"The typewriter employed 36 keys divided into four banks: the first was numbered 0 through 5, and the other three were numbered 0 through 9. To type a character, the operator simultaneously pressed one key from each bank. Each four-digit combination corresponded to one of 5,400 Chinese characters, punctuation marks, numerals, letters of the English alphabet and other symbols etched onto a revolving drum which had a diameter of seven inches and a length of 11 inches. The drum made a complete revolution once per second, allowing the operator to achieve a maximum typing speed of 45 words per minute."
A Professor's Hunt for the Rarest Chinese Typewriter