Umbriel (moon) that obliterated its older surface. Covered by numerous impact craters reaching in diameter, Umbriel is the second most heavily cratered satellite of Uranus after Oberon. The most prominent surface feature is a ring of bright material on the floor of Wunda crater. This moon, like all moons of Uranus, probably formed from an accretion disk that surrounded the planet just after its formation. The Uranian system has been studied up close only once, by the spacecraft "Voyager 2" in January 1986. It took several images of Umbriel, which allowed mapping of about 40% of the moon’s surface. Umbriel, along with
Oberon (operating system) active Computer Science professors) referred to themselves as 'part-time programmers' in the book 'Project Oberon'. In late 2013, a couple of months before his 80th birthday, Niklaus Wirth published a second edition of Project Oberon. It details the implementation of the Oberon System using a RISC CPU of his own design realized on a Xilinx FPGA board. It was presented at the symposium organized for his 80th birthday at ETHZ. In the meantime several emulators for this version were implemented. According to Josef Templ, a former member of the developer group at Eidgenössische Technische Hochschule, Zürich and later member of