An alternative is attempted to the bus-switch for bus cycle emulation, preferably one that was programmable, so as to minimize the amount of hardware to be designed for each microprocessor to be emulated. The evolution of the hardware architecture from the basic concept is discussed first, followed by a discussion of issues involved in programming the emulation. A problem-solution format is used to present each topic; problems that arise are described, and then proposed solutions are explained.>

Virtual Instruments1 is an experimental programming environment for developing electronic test and measurement (T&M) applications. Intended users are test engineers, who are not programmers, but computer literate domain specialists. Unlike traditional programming environments, that provide weak support for a broad range of applications, virtual instruments provides strong support for a specific application. The programming paradigm is bottom-up synthesis of layers of virtual machines — called virtual instruments — using human interface models from the application domain, so that software development occurs without writing code. The object-oriented view of the world has proven a natural fit. Implementation was in Berkeley Smalltalk on a SUN workstation.