Data transfer rate of a tape is the number of characters transmitted per second from the tape to primary storage. We measure it in bytes per second (bps). Its value depends on data recording density and speed of tape movement under read/write head. Tape speed is typically of the order of 100 inches per second. Hence, for a tape having data recording density of 77,000 bpi and its drive having tape speed of 100inches per second, data transfer rate is 77000×100=77,00,000 bytes or roughly 7.7 MB per second.
The data transfer rate is commonly used to measure how fast data is transferred from one location to another. For example, a hard drive may have a maximum data transfer rate of 480 Mbps, while your ISP may offer an Internet connection with a maximum data transfer rate of only 1.5 Mbps. Data transfer rates are typically measured in bits per second (bps) as opposed to bytes per second, which can be understandably confusing. Because there are eight bits in a byte, a sustained data transfer rate of 80 Mbps is only transferring 10MB per second. While this is confusing for consumers, Internet service providers must enjoy measuring data transfer rates in bps since it makes their Internet access speeds sound 8x faster than they really are.
A data transfer rate tells you how much digital data will travel from one place to another—from a hard drive to a USB flash drive, for example—in a specific period of time. Rather confusingly, you’ll see it measured in -
bits per second
bytes per second
The difference between bits and bytes is explained below. However, with today’s technology being capable of transferring large amounts of data at fast speeds, you’re more likely to see it measured in megabits per second (Mbps) or megabytes per second (MBps). (A megabit is around a million bits. A megabyte is roughly a million bytes.) Sometimes—when downloading a file from the internet, for instance—you might see the data transfer rate measured in kilobytes per second (KBps).