I always assumed it came from big international physics experiments where English is most people's second language. People who learn to program in an expat community are going to pick up some jargon that will sound weird to native English speakers in California.

I wonder if this used to be the more common term, and at some point we switched to “code”. Physicists were among the first serious computer users, but their software culture may have bifurcated from ours at some point.