In addition to each data element including information for identifying the location of the relevant map segment such that data elements can be transmitted as independent elements, the content of each data element is preferably organised into a plurality of independent components.

"Independent" in this context does not mean that their information is not related to each other, but rather that the transmission of each component and its interpretation by the receiving device is not dependent on other components.

This embodiment of the invention is preferably implemented by including data component delimiters within the transmitted data stream.

If a communication failure occurs, it is then possible to determine which components were successfully received and to process the successfully received components at the mobile device rather than having to treat the whole data element as failed.

The data element components are preferably ordered within a data element such that the more significant components are at the beginning of the data element.

In a further embodiment of the present invention, there is provided a solution combining static provision of geographic information (such as on a CD-ROM or DVD-ROM) with dynamic updates to the static information.

Updates since the latest distribution of a static database of geographic information are transmitted as described above and the receiving device superimposes the received update information on the map grid.

This involves transmission of significantly less data than if the complete map data is transmitted, while still achieving the currency of local data which is achievable by fully dynamic solutions.

The broadcasting of geographic data according to the invention is preferably a digital wireless broadcast which can be received by any receiver device within the vicinity of a transmitter, but it may also be an interactive broadcast where the receiving devices can influence the content or other characteristics of the broadcast, or a transmission to specific user groups.

Improved methods and operating systems for use with a multi-mode microprocessor enable efficient operation in a multi-mode environment.

Preferred embodiments for use with microprocessors which were not designed to switch from each mode to another mode enable multi-tasking of a mixture of programs written for different modes using the mode switching methods of the present invention.

Frequently used portions of the operating system are stored in memory at locations which can be commonly addressed in all modes.

Means for handling device drivers and interrupts in all modes are also provided.

Preferred embodiments for use with computer systems using microprocessors such as the Intel 80286 include means for storing the operating system routines to maximize performance of the system in real mode.

Auxiliary protection hardware and I/O masking hardware are also provided in alternate preferred embodiments to enhance protection during real mode operation of such systems.

Means for handling interurpts in a mode switching environment and alternate embodiments to eliminate problems caused by hooking programs in a multi-tasking environment are also provided.

This invention relates to improved methods executing computer programs in a multi-mode microprocessor and improved operating systems for use with such microprocessors.

Newly designed microprocessors may include enlarged memory addressing facilities and revised architecture which result in enhanced capabilities.

When such microprocessors are used in new computer systems, they often produce computers which are functionally superior to their predecessors due to these enhanced capabilities.

Despite any functional advantages a new computer may have over its predecessors, a computer employing an improved microprocessor may not be a commercial success.

Computer programs, sometimes referred to as "software," are microprocessor specific.

Therefore, when a computer employing a new microprocessor is introduced into the marketplace, there is generally little or no software which can run on it.

Existing software, written for previous microprocessors, is incompatible with the new computer.

As a result, sales of such new computers will often be sluggish until consumers see that adequate software is available for the computer.

Additionally, consumers with libraries of software for existing computers may be reluctant to purchase new computers which would require them to invest in all new software.

This problem is often compounded by the fact that software writers and publishers are reluctant to produce software for a new microprocessor until sales of computers incorporating the microprocessor are sufficient to create a relatively large group of potential purchasers of the software.

This "wait and see" attitude on the part of both consumers and software writers can jeopardize the success of a new microprocessor and computers using the microprocessor.

Designers of new microprocessors sometimes attempt to solve this problem by designing a new microprocessor such that it will operate in two modes.

In a first mode, the microprocessor will emulate a prior microprocessor and run existing programs written for the prior microprocessor.

In a second mode, the microprocessor will make full use of its enhanced capabilities.