Depends on the compiler, familiarity with interface, etc, etc. on how quickly I could get up to speed on building a new version.
I graduated from a 4 year program mostly with the typical skill sets and experience of a typical software developer. (C++, VB.Net, Java, COBOL, Assembly, Oracle, Database Design & Management, etc.)
However, the systems programmer position I'm employed for is a proprietary programming language for proprietary hardware. So the general public rarely or never knows about what we program in. It would be nice to regularly use C++,C#, or VB.Net in my daily programming work, but I do what what they pay me to program in.
A lot of what we deal with is a lot of direct hex and binary string processing to communicate with hardware.