In the Sixtys Digital Equipment Corporation used Western Union Teletypes as terminals. The New York Stock Exchange also uses a 6-bit code for its automated postings. It is the only true 8-bit code standard. To limit cable costs, all telecommunication equipment uses multiplexing. A telegraph provide the simplest example.
Morse code employs a series of dots and dashes to represent a character.
Dots are short pulses of electrical current compared to the longer dash pulses. In modern telecommunications, pulses are usually the same duration and a group of pulses are sent together to represent one character code. A pulse can only be in one of two states but there are many names for the two states. If the mark condition appears, a logical one is recorded otherwise a logical zero. Figure 1 shows this multiplexing format.