Let’s look at a few interfaces:

 It’s bad because it’s too crowded and possibly confusing to a user.

 This one is bad too:

It is bad because:

• It has a timer on the menu bar.  The timer should really be at the bottom, in a separate window;

• There are no titles to the frames, so what each frame refers to is not certain.

This interface is good:

• It is not cluttered.
• Each function has a clearly marked button.
• Each button has an icon;
• All the columns have headings.  Although not all the headings may be obvious at first sight, there is a help button so that a new user can go to get help on any feature they don’t understand.

Question 13. Look at this interface:

  Discuss whether you think it’s good or bad. 

Answer                                                               

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