A boy sits in front of his computer. Through the telephone line, he connects to his high school computer and makes some changes to please his girlfriend, who is with him at the time. All hacker. What strikes many of us is that, apart from the fact that the computer is old, to connect to the computer at his institute, he first types a few numbers on the phone and then connect the telephone terminal to a device. That device is called acoustic coupler and this is how they communicated first home computers at a time when the internet was beginning to take its first steps. The scene, by the way, is from the movie WarGames (War Games, 1983). The leading boy is played by a very young Matthew Broderick. And his partner, on the scene, is the actress Ally Sheedy.
If you want to know what will end up happening in that movie, I recommend you watch it. The story is good somewhat valid today and, in addition, you will be able to delight yourself with the eighties technology that is shown in it. A fun way to travel back in time. But we are going to focus on that device they use to connect computers to each other. The acoustic coupler. In English acoustic coupler. Its name gives us a clue as to what it is for. coupler cos attach the headset and microphone from the phone to that device. Come on, the part that you take to your ear and mouth respectively to make a call. For its part, the acoustic thing comes because the device communicates your computer with another employing acousticsthat is, sounds.
It is clear that this for many sounds like prehistory. To begin with, today we connect to the internet mainly from our mobile phones. The statistics speak of 57% of web traffic via smartphones. In any case, to connect to the network of networks via a computer, tablet or other device, we use what we know as a router or router. But before the router was the modem. And before the modem, or rather in parallel, it was the acoustic coupler. Let’s see the reason for its invention and what this strange apparatus of the last century consisted of.
Those wonderful years
I mentioned as an example the tape WarGames 1983 because it clearly shows the operation of an acoustic coupler. Specifically, it is the Novation CAT 300. Home Novation was among the first to make modems for the home market in the 1970s and 1980s. Closer to the latter than the former. The Apple II, for example, could “connect to the Internet” with an internal modem made by Apple. Novation. Yes, it was sold separately.
Acoustic couplers were practically the first modems, especially at home and in the United States. We will explain why later. They were used to connect computers to each other through the telephone line, the now classic copper pair. You typed in the telephone number that corresponded to the computer in question, you placed the microphone and headset in their corresponding slots and the coupler communicated with the other coupler through sounds. Those sounds were translated into electrical signals that the computer could understand. A relatively simple method of sending information and that was used to access a bank or your company’s computer.
However, the speeds were around 300 baud. To get an idea, the fastest modems that came in the 90s, before the advent of ADSL, reached theoretical speeds of 33 kilobauds (33,000 bauds) and later 56 kilobauds (56,000 bauds). If the baud unit of measurement doesn’t sound familiar to you, don’t worry. As ADSL was imposed as a technology to access the Internet, baud gave way to bit. Moreover, many times they were confused with each other despite not being exactly the same.
By the way, I put quotation marks before about “connecting to the internet”. The reason is that in the 70s and 80s, what we now call the Internet practically did not exist. There were services independent of each other such as newsgroups, databases or shared lists. Scattered information that, in some cases, was paid for and had limited access. In any case, there was no easy way to connect to the internet. actually you could communicate with specific computers, which could be from individuals, institutions, companies or that offered a certain service. If you lived in the United States, at this time it was common to brag about having communicated with the computer of Bill Gates, Steve Jobs or the famous person on duty.
The rationale for the acoustic coupler
Although the days of fixed telephony are numbered, fixed telephones still proliferate in many homes. Either in its classic cable mode or with wireless terminals connected to a fixed base. Be that as it may, to connect said terminal to the telephone network we use a cable known as RJ11 or RJ-11. It’s more. Before this cable was connected directly to the copper network. Today those networks are being dismantled, so it is usual that your landline phone is connected to the router.
But obviously, the RJ11 standard was not always there. Previously, the phone connected to the network directly using a direct cable. Come on, there was no easy way change phone terminal. Hence, since there was no RJ11 input, there was no way to connect a cable or adapter. The modems that came out in the 90s could take advantage of the RJ11 standard and connect the modem to the telephone line with an RJ11 cable.
But in the United States, it was not until the late 1980s that this was possible. Until then, the only way to connect the computer to the telephone line was with a device that converts data into sounds and vice versa. It’s more. In the United States another detail is added. Until 1984, the company Bell It had practically a monopoly on the telephone network. And as such, it applied rules such as that the client’s telephone terminal should be the one marked by the company.
In Spain and other countries the situation was not so dramatic. But mainly because the connections between computers were not so frequent. As we saw in a previous article, it was not until 1995 that Internet access from homes became popular. In the 80s and 90s, you could only access it from universities or companies that had the necessary budget. And at first, accessing the internet simply means connect to databases that were updated frequently. But light years away from what we know today. However, those who connected to the Internet at this time probably also used acoustic couplers because they were most popular mods then.
The inventor of the acoustic coupler
The father of the acoustic coupler is the American Robert Weitbrecht. Interestingly, he passed away in 1983, the year it was released. WarGames, the film with which we started this article. Born in 1920, he was physicist and engineer. He first worked at the University of California Radiation Laboratory. He later worked for the US Army at the Naval Air Missile Test Center. And eventually he created his own company, Weitbrecht Communications. It was then that he had contact with James Marsters. They were both deaf. And both collaborated to create what we know as acoustic coupler.
But we are talking about 1964. This first acoustic coupler allowed connect two phones to make a call which was converted into written messages. The sound of it, which was transmitted through the copper telephone line, was translated through the coupler. But instead of data appearing on a computer screen, it was printed out on a sort of printing device somewhere between a modern fax or printer. The result, two deaf people could communicate using phone calls.
Thus, this first acoustic coupler already did what I explained before. Convert sound into data, in the form of electrical signals. But instead of sending those signals to a computer, they were converted into printed text. It is not surprising that acoustic couplers emerged focused on directly communicating machines. In 1966, without going any further, John van Green makes connection between 8-bit computers possible. And as of 1973, models prepared to access the internet of that time and connect computers together through the telephone network. Thus until the first half of the 90s, when the use of these devices was replaced by modems and routers.
The Acoustic Coupler for iPhone
Throughout this article I have been saying that the acoustic coupler is a technology of the past. And so it is. But there is always someone who decides save, collect and even restore old pieces to give them a use, even if it is anecdotal. And with acoustic couplers it happens like this. Browsing through thrift stores and collector sites, it’s relatively easy to come across several couplers in relatively fair condition.
Beyond collecting, acoustic couplers still appear in curio articles. In Reddita user two years ago fretted with an acoustic coupler and managed to access a BBS or Bulletin Board System, the ancestors of the forums. In the experiment he used an iPhone and various adapters. More than anything because the input of the coupler is a port like the one on old printers and the port on an iPhone is Lightning.
Another anecdote related to acoustic couplers has to do with a coupler created to be compatible with an iPhone. An evolution of the previous example where the docker is created practically from scratch. employing Arduinoa portal member Hackaday decided to build an acoustic coupler for his son, who had to travel to China. To avoid censorship on the Chinese internet, instead of using a VPN he tried a more traditional method. this coupler was fabricated with a wooden casing that had a perfect slot to place an iPhone. Thus, the microphone and headphone of the Apple device fit with the coupler and the coupler could do its job.