Limit on installing maps on a Colorado?

[gpspenguin]

Absolute newb question here. Im very new to GPS so trying to work it all out.
Ive recently purchased a Garmin Colorado and am trying to load a number of maps onto it. Although its got plenty of memory (4GB SD HC card)
I dont seem to be able to load all the maps I have :-

City Navigator
Tracks4Australia
Topo Plus (Johnny Appleseed topographic map - I realised afterwards I could have used shonky maps instead?)

Including the bundled base map I seem to be only able to install 3 maps.
When I download a 4th map it just overwrites an existing map with no warning.
Is there a 3 map limit on the Colorado? Just wondering what Im missing here.
Ive done alot of searching and I cant find much info in the manuals or on the web about this.

Also, is it possible to view all of the above 3 maps simultaneously on a Colorado?

Thx in advance for any help you can give me.

The penguin

[Dooghan]

I bet it suffers from the 2.1Gb or 2100 map limit. I think just by putting all of Topo Plus on by itself would go over the 2100 map limit. Just load up all the maps in your state and you should be fine.

Also, is it possible to view all of the above 3 maps simultaneously on a Colorado?

No. You can use Topo Plus and one of the other products at the same time. Topo Plus are transparent maps and show the other maps that are underneath Topo Plus.

[Gee_You Patrol]

You can load up to 389 megs of mapdata on the main unit and the rest onto the SD card

[Dooghan]

Although its got plenty of memory (4GB SD HC card)

You only mentioned your SD card in the first post. Are you saying that you are splitting the maps across the main memory and the SD card? I don't know how that would work. The Explorer maybe able to shed some light on it. All of Garmin's other GPS's suffer from the above limit so I would think it would be the same for the Colorado. I more then happy to be corrected.