Thesis (Ph. D.)--University of Wisconsin--Madison, 1980. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Bibliography: leaves 162-176.

No description available.

This thesis describes the evaluation of four operating systems for microcomputers. The emphasis of the study is on the suitability of the operating systems for use in real-time applications, such as process control. The evaluation was performed in two sections. The first section was a quantitative assessment of the performance of the real-time features of the operating system. This was performed using benchmarks. The criteria for the benchmarks and their design are discussed. The second section was a qualitative assessment of the suitability of the operating systems for the development and implementation of real-time systems. This was assessed through the implementation of a small simulation of a manufacturing process and its associated control system. The simulation was designed using the Ward and Mellor real-time design method which was extended to handle the special case of a real-time simulation. The operating systems which were selected for the study covered a spectrum from general purpose operating systems to small, specialised real-time operating systems. From the quantitative assessment it emerged that QNX (from Quantum Software Systems) had the best overall performance. Qualitatively, UNIX was found to offer the best system development environment, but it does not have the performance and the characteristics required for real-time applications. This suggests that versions of UNIX that are adapted for real-time applications are worth careful consideration for use both as development systems and implementation systems.

Continuing advances in hardware and in software applications are pushing traditional operating systems beyond their limits. This is largely due to the fact that these advances, and their associated requirements, were not foreseen at operating system design time. This becomes particularly apparent with multimedia applications, whose demands for guaranteed quality of service differ considerably from those of most traditional applications. To ensure that many future requirements will be met, along with many existing demands, one solution is to allow applications to customize their operating system throughout its life-time. However, opening up an operating system to application-initiated changes can compromise the integrity of the system, suggesting the need for a security model. Like any other aspect of a customizable system, such a security model should be securely customizable, too. Therefore, this dissertation introduces MetaOS, a securely- and dynamically-customizable operating system which has a securely- and dynamically-customizable security model. MetaOS employs four types of building blocks: meta-levels, meta-spaces, meta-objects, and meta-interfaces. Meta-levels localize customizable system services. Meta-spaces act as firewalls which prevent custom alterations from affecting unrelated meta-spaces and their applications. Meta-objects help to modularize meta-spaces into smaller, easier-to-maintain components. Finally, meta-interfaces provide the heart of the secure customizing model. MetaOS meta-interfaces are strictly divided into declarative and imperative interfaces, providing a basis on which to distinguish between calls which only affect the invoking application (i.e., local-effect calls), and calls which could affect other applications as well (i.e., meta-space-wide-effect calls). By giving free access to the former, but limiting access to the latter, a basic balance between flexibility and security can be struck. Additional flexibility is achieved by allowing new local and meta-space-wide-effect calls to be added dynamically, by permitting untrusted applications to negotiate changes with trusted meta-space managers, and by allowing untrusted applications to migrate to cloned meta-spaces and alter them as necessary. / Graduate

No description available.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Lizy K. John. Vita. Includes bibliographical references. Also available from UMI.

Approved for public release, distribution is unlimited / The subversion technique of attacking an operating system is often overlooked in information security. Operating Systems are vulnerable throughout their lifecycle in that small artifices can be inserted into an operating system's code that, on command, can completely disable its security mechanisms. To illustrate that this threat is viable, it is shown that it is not difficult for an attacker to implement the framework for the "two-card loader" type of subversion, a trap door which enables the insertion of arbitrary code into the operating system while the system is deployed and running. This framework provides several services such as memory allocation in the attacked system, and mechanisms for relocating, linking and loading the inserted attack code. Additionally, this thesis shows how Windows XP embedded designers can use Intel's x86 hardware more effectively to build a higher assurance operating system. Principles of hardware support are discussed and recommendations are presented. Subversion is overlooked because critics believe the attack is too difficult to carry out. It is illustrated in this thesis that this is simply not the case. Anyone with access to the operating system code at some point in its lifecycle can design a fairly elaborate subversion artifice with modest effort. / Ensign, United States Navy Reserve

by Ma Hon-chung. / Bibliography: leaves [199]-[204] / Thesis (M.Ph.)--Chinese University of Hong Kong, 1984

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Typescript (photocopy). / Digitized by Kansas Correctional Industries