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Universal Serial Bus (USB)
“By the mid-1990s, the back of most computers looked like a rat’s nest of cables and connectors. There was a serial port for connecting to a telephone modem, PS/2 connectors to connect to a keyboard and mouse, a 25-pin parallel cable for the printers, and of course the power and video cables as well.
The Universal Serial Bus (USB) was envisioned to end the madness, providing a single standard for transmitting data and power over cables. It was designed by a group of seven companies: Compaq®, DEC, IBM, Intel, Microsoft, NEC, and Nortel®. The standard was first published beyond the group of creators in January 1996. Its inventors expected the computer industry to make a slow, gradual transition from the era of legacy ports, presumably with several generations of computers that offered both legacy and USB ports.
But USB made its consumer debut with the introduction of the Apple iMac®. Apple, whose Macintosh computers had used the proprietary Apple Desktop Bus (ADB) since 1986, was eager to adopt a new technology that would make it easy for its users to purchase commodity keyboards, mice, and other specialty devices. So Apple jumped in headfirst: when the iMac went on sale in August 1998, it had USB but no legacy ports at all. Legacy devices and cables on the PC side, however, would take a decade to phase out completely.
By 2010, USB had replaced not just all legacy data connectors, but power as well: except for Apple’s iPhone, virtually all cell phones and many other low-power devices had adopted USB mini microconnectors for charging. Equally ubiquitous were USB “thumb” drives that packed gigabytes of portable, permanent storage.
A problem with USB is that its cables are not symmetrical: USB cables have an A-side that plugs into computers and a B-side the plugs into the “downstream” device (typically a printer or a phone). The plugs themselves can be plugged in only one way. USB Type-C solves both problems, with connectors that can be flipped and reversible cables. Type-C can also carry up to 100 watts of power. In 2015, Apple introduced a MacBook with a single USB Type-C connector; later Apple laptops featured two or four Type-C connectors.”
SEE ALSO Recommended Standard 232 (1960)
The Universal Serial Bus provides a single standard for transmitting data and power over cables.