The longest survival time for a human-made object on Venus was 127 minutes, back in 1981 when the Soviet spacecraft Venera 13 landed there. Not dying for two hours, and netting our first ever colour photos of the planet's surface, was considered a huge success; the probe had only been designed to live for 32 minutes before it was cooked, crushed, and dissolved by its environs. Three more spacecraft followed, all Soviet—Venera 14, Vega 1, Vega 2—but we haven't tried to land anything on Venus since 1985.
One of the core problems of exploring Venus is that normal digital computers don't really work there. Standard silicon chips can hang in to around 250°C, but eventually there's just so much energy in the system that the silicon stops being a semiconductor—electrons can freely jump the bandgap—and everything stops working. The Venera landers kept their electronics cool with cumbersome hermetically sealed chambers, and sometimes the innards were also pre-cooled to around -10°C before being dropped into the atmosphere by the parent orbiter.
Over the last few years electronics based on the semiconductor silicon carbide (SiC) have started to mature. SiC has drawn a lot of interest from the military and heavy industries because it can support very high voltages and temperatures—and those properties make it a very suitable candidate for computing on Venus, too.
