The four major subsystems of the Cyberguide unit are positioning, communications, information, and historian. In most of the previous versions of Cyberguide, mapping would have been considered a subsystem, yet in this design of Cyberguide, mapping is simply the graphical display of information.

Here is a Data Flow Diagram depicting the flow of functional data throughout the system.

Evidence from previous quarters proved that present Newton technology did not contain the processing power to do the tasks that were inherent to Cyberguide. Therefore, the MessagePad2000's release has been long awaited. The MessagePad2000 uses the new StrongARM processor. As one source at Apple put it: "you now have a mid-range Pentium system that you can hold in your hand." This processor has be hypothesized and feasiblity tested to assure that it can do view rendering (the most CPU intensive process of the system). It can be assumed that this computer uses one processor. This trait is inherent for pen based units. Therefore the subsystem task have to be allocated to the processor via a priority of event task.

The order of the event priorities are as follows:

1. View Rendering - This is the most intensive of all functions. It must be completed quickly and effectively so that the map is constantly updating the position of the user.
2. Position Updating - After a view is rendered, the next position of the user is requested. When a certain distance has been moved from the previous position, a new position is broadcasted. If Cyberguide To Cyberguide communication is on, this information will be broadcast to the View on a intermittent basis.
3. Point of Interest Adding/Editing/Observing - When points of interest are being added or edited, the previous two tasks complete their cycle, and are then paused so that the information is allowed to be entered. When observing POIs, the information is loaded using a substantially lower amount of the processor usage than any of the other events listed above.
4. E-mail and WWW - These functions present a very interesting problem. The network communication of these functions will interfere heavily with Cyberguide To Cyberguide and any other functionality over the comm line. Therefore when these items are on-line, the rest of Cyberguide simply shuts down, and wait until the work on these items is complete.
5. Historian - The Historian performs very non-essential tasks. It will basically do its task when the CPU is not under stress from any of the items above.

As of now the hardware requirements are a PDA with either the StrongARM or an equivalent processing power, a digital camera that is preferably CPU controlled, and a Global Positioning System.

The connectivity topology includes the Newton MessagePad2000, a camera, and a GPS unit. The configuration of this topology could be as in this figure below:

The digital camera uses either a serial port or a PCMCIA card slot.
The GPS uses either a serial port or a PCMCIA card slot.
The communication device (modem, wireless lan, etc.) uses a PCMCIA card slot.
It is preferable to have more flash memory which will also uses a PCMCIA card slot.

• Minimum Configuration - 1 serial port, 1 PCMCIA card slot (no camera, no flash memory)
• Necessary Configuration - 1 serial port, 2 PCMCIA card slots (no flash memory)
• Preferable Configuration - 2 serial ports, 3 PCMCIA card slots (option of where to put the camera or GPS)

Database Systems
In order to achieve platform independence in this system design we will not assume that any particular Database Management System will be used.

Main Application Database:
The main application database will consist of two types of objects, Polylines and Points Of Interest (defined below).

Polyline Object

Type	Field Name	Description
Rectangle	BoundingRectangle	Bounding rectangle of the polyline in world coordinates.
String	Name	Identifying string data (e.g. as the name of a street.)
Number or String	Classification	Classification information (e.g. the classification of the polyline Water, Boundary, Secondary Road)
Point List	Vertices	List of vertices ( in world coordinates) that make up the polyline
Number	NumberOfVertices	The number of vertices that make up the polyline.

Point Of Interest Object

Type	Field Name	Description
String	Title	The title of the point of interest. (e.g. The Student Center)
String	Info	General information about the point of interest.
Point	Location	Location of point of interest in world coordinates.
String	ImageFileName	The name of an image associated with the point of interest.
String	ImageCaption	A caption for the associated image.
Number	RadiusOfInfluence	The radius for a sphere of influence for the point of interest.

Main Application Database

Camera module

Position module

Communication module

Initialization of the system

Termination of the system

Failure of the system

At the present time, this system is a real-time information application that has on-line capabilities. The top priority of this system is to provide information concerning the position and surroundings of the user. Therefore, the real-time aspect will always be more important than any other function.