The practice of simulating real world systems on computers is widespread and forms an important aspect of many different disciplines. A simulation model provides a simplified view of a real world system facilitating interaction with key aspects of a system without the distraction of unnecessary detail. This thesis is concerned with the role of simulation in computer architecture design. It is recognised that use of simulation in the design lifecycle is expensive and has tended to focus upon the register transfer (RT) level of design. The majority of design projects have no need for fully articulated models in the initial stages: the designer is more involved with fundamental decisions typically based upon choice of algorithm and high-level performance analysis. However, it has been shown that representation of systems in a more abstract form than that found at the RT level can be problematic in terms of reusability. Following an overview of current simulation techniques and software, extensions to the HASE simulation environment are proposed that classify simulation components according to their communication interfaces. This facilitates the loose coupling of simulation entities and consequently promotes component reuse. In addition, the problem of allowing entities represented at different levels of architectural abstraction to communicate was examined and a technique developed to allow entities to negotiate a level of service. The MEDL and EDL languages were developed to enhance HASE's component library and project storage facilities; other software tools allowing the visualisation of a hierarchical model in terms of communication and abstraction were also developed. Various model libraries were developed to investigate the trade-offs between model accuracy, runtime and flexibility afforded by the new techniques. It was demonstrated that the developed techniques facilitate component reuse and offer potential runtime reduction.