Developing Point-of-sale Applications for CE and Embedded

Any one know how prevalent Windows CE and or Embedded is in the point-of-sale systems market? I'm interested in developing an application for that market and it is not clear if CE and or Embedded are widely used.

How one would go about developing a third party application for Windows CE and or Embedded? Is it possible to develop applications for Windows 9x, 2K, CE, Embedded, Pocketpc, Mobile, XP, etc. using a single source? Where does Dotnet and Activex fit into this picture?

The exposure would be limited as the CE system really requires ROM embedding in order to maintain viability, and that goes beyond simple app development.

You can do it, you have access to the CE SQL Server and SQL Server ADO connectivity to front-end the DBMS. You cannot create a single source base between Win32 and CE, however you can get close to it if you use .net - close, but there will still be porting (unless you stick only to common API's).

CE has ActiveX just like Win32, however they have to be WinCE controls, which means Win32 > CE ports or dll's that have already been ported.