Digital System

Advantage

1. Have made possible many scientific, industrial, and commercial advances that would have been unattainable otherwise.

2. Less expensive

3. More reliable

4. Easy to manipulate

5. Flexibility and Compatibility

6. Information storage can be easier in digital computer systems than in analog ones. New features can often be added to a digital system more easily too.

Disadvantage

1. Use more energy than analog circuits to accomplish the same tasks, thus producing more heat as well.

2. Digital circuits are often fragile, in that if a single piece of digital data is lost or misinterpreted the meaning of large blocks of related data can completely change.

3. Digital computer manipulates discrete elements of information by means of a binary code.

4. Quantization error during analog signal sampling.

Graphical System

Advantage

1. Symbol recognized faster than text: Researchers have found that symbols can be recognized faster and more accurately than text and that the graphical attributes of icons such as shape and color are very useful for quickly classifying object, elements or text by some common property. These icons allow speedy recognition of the type of message being presented.

2. Faster learning: It has been found that a graphical, pictorial representation aids learning and symbols can also be easily learned.

3. Faster use and problem solving: Visual or spatial representation of information has been found to be easier to retain and manipulate and leads to faster and more successful problem solving. Symbols have also been found to be effective in conveying simple instruction.

4. Easier remembering: Because of greater simplicity, it is easier for casual user to retain operational concepts.

5. More natural: Graphical representations of objects are thought to be more natural and closer to innate human capabilities. It has also been suggested that human mind has a powerful image memory.

6. Foster more concrete thinking: Displayed objects are directly in the high-level task domain or directly usable in their presented form. There is no need mentally to decompose tasks into multiple commands with complex syntactic form. The need for abstract thinking is therefore minimized.

7. Fewer errors: More concrete thinking affords fewer opportunities for errors. Error messages are less frequently needed.

8. Increased feeling of control: The user initiates actions and feels in control. This increases user confidence and hastens system mastery.

9. Less anxiety concerning use: Hesitant or new users feel less anxiety when using the system.

10. More attractive: Direct-manipulation system is more entertaining, cleverer and more appealing.

11. May consume less space: Icons may take up less space than the equivalent in words.

12. Replaces national languages: Language-based systems are seldom universally applicable. Icon possesses much more universally than text and much more easily comprehended worldwide.

13. Easily augmented with text displays: Where graphical design limitations exist, direct- manipulation system can easily be augmented with text displays.

14. Low typing requirements: Pointing and selection controls such as the mouse or trackball eliminate the need for typing skills.

15. Smooth transition from command language system: Moving form a command language to a direct-manipulation system has been found to be easy.

Disadvantage

1. Greater design complexity: Controls and basics alternatives must be chosen from a pile of choices numbering in excess of 50. The design potential may not necessarily result in better design, unless the choices are thoughtfully selected and consistently and simply applied. With graphics, the skill of the designer is increasingly challenged.

2. Learning still necessary: The meaning of many words and icons may not be known. A severe learning and remembering requirement is imposed on many users, and it takes a while to get up to speed. System providers estimate that becoming accustomed to a graphical interface should require about eight hours of training. Other experts say the learning time is closer to 20 or 30 hours.

3. Lack of experimentally-derived design guidelines: The graphical interface is still burdened today by a lack of widely available experimentally-derived design guidelines. Too many variables that must be controlled make meaningful cause and effect relationships very difficult to uncover.

4. Inconsistencies in technology and terminology: The inconsistencies occur because of copyright and legal implication, product differentiation consideration, and our expanding knowledge about the interface.

5. Working domain is the present: While direct-manipulation system provides context, they also require the user to work in the present.