Complex sentence: Each machine used 55,000 vacuum tubes, about ½ acre (2,000 m²) of floor space, weighed 275 tons and used up to three megawatts of power, although the failure rate of an individual tube was low due to efforts in quality control.
Split into simpler sentences: Each machine used 55,000 vacuum tubes, about ½ acre (2,000 m²) of floor space, weighed 275 tons and used up to three megawatts of power. Although the machines used a large number of vacuum tubes, the failure rate of an individual tube was low due to efforts in quality control.