Below the GO's screen, you'll find only two buttons--one for power and the other for removing the device from its mount--and an SD (Secure Digital) slot for loading the OS and maps. All menu and screen selection functions are activated via the touch screen, which is responsive. The sound quality of the built-in speaker is also impressive. The GO comes with 32MB of internal memory and a 256MB SD card, which includes TomTom's navigation software and maps of the major U.S. roadways. It's also packaged with a CD that contains comprehensive street-level maps and points of interest (POI) for all 50 states. You can upload that data by state or region to the SD card via a mini-USB port on the device. If you want to carry extra maps on multiple SD cards, you'll have to load the application software as well. TomTom also includes adapters for both AC power and cigarette-lighter connections as part of the package.
Navigation options include route creation to and from addresses, POI, or your current position, as well as recent destinations. The directions can be displayed as text with mileage or estimated timer markers for each leg or as a detailed map with your choice of 2D or 3D graphics, and you can easily calculate alternate routes if you veer off course or if you wish to avoid roadblocks. The TomTom GO also conveniently features ASN (Assisted Satellite Navigation) technology, which is similar to Garmin's Dead Reckoning and utilizes special sensors to calculate and hold your position when traveling through tunnels.
Zooming in or out on the map is as easy as touching the plus or minus icon on the screen, and you can set the level of detail displayed on the map to avoid crowding of POI icons and street names. You can even set the touch screen for left-handed use, change map colors, and invert the screen if the unit is mounted at an awkward angle. The GO also includes an internal clock, a battery meter, and the usual satellite status and screens. The TomTom GO performed superbly in our tests. We established a 3D fix within 40 seconds of power-up and never lost satellite reception throughout our tour of Manhattan, Brooklyn, and Long Island. We were pleased to see that the GO kept a virtual lock on our location while traveling through the Midtown Tunnel and picked up our actual position the moment we emerged from the tunnel. Voice-guided directions were loud, clear, and on the money, and the 12-channel receiver was extremely accurate with regard to our position on the map. The rechargeable lithium-ion battery, rated for 5 hours of constant use, gave us just that, with about 10 minutes to spare.