Dual screen

[Jack_O'neill]

Ok, I understand what you are saying now. And the answer is yes, you can do that in AutoCAD, but it doesn't look quite a neat as Microstation does it. In the pic below, I have 15 drawings open at the same time. To manually change the size of the windows, just drag the edges around.

I think what got us both confused is the different definitions of the term "viewport". In AutoCAD, viewports will give you different views of the same drawing. If you want more than one drawing open, you do that in different "windows". This is called "tiling" the windows.
screenshot.jpg

[Jack_O'neill]

This is an example of 3 viewports looking at the same drawing:
screenshot2.jpg

[Jack_O'neill]

If you get more than 2 or 3 drawings open at once, it becomes far easier to maximize one of them, and then switch between them as needed. One method for doing that is by using this menu:
screenshot3.JPG

This menu is also where you tile the windows if you wish, lock thier positions and an assortment of other options.
You are limited in how many you can open only by how much your ram and processor will stand.