Software
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. In contrast to Ultrix, Topaz supported processes with multiple threads which could span multiple processors, and the Taos system could run both Ultrix and Topaz applications at the same time. Modula-2+, (a Modula-2 extended language) was used to program both Topaz and its applications.
Read more about this topic: DEC Firefly