A - This depends on two things:
1) Do you intend to load large images? Generally speaking you need enough memory for your operating system (discussed below), the application and associated libraries, and the map layers you
are rendering. SHP files require very little memory unless there are many associated labels. Labels take up a lot of memory and you should minimize the number displayed at any one time.
Raster images can generally be thought of as requiring as much memory as their size. So, for example, a 1 GB raster requires 1 GB memory.
So as an example, lets say you have a dozen SHP layers and a 500MB raster image. In general terms you will need 500MB for the image, approximately 100MB for the application and approximately
50MB for the remaining layer rendering including labels. The total is 650MB. However, this does not represent how much the operating system requires.
2) If you are using Windows XP and run a clean system (meaning no concurrent applications or memory resident items), expect XP to take up about 200MB of Ram. Add this to the above numbers and
you are up to 850MB. Could you get by with 1GB. Yes but it would be cutting it close.
If you run some tests on Vista, its pretty disturbing. Immediately after booting, run task manager and you will see where you are using about 1GB of RAM (if you run a very clean system,
meaning you run no background applications). This means that 1GB is being used just to run the operating system (and other essentials like virus scan). Now do the math with the numbers in
item 1 and you can see where you will have dicey results with 2GB of Ram. It would seem 4GB is best.
Finally, you might hear about the fact that you can add memory to a PC running Vista by plugging in a memory stick. This method of adding memory is pretty much a joke. Yes it provides more
apparent 'Ram' but it is only OK with slow reads, not where random read/write is required. It turns out, most memory is accessed in this manner so this feature is pretty much uselees.
