The 726 used half-inch tapes with seven tracks. Six were used for data and the seventh was a parity track. Data was stored as six-bit characters, one to a track, for a total storage density of 100 bits per linear inch.
A unique control system developed for the 726” which meant “a tape reached full speed in 1/100th of a second, or before moving half an inch,” and important feature as the drive started and stopped during operations. Once the tape reached its top speed of 75 inches per second it could “read or write at a rate of 12,500 digits a second.” more> http://tinyurl.com/cs4bk74