Modems: 60 years of hooking up

Modems originated as a way for teletype machines to communicate over ordinary telephone lines. In the late 1950s, AT&T developed the first commercial, mass-produced computer modem, then called a “digital subset” (shown here, circa 1958), to link SAGE computers across the United States. It communicated at 110 bits per second.

Photos: AT&T

In 1962, AT&T introduced the Bell 103 Data Phone (seen here), which set the standard for 300-baud (approximately 300-bps) full-duplex modems. Until 1984, AT&T held a monopoly on the phone system in the United States, so only AT&T could provide modems to work on its network. The monopoly stifled modem innovation until the 1968 Carterfone decision opened the market for third-party phone devices, albeit in a limited fashion.

Photos: AT&T

In the days of the AT&T phone monopoly, only AT&T had the right to connect electronic devices directly to its telephone network. Companies got around this restriction by inventing the acoustic coupler, which hooked a radio or modem to the telephone system via a cradle in which the user placed a standard phone handset. This way, the modem would be acoustically but not electronically linked, thereby avoiding any possibility of “damage” to the phone system.

Photo: Jose Guerrera

After the Carterfone decision, non-Bell companies began selling computer modems. One of the most notable for our purposes was the Hayes 80-103A, a 300-baud Bell 103A-compatible modem that happened to be the first modem created for a personal computer. Dale Heatherington (shown here) and Dennis C. Hayes designed it for S-100 bus computers of the day, such as the Altair 8800 and the IMSAI 8080.

Photos: Dale Heatherington

In 1981, D.C. Hayes Associates introduced its seminal Hayes Stack Smartmodem. The 300-baud modem was the first to integrate its own command set—one that became an industry standard. Using a series of ASCII strings sent to the modem through its RS-232 serial port, users could initialize, autodial, answer, hang up, and more. Prior to this, most users had to dial a phone number manually then hook up the modem once they heard an answer on the other end.

Photos: Hayes Microcomputer Products, Dale Heatherington

Modems for the early personal computers of the late 1970s and early 1980s were a mix of direct-connect (where the user plugged the phone line directly into the modem) and acoustic models. Some were “smart,” copying the Hayes command set; others were dumb clones of the Bell 103A standard and required manual dialing. Here we see (clockwise from upper left) the Apple Modem 300, the Commodore Vicmodem, and the Atari 830. The highest modem speed of the time was 1200 bps.

Photos: Apple, Old-computers.com, Atari

This interesting pile of PC modems from the 1980s and 1990s comes from Dave Dunfield’s personal collection. It showcases the wide range of shapes, sizes, colors, and materials used in commercial consumer modems of the day.

Photo: Dave Dunfield

From the mid-1980s onward, IBM PC clones dominated the PC market, leading to a new era of internal ISA (and later PCI) modem cards designed for PC compatibles. External serial modems held on strong, however, and around this time speedy 2400 bps modems emerged on the market. Technology pushed that limit further over the years: first to 4800 bps, and then to 9600, 14400, 28800, and beyond. Also during this era, modems gained the ability to send and receive faxes.

In the mid-1990s (when modem speeds ranged from 28.8 kbps to 33.6 kbps), internal PCI modems became such a commodity that prices plunged and vendors began to ship modems as standard components of desktop PCs and laptops. This era saw the introduction of the “Winmodem,” which offloaded some of the hardware processing to software on the computer; this innovation also made them cheaper to produce. During the same period, “voice modems” that allowed voice calls to be handled through a PC arrived.

In the late 1990s, modem manufacturers bumped up against the theoretical and legal limits of analog telephone data transfer speeds. These ceilings were about 48 kbps upstream and 56 kbps downstream with the aid of sophisticated technological trickery. Here we see a few external 56-kbps modems, an internal PCI modem, and a modem in a PC Card format for laptops.

Though dial-up modems were once standard in PCs, they are becoming scarce due to the predominance of broadband internet access. Companies still sell modems that connect through external serial ports and internal PCI slots, but one common approach is to plug in a tiny USB modem (like the ones shown here) when you need dial-up.

Photos: Apple, Zoom

Having reached the limits of analog modem technology, companies tried various new approaches to sate the public’s demand for ever-faster modem speeds. The first alternative was all-digital phone lines (ISDN), though their expensiveness limited their popularity. In the early 2000s, modems that worked over cable TV lines won a following. Phone companies also figured out how to deliver digital data more economically through ADSL lines. And then there’s wireless--another can of worms altogether.