Jos asks: Undoubtedly tape is cheaper (not just per byte but also per drive) but it's not random access. Clever things were done with tapes, usually in batch mode. The RAMAC made it possible to think that multiple files (not in the computer sense but in the business sense) could be updated simultaneously in real-time. It is a fallacy to confuse the cost of a storage unit with the value that The data on it provides. Clearly as the cost of storage has dropped new applications that previously weren't economically feasible open up. e.g. When I got started in digital music in the 80's, the most technically advanced mixing systems began using hard drives instead of tape for digital music storage and manipulation. Tim.