I deliberately picked my examples--"memory chip," "salt water taffy" and "space shuttle communication headquarters"--to illustrate the shifting paradigm. We've got an endless list of fairly contemporary compound nouns that are built entirely from nouns. Business suit, dog food, fuel tank, power company, bird cage, lawn mower, motor vehicle, office work, computer science, government program, food stamp, gas pedal, air conditioner, water heater, sump pump... Food alone would fill a book: chicken dinner, pea soup, turkey bone, pepperoni pizza, chocolate candy, birthday cake, potato salad, tomato sauce, rye bread, cheese omelet, champagne breakfast, pastrami sandwich...
"I make my living selling computer memory" sounds better and everyone would understand you mean plural. I make my living selling candy. I make my living selling candies. That is functionally plural either way and either version sounds right. I make my living selling peach. No thats wrong. It must be I make my living selling peaches. I make my living selling garlics. No that is wrong. For some reason there is no such thing as garlics. It must be I make my living selling garlic. I make my living selling clothing. I make my living selling clothings. I make my living selling clothes. I make my living selling cloth. I make my living selling cloths. You can't sell one clothe. Selling cloth and selling cloths are both plural but mean different things. I make my living selling iron. I make my living selling irons. I make my living selling fruit. I make my living selling fruits. Both are valid. Selling fruits feels more hands on than selling fruit does. I picture the guy selling fruits as working at a stand in the farmers market while the guy selling fruit sounds like he just buys and sells shipping containers of fruit that he never sees while sitting in his office.
Latin isn't a language I have studied intensely. But no, that's Spanish. In Latin it would be memoriae. But be careful. "Memory" has two meanings in English. One is the mental ability to remember, which occurs only in the singular. The other is a specific thing that is remembered, and that can have a plural. I don't know that the Latin word memoria carries both meanings. There might be another word for something that is remembered. Perhaps recordatio.
