Hardware-software Interaction Research Articles

A performance model for hardware/software issues in computer-aided design of protocol systems

Protocol execution can run into bottlenecks which are due to implementation decisions rather than to the protocol rules. The performance effects of processor saturation, buffer management strategy, allocation of functions between host and front-end, and hardware-software interactions due to special hardware attributes can, in principle, be predicted at the design stage by analytic performance models. The paper describes the process of construction of such a model for the data transfer stage of a simple transport protocol resembling an OSI class 4 protocol, including queueing for critical sections which protect the buffer pools and connection state information. The model is part of a computer-aided design process for communications systems, currently under development.

Software for a Microcomputer Controlled Laser Synchronization System

The paper presents the software development project for a microcomputer controlled laser synchronization system. The development is presented in the light of modern software engineering practice. The modular approach is used, where the whole software system is developed as separate modules. All modules can later be independently maintained and modified. Each module is subdivided into separately accessible procedures. The hardware-software interaction is stressed by the presentation of a Phase Lock Loop subsystem in this project. Flow diagrams of a selected software module and one of its procedures are presented.

Hardware-software interactions in SYMBOL-2R's operating system

This paper describes the chief attributes of the Virtual Processor placed at the disposal of each user of the SYMBOL-2R time-shared multiprocessor system, and the mechanisms by which SYMBOL's hardwired operating system manages processing-mode transitions for individual Virtual Processors and allocates hardware resources -- processors and memory space -- among competing Virtual Processors. It describes the provisions by which the unusually high-level capabilities of the hardware are augmented by software, and contrasts the structure of the software component of the operating system with that of the hardware component. Finally, it describes the hardware/software partition of resource-allocation functions, in which allocation policies are controlled by software and executed by hardware.