Monday, 26 April 2021

Hayes Smartmodem (1981)

Introduced April 1981

The sound of modems belongs to a certain era before ubiquitous broadband. The characteristic screeching noise – a bit like a fax – joined in the rat-a-tat of dot matrix printers and the clunk clunk of mechanical disk drives. Modems had been around since the 1950s, a way of connecting computers together over the omnipresent telephone network. But initially they were very expensive and aimed at really big computer systems. As time went on, they became more affordable.. but not very usable.

By the late 1970s modems for computers had developed in two different ways – the acoustic coupler was a device where the screeching noise was fed into the telephone handset (often via a serial cable) or alternatively where it was permitted, the modem would be a card inside the computer with a telephone connection built in. But the acoustic coupler was bulky and slow, but the alternatively tended to need a modem designed specifically for every model of computer on the market – and these were only available for large systems and not the booming microcomputer market. There had to be a better way.

What was needed was a modem that could work with just about anything. That was the Hayes Smartmodem.

Hayes Smartmodem
Hayes Smartmodem


The “Smart” in Smartmodem wasn’t just marketing speak. It took advantage of the fact that almost every microcomputer system on the market had a serial port fitted, or one available as an optional extra. By using a serial port, all you needed to connect the Smartmodem to your micro was the appropriate cable, which if you couldn’t buy you might be able to make yourself.

But the implementation of serial ports varied from computer to computer, the Smartmodem needed to know (for example) when to hang up the connection. More sophisticated computers used pins to indicate when the connection was up or down, but cheaper ones didn’t. The serial port could also be running at a variety of speeds, so matching the port with the modem could be tricky on some devices.

Hayes designed a series of commands to control the modem, all beginning with “AT” for “attention”. But because all the commands started with the same two latters, the modem would attempt to use this to automatically match the baud rate of the computer with the modem. This made setting up the Smartmodem much simpler, but there was a more tricky problem… how could you tell the modem to hang up if you had a basic serial port that didn’t have the right wires to signal that to the modem?

To achieve this, the Smartmodem would look for a sequence “+++” followed by a once-second pause. This would break out of the communications sequence and make the modem ready to receive a command. If that command was ATH then the modem would hang up. It was an elegant solution, the pause minimised the possibility of it happening by accident. When competitors tried to copy the functionality of the Smartmodem, this was often implemented badly (in part because Hayes had patented it and demanded a fee). This meant that on some non-Hayes modems could hang up completely at random if they were sent the +++ sequence accidentally.

In these pre-internet days, modems would be use to connect computer directly to another computer, or perhaps to a BBS (bulletin board system) or if you were one of a small number of privileged people, they could act as a gateway to what was to become the internet.

The original Hayes Smartmodem was a 300 baud unit, but as technology improved the Hayes modems became faster. However, competition was also becoming fierce and although Hayes products were expensive, they were also very reliable and they carved themselves a healthy share of the market.

All good things come to an end though, and in the 1990s Hayes bet the barn on ISDN products, a market that never materialised. Competitors such as USRobotics were taking the analogue modem market. By the mid-1990s Hayes were in serious trouble. Bankruptcy and mergers led to them being subsumed into rivals Zoom Telephonics, where the brand eventually vanished. However, the Hayes website is still available although it was last updated in 2013.

Surprisingly, analogue modems are not quite a dead technology but their heyday has certainly passed. However, Hayes certainly made it easier to connecting disparate computer systems together and in part that drove the uptake of the internet in the 1990s.

Image credit:
Michael Pereckas via Flickr - CC BY-SA 2.0


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