Calculations of speed, distance and direction, the dynamic relationship between representation and reality, between text, drawing and thing are too complex for a normal couples capabilities. Quite frankly, we've developed landscapes beyond our own comprehension. We've made our own planet an alien environment.

No wonder we've had to invent tools to help us. The market is now full of Satellite Navigation products that can guide us through interchanges, junctions, on ramps and off ramps. Sat Nav is made possible by the orbiting infrastructure of the Global Positioning System. Developed by the U.S. military, it's made up of twenty-one satellites, orbiting 20,200 km above the earth. Full operational capacity was declared in June 1995. Civilian access to GPS technology was granted by the US Government in May 2000, when 'selective availability' - intentional errors that fuzzed the accuracy of positioning was switched off. Reading the small print on consumer navigation products reminds you that 'GPS is operated and controlled under the sole responsibility of the Government of the United States of America, who are responsible for its availability and accuracy'.

I've had TomTom Mobile 5 on my Nokia 7710 smart phone for a while now. It connects via Bluetooth to a small GPS unit. Currently, its maps only cover the UK. I'd been trying to shoehorn hooky downloaded versions of maps of France onto my 7710 in an attempt to save my relationship. But time, and TomToms encryption, sealed my desperate fate.

The TomTom Go 700 - an all-in-one unit: gps/screen/software/hard disk - provides a map that stretches across Europe: from Ireland to Poland. It makes one imagine a life where one might need that kind of facility: road haulage? world domination?

This is a modern kind of invention. Made by intelligent licensing of different things rather than isolated creativity. In TomToms case that includes data from Ordence Survey, GPS from the US Government, connectivity to other devices via Bluetooth, a modified Linux OS, an ARM processor, and that it can be ported to run on Nokia hardware with Symbian OS. It pulls pieces of function together then binds them with the software equivalent of gaffer tape. It creates a new facility out of a new arrangement of existing technologies. Design by patching, splicing, and opening up ports of communication between different systems. As technology becomes more sophisticated, it becomes more specialised. High technology products require these specialised elements in the same way that industrial production requires raw materials. Products inevitably become patchworks of licences, brought together by a functional vision, inside a snazzy box.

TomToms proprietary bit is the navigation and interface - what it does with the map data, and the bit you to interact with. And this is really simple. Type in a destination, and it calculates a route. Then, as you drive (or walk, or cycle) it displays a map with an arrow showing your position. Before a junction it tells you to what action to take. If you take a wrong turn, it updates the route. That's it. There are ways of making itineries, of avoiding roads or places, of updating traffic and weather information too.

Simple right? But incredible in the way it changes the nature of travelling. It means you can use landscape differently. You'll never need to worry about how or how long it will take to get home. You can head off and explore guided by intuition, then hit the 'home' button that, like Theseus' ball of string guides you back to your start point. It lets you travel, then unravel.

The potential of TomToms technology is immense. As well as guiding you, it also alerts you to nearby POIs - Points Of Interest. The preloaded set mainly consist of the nearest McDonalds and petrol stations. But you can also make your own, and publish or download sets from GPS hobby-ist websites: prehistoric monuments, roman sites, castles abattoirs, are current selections. Spiralling from the generic to specific, they start to suggest that device like this might change from assisting your journey to why you travel. The POIs make links between geographical place and information database. It's a portal that can allow information to continuously flow across the landscape as you move.

It means landscape and information can be linked. Which in turn makes all kinds of things possible: novels could be played out in space across a Yorkshire moor, Wiki travel guides could allow access to comments and suggestions from internet users. It could unleash torrents of amateur psychogeography. It could mean every step was accompanied by Michael Palin, David Attenborough, Julian Cope, Iain Sinclair, AND Peter Akroyd.

Maps are beautiful things. But frustratingly arcane to most of us. TomToms brilliance is its reinvention of a map as fluid, active and communicative data. It might even make driving around Paris a pleasant experience.