This is opinion and observation over 36years of computing I've been hands on with. The term "large frame" is any computer that is not a micro but includes examples like the LSI-11 which was the cusp of mini to micro. Micro is specifically anything that exists as a chip fromthe basic 8bitter 8008, through the non racked Pentium. Fortran is definately one of the languages. There are many languages based on or spawned from it. FOCAL comes to mind as a varient. Just about any multipurpose cpu has Fortran for it. Considered a large frame language by many but the major micros have compilers too. The legacy of Fortran is is number crunching in all its forms which covers a lot of ground. The most strongly held ground I've seen is numerical modeling. BASIC is another widespread language. Likely the second most(runs neck and neck with fortran) widely ported to micro and large frame processors. The legacy of BASIC is one language, billions of dialects. BASIC runs from interger minimum subsets to full bore structured languages with data typing to the fully visual forms that do not look like BASIC at all. Those two alone run close to assembly in frequency of occurance for any cpu. For "systems work" it would appear C is it. Though C is a common cross compiled language for wide variety of embedded cpus. The biggest assumption I've seen with C is that it's likely in or around a unix (or unix like) environment for use or development. Since the mid 80s that is less so. Once you get past those the what language for what work tends to stratify based on application and preference. Allison