Hugh Osborne

Teaching computer organization/architecture with limited resources using simulators

As the complexity and variety of computer system hardware increases, its suitability as a pedagogical tool in computer organization/architecture courses diminishes. As a consequence, many instructors are turning to simulators as teaching aids, often using valuable teaching/research time to construct them. Many of these simulators have been made freely available on the Internet, providing a useful and time-saving resource for other instructors. However, finding the right simulator for a particular course or topic can itself be a time-consuming process. The goal of this paper is to provide an easy-to-use survey of free and Internet-accessible computer system simulators as a resource for all instructors of computer organization and computer architecture courses.

A Case Base Similarity Framework

Case based systems typically retrieve cases from the case base by applying similarity measures. The measures are usually constructed in an ad hoc manner. This paper presents a theoretical framework for the systematic construction of similarity measures. In addition to paving the way to a design methodology for similarity measures, this systematic approach facilitates the identification of opportunities for parallelisation in case base retrieval.

Similarity Metrics: A Formal Unification of Cardinal and Non-Cardinal Similarity Measures

In [9] we introduced a formal framework for constructing ordinal similarity measures, and suggested how this might also be applied to cardinal measures. In this paper we will place this approach in a more general framework, called similarity metrics. In this framework, ordinal similarity metrics (where comparison returns a boolean value) can be combined with cardinal metrics (returning a numeric value) and, indeed, with metrics returning values of other types, to produce new metrics.

A crowd of little man computers: visual computer simulator teaching tools

This paper describes the use of a particular type of computer simulator as a tool for teaching computer architecture. The Little Man Computer (LMC) paradigm was developed by Stuart Madnick of MIT in the 1960s and has stood the test of time as a conceptual device that helps students understand the basics of how a computer works. With the success of the LMC paradigm, LMC simulators have also proliferated. We compare and contrast the current crowd of LMC simulators highlighting visual features. We found unexpected insights since despite starting with the same paradigm with the same goals, each implementation is distinct with different strengths and weaknesses. It is our intention that interested educators will find this a useful starting point or useful reference for incorporating simulation into their courses.

The postroom computer: teaching introductory undergraduate computer architecture

Undergraduate students often experience difficulty in understanding the basic principles of low level computer operations in introductory courses to computer architectures when these are taught using actual low level programming languages. This is not due to any inherent complexity of the concepts but rather a consequence of assembly language specific details and the need to introduce many concepts simultaneously, such as, for example, data representation, addressing modes and primitive I/O. This paper describes the Postroom Computer, a low level language simulator that not only provides a simple low level language, suitable as an introduction to assembly language programming, but also allows computer architecture concepts to be introduced in an incremental fashion.

LINDA for case base retrieval: a case for extending the functionality of LINDA and its abstract machine

Case based reasoning (CBR) retrieval operations with partial ordering similarity measures have been implemented in LINDA to extract generic operations and identify potential parallelism in CBR. Mapping and reduction operations, and constraint matching versions of all retrieval operations were identified, then implemented in LINDA. Their operational semantics were expressed in terms of the CHAM for Liam (LINDA abstract machine) and refined to produce the basis for efficient, parallel implementations of the operations as additional LINDA instructions. The implementation of the constraint matching operations suggests the use of eval() to achieve process migration in distributed systems, and default local tuple space interaction. It as suggested that the constraint matching instructions replace the basic matching retrieval instructions, as they extend the functionality of the matching process by maintaining atomicity of matching and moving the constraint function from the program to the LINDA kernel.

Determining Redundant Actions in Sequential Plans

Automated planning even in its simplest form, classical planning, is a computationally hard problem. With the increasing involvement of intelligent systems in everyday life there is a need for more and more advanced planning techniques able to solve planning problems in little (or real) time. However, planners designed to solve planning problems as fast as possible often provide solution plans of low quality. The quality of solution plans can be improved by their post-planning analysis by which redundant actions or optimizable sub plans can be identified. In this paper, we present techniques for determining redundancy of actions in plans. Especially, we present techniques for efficient redundancy checking of pairs of inverse actions. These techniques are accompanied with necessary theoretical foundations and are also empirically evaluated using existing planning systems and standard planning benchmarks.

The educational range of visual simulations of the Little Man Computer architecture paradigm

The Little Man Computer (LMC) paradigm was developed at MIT during the 1960s where it was taught to all undergraduate computer science students. LMC consists of a cartoon character inside of a walled room containing mailboxes, a calculator, a counter with an external reset switch, and input/output baskets. Although this analogy between the internal operations of a hypothetical computer and a real computer is not perfect, LMC has proved itself enduring, intuitive, powerful, and an extensible teaching paradigm. In this paper we present a range of visual LMC simulators from K-12 to post-graduate educational levels. In particular we highlight four simulators in detail: (1) a K-12 interactive CD-ROM LMC tutorial; (2) an undergraduate web-based LMC Shock-Wave animated simulator; (3) an undergraduate web-based LMC Java simulator; and (4) an extensible undergraduate/graduate LMC/Postroom computer. Together these simulators provide a powerful selection of tools for illustrating the concepts of computer systems architecture.

BRQS Matching Algorithm for Searching Protein Sequence Databases

String matching algorithms play a key role in many computer science problems, challenges and in the implementation of computer software. This problem has received a great deal of attention due to various applications in computational biology. In our study, we propose a new algorithm called BRQS. Experimental results show that it offers fewer numbers of comparisons and offers improved elapsed searching time when compared to other well-known algorithms for searching any length of alphabets and patterns. The proposed algorithm is applicable to search protein sequence databases as well as any other string searching applications.

Update plans (specification)

Update plans, are a high level language for specifying low level activities. Update plans are amenable to interpretation as declarative specifications of machine state transitions while maintaining a great deal of similarity to low level code, thus allowing for efficient compilation to executable code. The syntax and semantics of update plans are informally introduced. The second half contains a non-trivial example of their application, in which an abstract machine for a simple functional language is presented. Preliminary results for an implementation of this machine, obtained by applying a prototype update plan compiler to the specification, are also presented.<<ETX>>