Speed and Accuracy Capabilities of a Computer

A computer works one step at a time. It can add and subtract numbers, compare letters to determine alphabetical sequence, and move and copy numbers and letters. There is nothing so difficult in these operations. What is significant is the computer's speed. The time required for computer to execute such basic operation as adding and subtracting varies from a few microseconds (millionths of a second) for small machines to 80 nanoseconds (billionths of a second) or even less for large ones. Fractions of a second is given below:

Unit of Time                                                                           Part of a Second

Millisecond (ms)                                                       One-thousandth (1/1,000)

Microsecond (µs)                                                     One-millionth (1/1,000,000)

Nanosecond (ns)                                                      One-billionth (1/1,000,000,000)

Picosecond (ps)                                                       One-trillionth (1/1,000,000,000,000)