Virtual Hardware for Operating Systems Development

Developing an operating system on bare hardware is difficult due to an inhospitable development environment, long edit-compile-run-debug times, and the need for extra target hardware. This paper contributes general techniques for creating virtual hardware for operating systems development. The virtual machine is realized on top of UNIX and is a close approximation of real hardware, including interrupts, time slicing, virtual memory, devices, multiple processors with separately programmable memory management units, and the ability to run application programs natively. Debugging and testing our operating system in such an environment was considerably quicker and easier compared to developing on bare hardware. 1 Introduction Developing operating systems is difficult on bare hardware. There is a paucity of tools for run time and post mortem debugging, as well as execution profiling. Rapid prototyping requires quick edit-compilerun -debug cycles. Fast turnarounds are a problem when machin..

Adaptation and Synchronization in Bandwidth-Constrained Internet Video and Audio

Systems for the real-time transmission of video and audio on low-bandwidth lines must account for the limited bandwidth available, the bandwidth variance, packet loss rates, as well as CPU load. Vosaic, short for Video Mosaic, integrates real-time continuous media within standard Web pages, and handles the issues of transmitting continuous media with the Video Datagram Protocol (VDP). VDP dynamically adapts the media stream to the available network and CPU bandwidth, thus improving video performance. Built as an object-oriented framework, Vosaic permits the easy addition and customization of the basic VDP protocol for different media types. This family of protocols currently support two different standard video formats, as well as four audio formats. 1 Introduction Early systems for the delivery of real-time video and audio on the Internet, such as Berkeley's CM Player[12], required high-end workstations and high-speed Ethernet or T1 data rates. These systems concentrated on transmitt..

Customizable Object-Oriented Operating Systems

This article offers our solution to the problem of building customizable operating systems and describes the results achieved in implementing a customizable operating system. We have built an object-oriented, customizable operating system, Choices [3, 4]. We advocate object-oriented programming to structure customizable operating systems, and Choices is designed as an interacting collection of object frameworks. Descriptions of Choices, of framework methodology and its application to OS subsystems is given in the next section. Structuring the system as a set of frameworks facilitates the design, maintenance, and extension