Teleprinter - History

History

The teleprinter evolved through a series of inventions by a number of engineers, including Royal Earl House, David Edward Hughes, Emile Baudot, Donald Murray, Charles Krum, Edward Kleinschmidt and Frederick G. Creed.

By 1846, the Morse telegraph service was operational between Washington, D.C., and New York. Royal Earl House patented his printing telegraph that same year. He linked two 28-key piano-style keyboards by wire. Each piano key represented a letter of the alphabet and when pressed caused the corresponding letter to print at the receiving end. A "shift" key gave each main key two optional values. A 56-character typewheel at the sending end was synchronised to coincide with a similar wheel at the receiving end. If the key corresponding to a particular character was pressed at the home station, it actuated the typewheel at the distant station just as the same character moved into the printing position, in a way similar to the daisy wheel printer. It was thus an example of a synchronous data transmission system. House's equipment could transmit around 40 instantly readable words per minute, but was difficult to manufacture in bulk. The printer could copy and print out up to 2,000 words per hour. This invention was first put in operation and exhibited at the Mechanics Institute in New York in 1844.

Landline teleprinter operations began in 1849 when a circuit was put in service between Philadelphia and New York City.

In 1855, David Edward Hughes introduced an improved machine built on the work of Royal Earl House. In less than two years, a number of small telegraph companies, including Western Union in early stages of development, united to form one large corporation – Western Union Telegraph Co. appeared to carry on the business of telegraphy on the Hughes system.

Émile Baudot designed a system using a five unit code in 1874. The Baudot system was adopted in France in 1877, and later extensively in France. The British Post Office adopted the Baudot system for use on a simplex circuit between London and Paris in 1897, and subsequently made considerable use of duplex Baudot systems on their Inland Telegraph Services.

During 1901 Baudot's code was modified by Donald Murray (1865–1945), prompted by his development of a typewriter-like keyboard. The Murray system employed an intermediate step, a keyboard perforator, which allowed an operator to punch a paper tape, and a tape transmitter for sending the message from the punched tape. At the receiving end of the line, a printing mechanism would print on a paper tape, and/or a reperforator could be used to make a perforated copy of the message. As there was no longer a direct correlation between the operator's hand movement and the bits transmitted, there was no concern about arranging the code to minimize operator fatigue, and instead Murray designed the code to minimize wear on the machinery, assigning the code combinations with the fewest punched holes to the most frequently used characters. The Murray code also introduced what became known as "format effectors" or "control characters" – the CR (Carriage Return) and LF (Line Feed) codes. A few of Baudot's codes moved to the positions where they have stayed ever since: the NULL or BLANK and the DEL code. NULL/BLANK was used as an idle code for when no messages were being sent.

In 1902, electrical engineer Frank Pearne approached Joy Morton, head of Morton Salt, seeking a sponsor for research into the practicalities of developing a printing telegraph system. Joy Morton needed to determine whether this was worthwhile and so consulted mechanical engineer Charles Krum, who was vice president of the Western Cold Storage Company. Krum was interested in helping Pearne, so space was set up in a laboratory in the attic of Western Cold Storage. Frank Pearne lost interest in the project after a year and left to get involved in teaching. Krum was prepared to continue Pearne’s work, and in August, 1903 a patent was filed for a ‘typebar page printer’. In 1904, Krum filed a patent for a ‘type wheel printing telegraph machine’ which was issued in August, 1907. In 1906 Charles Krum's son, Howard Krum, joined his father in this work. It was Howard who developed and patented the start-stop synchronizing method for code telegraph systems, which made possible the practical teleprinter.

In 1908, a working teleprinter was produced by the Morkrum Company, called the Morkrum Printing Telegraph, which was field tested with the Alton Railroad. In 1910, the Morkrum Company designed and installed the first commercial teletypewriter system on Postal Telegraph Company lines between Boston and New York City using the "Blue Code Version" of the Morkrum Printing Telegraph.

In 1916, Edward Kleinschmidt filed a patent application for a typebar page printer. In 1919, shortly after the Morkrum company obtained their patent for a start-stop synchronizing method for code telegraph systems, which made possible the practical teleprinter, Kleinschmidt filed an application titled "Method of and Apparatus for Operating Printing Telegraphs" which included an improved start-stop method.

Instead of wasting time and money in patent disputes on the start-stop method, Kleinschmidt and the Morkrum Company decided to merge and form the Morkrum-Kleinschmidt Company in 1924. The new company combined the best features of both their machines into a new typewheel printer for which Kleinschmidt, Howard Krum, and Sterling Morton jointly obtained a patent.

In 1924 Creed & Company, founded by Frederick G. Creed, entered the teleprinter field with their Model 1P, which was soon superseded by the improved Model 2P. In 1925 Creed acquired the patents for Donald Murray's Murray code, a rationalised Baudot code, and it was used for their new Model 3 Tape Teleprinter of 1927. This machine printed received messages directly on to gummed paper tape at a rate of 65 words per minute and was the first combined start-stop transmitter-receiver teleprinter from Creed to enter mass production.