What distinguished Eniac from the others was that a working machine performing thousands of calculations a second could be easily reprogrammed for different tasks. It was a breathtaking enterprise. The original cost estimate of $150,000 would rise to $400,000. Weighing in at 30 tons, the U-shaped construct filled a 1,500-square-foot room. Its 40 cabinets, each of them nine feet high, were packed with 18,000 vacuum tubes, 10,000 capacitors, 6,000 switches and 1,500 relays. Looking at the consoles, observers could see a tangle of patch cords that reminded them of a telephone exchange.