Our initial SBus interface was base on the MIT-brewed Transit SBus Interface:
"This note describes a simple SBus interface designed for providing interfacing from an SBus based machine ( e.g. Sparcstations) to various custom hardware. This interface was designed primarily for communication with boundary-scan controllers and Transit nodes (tn38). Nevertheless, it uses a minimal asynchronous interface making it suitable for providing simple interfacing to many devices. The over-riding goals in this SBus interface implementation were to keep the design simple and build it quickly. The interface is an SBus slave card which supports only single-word read and write operations. The interface card itself includes a boundary-scan controller which supports two independent boundary scan paths. "
We implemented an interface between an "Argus" version of the IKOS VirtuaLogic Emulator and a Transit Sbus card, providing a 24 bit address, 32 bit data connection that was directly read and written via memory-mapped on a host SPARC10 workstation. We successfully operated the interface in the 100KHz to 1MHz range for certain designs.
We abandon this interface when upgrading to a "Hermes" version VirtuaLogic emulator in favor of the commercially available SLIC EB-1 Sbus interface.