Interface Evaluation

• Command line: In general, the command line interface is unsuitable for all but expert-level applications due to the command vocabulary necessary to use interfaces of this particular type.
• Form-based: Given that interaction with the system can be considered a series of financial transactions, a forms interface is a possible candidate for an interface for the system.
• Menu-based: Current ATM systems utilize a menu-based interface. Since such systems act as a model for the TURBOMail system, this is also an appropriate interface possibility for this system as well.
• Natural language: Assuming that the technological capability for such an interface existed, the NL interface fails to properly restrict the user's input domain, and would therefore be the probable cause of considerable error while the user determined what sorts of actions were valid in the system.
• Question/answer: By constraining the user input as much as possible, it is possible to create a simple system to use. Since most of the tasks proposed to be accomplished by TURBOMail are of a simple nature, the data necessary for their execution could be obtained by question-and-answer dialogues with the user. This is a candidate for an interaction style for the system.
• WIMP: Although the functionality of a WIMP interface is certainly sufficient to implement the functions of the TURBOMail system, WIMP is a complex, intricate interaction style with a relatively high learning curve. The expressive power of this particular interaction style is much greater than necessary for this system, so this should not be considered as a possible candidate for the interface type for the system.

A form-based interface will require a data entry method for the various fields, which suggests a keyboard (or other button array) or a digitizing tablet or light pen. Also required is a means by which to move from field to field in the form, which suggests a pointer device such as a joystick, mouse, trackball, or touchscreen, or a set of positioning keys or buttons.

A menu-based interface will require some sort of pointing mechanism to move through the menu choices (joystick, mouse, etc.), or a series of buttons which map logically to menu choices (a one-to-one mapping in a button array, or semantically-appropriate mappings, as in a keyboard with accelerators).

A Question/answer interface will require a data entry method for responding to questions (keyboard, buttons, light pen), unless all of the answers are explicitly enumerated for each question, in which case a pointing device will be sufficient.