Applications undreamed of a few years ago -- like digital audio and computer telephony integration -- have pushed PC peripheral port capacity to the limit. Answering the call for more and easier-to-use peripherals, last year a group of PC and telephone industry leaders developed the Universal Serial Bus (USB) specification. With USB, users will never need to open their PC to plug in peripherals or their associated cards; instead, adding peripheral devices is as easy as plugging in a table lamp. Offered as an open, royalty-free specification, the plug-and-play Universal Serial Bus reinvents the peripheral connection, and makes catching the next wave of sophisticated PC applications simple and inviting enough for even the novice user.

Already, based on early system and peripheral OEM acceptance, the Universal Serial Bus is poised to become a key feature of PCs introduced this year. The hardware, software and design tools for making USB-compliant PCs and peripherals are ready. Soon, with USB-compliant PCs creating the market opportunity and development and prototype support at hand, peripheral makers and software vendors will be able to introduce new products touting unprecedented ease of installation and functionality. Examples of devices that will connect to the Universal Serial Bus include telephones or telephone network, modem, printer, microphone, digital speakers, writing stylus, joystick, mouse, scanner, game pad and digital camera.

Serial Thriller: True Plug-and-Play Operation
Today, each peripheral device needs its own port, usually gained through one of a few add-in slots available on the PC motherboard. To install all but the most fundamental peripherals -- keyboard, monitor, printer and modem -- the user must open the case and insert a board. Often, switches must be set, jumper wires configured or the different physical connectors, such as serial or parallel, matched -- steps that frequently discourage the average user from bothering with new peripherals at all. And once those slots are filled, the door is closed to adding more peripherals.

In contrast, simplicity and ease stand at the center of the Universal Serial Bus. Drawing its intelligence from the host PC, the Universal Serial Bus detects when devices are added or removed, which -- unlike with conventional add-in slots -- can be done with the power on and without having to re-boot the system. Moreover, offering true plug-and-play operation, the Universal Serial Bus automatically determines what host resources, including driver software and bus bandwidth, each peripheral needs and makes those resources available without user intervention. Lastly, the Universal Serial Bus specification also defines a standardized connector and socket which all peripherals can use, thus eliminating the existing mixture of connector types.

With USB, one peripheral device, such as the keyboard or monitor, plugs directly into the PC. Other peripherals simply connect into either an expansion hub built into the keyboard or monitor, or into a stand-alone USB box. Such expansion hubs provide additional connection sockets and can be connected into a tiered tree arrangement. Each peripheral can extend up to five meters from each other or from the expansion hub. In all, USB can connect up to 127 different devices to a single PC and carries +5-volt power which eliminates the bulky AC power pack that many peripherals currently require. Plus, at cost equivalent to today's connector technologies, USB's 12-Mbit/sec. data rate offers ample throughput for nearly all the highest bandwidth peripheral devices for which higher performance yet inherently higher cost technologies exist.

Shipping Chips
It is the availability of silicon and development tools that will make 1996 the year that USB establishes itself as the ubiquitous PC peripheral connection. Specifically, Intel is now shipping its PCI chipsets for the Pentium® processor: the 430HX and 430VX, that implement the USB interface.

Of the chip-level products, the 82930A is the first USB-compliant peripheral controller chip, and one of a family of such chips being planned. An 8-bit microcontroller built on the popular MCS® 251 microcontroller core, the 82930A is served by the same high-level programming and development tools as the MCS 51 and MCS 251 microcontrollers. For the many designers already familiar with these architectures, product development using the 82930 USB controller will be quick and easy.

Of course, the market for USB-compliant peripherals would not develop without PCs equipped to support them. For that reason, Intel has added two new members to its 430 family of fourth-generation PCI chipsets; products at the core of nearly all Pentium processor-based PCs. Comprised of the 430HX for reliable, high-performance business PCs and the 430VX for multimedia-ready, value-priced home PCs, the new chips are the first to offer USB-compliant capability.

Not limiting its efforts to silicon, Intel is offering a complete evaluation tool kit for the Peripheral Developer and a Universal Host Controller Interface (UHCI) design guide (pdf 519,067 bytes). The USB 930 Evaluation Kit includes programming tools for writing host software (SSTD), an evaluation board and software tools for developing the peripheral itself. Among the peripheral software tools are ApBuilder, an on-line tutorial for the peripheral controller; compiler and code examples; and documentation. ApBuilder is available through the internet. To order an evaluation kit (order number: USB930EVALKIT) or for access to the SSTD website, please contact your local Intel sales office. Additionally, the UHCI design guide, which describes the register-level interface within Intel's USB host controller, as well as the software data structure needed to control the bus, is available. Using the guide, component suppliers can bring host products to market, assured they will fully meet the Universal Serial Bus specification.

Intel's silicon and development products comprise a complete, end-to-end solution that allows OEMs to bring USB-compliant PCs and easy-to-install, USB-compliant peripherals to end users quickly, elevating the coming generation of PCs to new levels of versatility and performance.

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