sentences:  As a result of implementing the MDC as an I/O device, the Firefly supported multiple display controllers in one system connected to multiple monitors.Two of the variants of the Firefly used system software called "Topaz", which consisted of multiple components such as the "Taos" operating system that used a microkernel named "the Nub" and the "Trestle" window system.One of the features of Taos was that it supported the Ultrix binary calling interface, allowed existing Ultrix binaries compiled for the MicroVAX run unmodified image on the Firefly.