Editing Hayes Microcomputer Products (section)

==The Smartmodem{{anchor|Hayes Smartmodem}}==
[[File:Hayes Smartmodem 1982 (2).jpg|right|300px|thumb|The original model 300 baud Smartmodem (1981)]]
[[File:Hayes Smartmodem 1982 (5).jpg|right|300px|thumb|Essential [[interoperability]] provided via DB-25, RJ-11 and power plugs. Later modems dropped the manual volume control and introduced a second RJ-11 for pass through of the telephone line.]]
[[File:Hayes Smartmodem 1982 (6).jpg|right|300px|thumb|The Stack concept of an extruded aluminum tube open at each end, allowed for easy access of the front side DIP-switch (here left) for configuration. The complete circuit board was slid in from either end and thus easily accessible. This was also a common design copied by most modem manufacturers to come.]]
Although powerful, the internal modem was commercially impractical. Not only did it require special driver software that often meant it could only be used with a single [[terminal emulator]], but a different hardware design was needed for every [[computer bus]], including [[Apple II]], S-100, [[TRS-80]], and others. As modems became popular, users on these platforms began asking for designs as well.{{sfn|Mallett|1999}}

A solution to the cross-platform connection was to use the [[RS-232]] serial port instead of the internal data bus; modems were serial devices in the end, and most computers included an RS-232 port or some variant. The trick would be how to send commands over the same connection as the data. A few external modems already offered the ability to dial the phone by entering a phone number when the modem was first started, based on the idea that it could not be connected to a remote system when first powered up, so anything sent from the computer could (optionally) be interpreted as a command. The problem was sending a command to hang up, while the modem was already connected. There needed to be some way to indicate that the characters flowing out from the computer to the modem were not simply additional data to be sent to the far end, but commands to be acted on.

Hayes and the company's marketing manager Glenn Sirkis approached Heatherington with an outline for a new command-driven external modem. Several solutions to the command problem were studied, and in the end, Heatherington decided the only practical one was to have the modem operate in two modes. In one, ''data mode'', all data forwarded from the computer was modulated and sent over the connected telephone line as it was with any other modem. In the other, ''command mode'', data forwarded from the computer would be interpreted as commands. In this way, the modem could be instructed by the computer to perform various operations, such as hang up the phone or dial a number. The modem would normally start-up in command mode.

The problem was how to move from mode to mode. One option would be to signal this using one of the many pins in the RS-232 cable. However, while the 25-pin connector on the modem side had more than enough pins for this purpose (even some ''meant'' for this purpose), the computer side often had far fewer pins connected and controllable, if it even used a full 25-pin connector at all. In fact, there were very few pins that were guaranteed to work on all computers, mostly the data in and out, "ready" indications that said whether the modem or computer was operational, and ''sometimes'' [[RS-232 flow-control|flow-control]] pins. While it would have been possible to use some of these pins for the sort of command-switching they needed, this may not have been universally supported across all machines.

Heatherington instead came up with the idea of using a rarely seen sequence of characters for this duty. Since these characters could be sent to the modem using the same two data pins that the port would need anyway, they could be sure that such a system would work on every computer. The sequence he decided on was {{mono|+++}} (three plus signs). When this was received from the computer, the modem would switch from data to command mode. Of course, it was possible that the computer would send this sequence for other reasons, for example, the sequence is contained within the text on this page, and likely would be in any document referring to modems. In order to filter out these "accidental" sequences, Heatherington's design only switched to command mode if the sequence was led and followed by a one-second pause, the ''guard time'', in which no other data was sent. In this case it could be safely assumed that the sequence was being sent deliberately by a user, as opposed to being buried in the middle of a data stream.

With the basic idea outlined, Hayes and Sirkis gave Heatherington the go-ahead to build a prototype by adding a [[microcontroller]] to an otherwise lightly modified version of their existing 300 bit/s hardware. Sirkis was particularly interested in using the 1&nbsp;MHz [[PIC microcontrollers]], which were available for only US$1 a piece. After six months of trying to get the modem working with the PIC, Heatherington gave up and demanded they use the 8&nbsp;MHz [[Zilog Z8]] instead, a US$10 part. Sirkis acquiesced, and a working prototype was soon complete.

Hayes added a requirement of his own, that the modem be able to automatically detect what speed the computer's serial port was set to when first powered on. This was not simple unless the modem "knew" what data were initially being sent, allowing it to time the [[bit]]s and thereby guess the speed. Heatherington eventually suggested the use of a well-known character sequence for this purpose, recommending {{mono|AT}} for "attention", which is prefixed on all commands.

The new design, housed in an [[extrusion|extruded]] [[aluminum]] case sized to allow a [[Model 500 telephone|standard desktop telephone]] to rest on top, was announced in April 1981.<ref name = "CW Apr 27 1981">{{cite journal| title = Hayes Microcomputer Products, Inc. | journal = Computerworld | volume = 15 | issue = 17 | page =42 | publisher = CW Communications | date = April 27, 1981 | url = https://books.google.com/books?id=KbM9-s49yCMC&pg=RA1-PA42 | issn = 0010-4841}} The 300 baud auto-dial/auto-answer Smartmodem had a suggested retail price of $279.</ref> It was known simply as the '''Smartmodem'''. The Smartmodem was the first modem integrating complete control over the phone line, and that allowed it to be used in exactly the same fashion with any computer.

Hayes originally had big plans for the form factor, referring to it as the '''Hayes Stack''' and intending to release a range of products that could be stacked beside the computer. In the end, only two non-modem devices were added to the line.<ref name = "IW Jul 20 1981">{{cite journal| title = Hayes Smartmodem | journal = InfoWorld | volume = 3 | issue = 14 | page =9 | publisher = InfoWorld Media Group| date = July 20, 1981 | url = https://books.google.com/books?id=tT0EAAAAMBAJ&pg=PA9 | issn = 0199-6649}} "The Smartmodem is the first in a series of products Hays planes to introduce in a standard stack-mount design."</ref> The '''Hayes Stack Chronograph''', an external real-time clock and the '''Transet 1000''', a printer buffer and primitive email box.  Both of these items' sales were apparently dismal.<ref>[http://incolor.inebraska.com/bill_r/hayes_stack_chronograph.htm The Hayes Stack Chronograph]</ref>  Early advertising referred to the Smartmodem as the "Hayes Stack Smartmodem",<ref>[http://www.aresluna.org/attached/computerhistory/ads/international/hayes/pics/percon8202 Hayes Smartmodem advertisement from Personal Computing 2/82]</ref> but this naming convention was dropped a short time later.

At the time of its introduction, the modem market was fairly small, and competitors generally ignored the Smartmodem. But it was not long before hobbyists were able to combine the Smartmodem with new software to create the first real [[bulletin board system]]s (BBSes), which created significant market demand. The market grew rapidly in the mid-1980s, and as the Smartmodem was the only truly "universal" modem on the market, Hayes grew to take over much of the market. By 1982, the company was selling 140,000 modems a year, with sales of $12 million annually ({{inflation|US|12000000|1982|fmt=eq}}).{{sfn|Mallett|1999}}

Heatherington retired from what was then a large company in 1984.