1. A computer-implemented method comprising: launching an operating system for the computer, wherein: the operating system is a non-multi-tasking operating system that can run only a single task at a time; the operating system has an application layer; and the operating system further comprises: one or more protocol stacks; and an inter-task communication mechanism for communicating between the first task and the one or more protocol stacks; running a first task in the application layer, wherein the first task includes an application manager and the first task is not an operating system; launching two or more applications inside the first task, wherein the two or more applications run concurrently under the control of the application manager; and maintaining, by the application manager, a stack of application descriptors, wherein: each of the two or more applications has a corresponding application descriptor in the stack, wherein the application descriptor provides details about the corresponding application; and each application descriptor provides access to and control of a set of one or more forms associated with the corresponding application, wherein a form, different from an application descriptor, defines an image displayed on a screen.