For several decades, people who wanted to communicate with each other used devices called teletypes, which were essentially an electromechanical typewriter with output on paper spools.
What is Teletype?
A teletype (teletype writerOr teleprinterOr teletype ή TTY) is a telephone communication device that allows operators to send and receive text messages using the typewriter keypad and printed paper as output.
The term "teletype" originated as a trade name by the Teletype Corporation in 1928. Teletype Corporation's products became so well-known and ubiquitous that "teletype" evolved into a generic term, synonymous with "teleprinter", especially in the computer field.
To understand the basic principle behind teletypes, imagine two electric typewriters connected by wires (or a wireless radio link). Whatever you type on one typewriter is automatically printed on the other. Now imagine that these two typewriters can be miles apart, thanks to wired networks or radio transmissions. You may be aware of what a communication revolution these machines represented in the early 20th century.
The output of a teletype was a roll of paper cut by the operator, depending on the size of the message,
The earliest teletypes were teleprinters . They first appeared in the 1840s and provided an advantage over Morse code telegraphs in that the output of a teletype was immediately human-readable without the need for special training.
A system of two teleprinters, with one operator trained to use a keyboard, replaced two trained Morse code operators , and news could be sent instantly around the world.
In the early 1900s, these original telexes became more reliable and easier to use, replacing their original piano keyboard with the well-known QWERTY keyboard and the ability to record messages on tape for repeated transmission.
And of course the ancestors of teletypes were telegraphs , which were machines that sent messages in Morse codes by interrupting or allowing current to pass through a power source. Their output was a long thin ribbon of paper, on which the dots of Morse code were engraved.
Why did people use computer telescopes?
Until the advent of screens, people on early computers used the telephone as a means of writing and receiving messages and results to and from the computer.
To imagine why a teletype would be useful with a computer in the 1920s, remember these two remotely connected typewriters from the last example and replace one with an interactive computer system. Instead of communicating with a remote telex, you send and receive human-readable text to and from a computer.
The computer could be in the same room, in another part of a building, or even in the middle of the world, as long as it is connected via a telephone network.
Many large computer systems (especially those sold by IBM) operated without interaction, in a standard batch mode , which meant that a single program would be typed onto punch cards , the punch cards and the single program would wait their turn along with other users' programs.
When it was his turn, the punch cards would be fed to the computer, the program would run and the results would be written to another stack of punch cards. The punch cards with the results would then be read by the teletype that would print the results in a human-readable format.
Alongside computers operating in batch mode in the mid-1950s, engineers began experimenting with interactive computers, where a computer operator could provide data and get results in near real time in a kind of interactive "conversation" with the machine. Many of these computers, such as the Bendix G-15 (1956) and the IBM 610 (1954), used modified electric typewriters as input or output devices, which were not necessarily commercial teletypes.
An example of this process is the IBM 610 (1954) pictured below, an early interactive computer that used a modified typewriter to print output results.
The invention of timesharing in 1959 allowed multiple users to share an interactive computer system simultaneously, making low-cost, individual terminals, such as teletypes, desirable for computer use. As this practice became more common in the 1960s, organizations with mainframe computers began to purchase more and more teletype machines for use as terminals.
Teletype Model 33
One of the biggest reasons the term "teletype" was so closely associated with computing was Teletype Corporation Model 33 (also called "ASR 33"), which was first released in 1963. Unlike most other teletypes of that time, the Model 33 could understand ASCII standard, which the American National Institute of Standards had recently developed as standard code for electronic devices and computers. ASCII as a standard adopted by all which allowed many different computer brands to easily communicate with each other.
Popular microcomputers of the late 1960s and early 70s, such as the PDP-8 , PDP-11 , and Data General Nova , supported ASCII encoding, making the Model 33 an ideal low-cost input/output and terminal for them. In particular, DEC's PDP series were influential machines, and if you look at historical photos of them, you will almost always see a Teletype Model 33 in use alongside them.
When you used a telegram with a host like this, you saw your own local paper input as you typed, and then received a response from the computer that printed below your text, as the teletype prints on a continuous roll of paper. which is stored inside the unit.
In 1970, Dennis Ritchie and Ken Thompson developed the UNIX operating system on a PDP-11 using the Teletypes Model 33 teletype. The terms “TTY” in Linux, the Terminal application on Macs, and even, to some extent, the command line in Windows 10 , all share the same lineage as the linear (line-by-line) text output that originated on teletype computers.
The age of video games
It is worth noting that the teletype era produced a number of classic text-only games that went on to influence the video and computer game industries for a long time. Notable examples include Zork, Lunar Lander, Hunt the Wumpus, Star Trek, and The Oregon Trail. All of these were originally played as text-only games with typed messages and output printed on teletype paper.
Why did people stop using telescopes with computers?
Although they have been popular for some time, teletypes have had some major drawbacks as computer terminals. It was very noisy due to the mechanical action of the impact head, which hit the paper. They were also slow, often limited to about 10 characters per second. And lastly, you had to use a lot of paper.
In the 1960s, companies such as IBM began experimenting with computer terminals that used CRT screens instead of paper for output. These early "glass teletypes" sought to provide faster interaction speeds and save money on paper consumption.
While at least three manufacturers produced keyboard-equipped terminals by 1970, each cost significantly more than a Teletype Model 33. In 1974, Hewlett-Packard sold a branded version of the pioneering Datapoint 3300 terminal called the HP2600A for $4.250 . At the same time, a Teletype Model 33 cost about $755 to $1.220 depending on its capabilities, representing a significant savings.
But the price of keyboard-based display terminals fell dramatically in the 1970s, having slipped to around $800 per unit by 1980 (depending on its capability). Around that time, the well-respected DEC VT-100 terminal typically sold for around $1.550.
As soon as the price of keyboard terminals dropped and they exceeded the capabilities of telex, telexes quickly fell into obscurity. Compared to teletypes, the terminal screens were quiet and had no moving parts other than the keyboard, making them more reliable and enjoyable to use. Their display speed was also not limited to the mechanical action of a printhead and so they could display more information much faster than a teletype could.
Also, in the mid-1970s, personal computers like the Apple II or ZX Spectrum began to integrate input and output functionality directly into the computer itself. In the case of the Apple II, owners could use a security monitor or a standard television (with an RF modulator) as a display device, making any kind of external terminal – teletype or otherwise – unnecessary.
So the next time you sit down at your computer with a high-speed, high-resolution screen that is completely silent and exudes power, be thankful that you do not have to read iGuRu through a 10-character print machine. But on the other hand, some might find it amusing.
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