Mechanical teleprinters using 5-bit codes (see Baudot code) typically used a stop period of 1.5 bit times.[1] Very early electromechanical teletypewriters (pre-1930) could require 2 stop bits to allow mechanical impression without buffering.[citation needed] Hardware which does not support fractional stop bits can communicate with a device that uses 1.5 bit times if it is configured to send 2 stop bits when transmitting and requiring 1 stop bit when receiving.