There have been languages designed for verifiably safe, hard realtime operations. The most interesting one among them is probably Esterel[1] (that compiles to C or even VHDL/Verilog), though I think the language has mostly been supplanted by graphical representations[2]. I believe that such development environments (and other relatively expensive ones like Ada and realtime Java) are mostly used in aviation/defense. I don't know whether it's due to tradition or cost.

[1]: http://en.wikipedia.org/wiki/Esterel

[2]: http://www.esterel-technologies.com/products/scade-suite/