QUADDOS : A MULTIPROGRAMMING KERNEL FOR PCs

Abstract

Multiprgramming operating systems allow the user to run several programs concurrently. In this disserta-tion a multiprogramming layer is developed on top of WS—DOS for IBM—PC compatibles. Various management activities such as, switching the CPU between process, scheduling, loading and initiating programs and process termination are implemented. Round—robin CPU scheduling algorithm is used with a time quan-tum of one third of a second allocated to each process. To facilitate the user interface of each process, the display screen of PC is divided into five windows of which one is allocated permanently to the scheduler, which runs as process zero. Window management system is developed, which is an extension of the notion of multi-programming system, to provide a better, more simulta-neous, and more intuitive presentation of the information displayed by the multiple programs running on the system. iridow management includes the methods of representing windows, mapping from Virtual video displays to real video displays, interfacing the window manager to the basic system functions provided by the PC hardware and resident operating system, and management of the keyboard within a multiple—window context.