Specifying the System
Customizing the Windows CE system is a matter of selecting the software components and modules that will be included in your image. For example, if you are producing a network driver for your hardware, which presumably has an Ethernet interface, you will need to add a networking stack (or two) to the system. If TCP/IP is your protocol of choice, you will need to add the TCP/IP module to the list of modules in the system. This process will need to be carried out until you get an operating system that will provide all the interfaces and features that your target hardware will require.
Once you have a list of essential software components that are required for your device, you can start sizing your memory requirements. Jot down the list of software components and modules, and write down its estimated size. You can check the size of a module by simply looking at the size of the file itself. Software components are a bit trickier because they add up to form a module. You should actually build the Windows CE system, and look at the size of the resultant module to determine its memory requirements. Once you have this list ready, you will get a fair idea of the size that the Windows CE system will occupy. Of course, you don't have a good idea of what the drivers and applications are going to needbut you have something to work with. By studying similar drivers provided for your prototype environment, if one is available, further estimates can be created. You will at least have a ballpark figure that will allow you to make sure that the RAM and ROM requirements of your hardware are not completely off the mark.