Percom

Percom
Name	Percom
Type	Protocol/Platform
Introduced	c. 1980s
Developer	Various companies and standards bodies
Related	IEEE, USB, RS-232, Apple Computer, Intel, Compaq, Microsoft

Percom is a term applied to a family of serial communication protocols and peripheral interfaces that emerged alongside microcomputer expansion in the late twentieth century. It bridged early serial standards and later universal interfaces by providing layered specifications adopted by hardware vendors, chipset manufacturers, and software developers. Percom variants influenced interoperability among companies and institutions involved in personal computing, telecommunications, and embedded systems.

Definition and Etymology

Percom denotes a set of protocols and interface conventions for peripheral communication promulgated by companies and consortia active during the microcomputer era. The name derives from a contraction of "peripheral communication," reflecting aims similar to those of IEEE standards and interface efforts such as RS-232 and USB. Early documentation and marketing used the Percom label to signal compatibility with microprocessors from Intel and Motorola, microcomputers by Apple Computer and Compaq, and operating environments like MS-DOS and CP/M.

History and Development

Percom development unfolded amid competing approaches led by semiconductor firms, peripheral manufacturers, and computing companies. Initial efforts paralleled work by Bell Labs researchers and standards activity within ANSI and ITU-T on serial signaling. As microcomputers proliferated, firms such as Intel, Motorola, Zilog, and manufacturers represented by VIA Technologies and National Semiconductor implemented Percom-compatible UARTs and controller chips. The rise of personal computing companies including IBM, Apple Computer, Compaq, and Tandy Corporation created demand for interoperable peripherals and spurred adoption in printer, modem, and terminal markets dominated by vendors like Hewlett-Packard, Epson, Roland, and USRobotics.

Standards committees and trade associations, sometimes overlapping with IEEE working groups, documented pinouts, signal levels, and handshaking behaviors to align Percom with existing conventions such as RS-232 and later to interwork with packet-oriented frameworks developed by IETF and ITU. Semiconductor implementations embedded Percom functionality into controllers used by OEMs including Dell, Gateway, Inc., and Acer, and influenced firmware and driver stacks in Microsoft Windows and Unix variants maintained by organizations such as The Open Group.

Applications and Use Cases

Percom found use across diverse peripherals and systems where serial or low-pin-count interfaces were advantageous. Prominent applications included connections between microcomputers and printers produced by Epson and Hewlett-Packard, external modems from USRobotics and Zoom Telephonics, and terminals manufactured by DEC and Wyse Technology. Embedded applications appeared in consumer electronics by Sony and Panasonic, telecommunications equipment by Nortel and Ericsson, and industrial controllers from Siemens and Schneider Electric.

Developers integrated Percom in point-of-sale systems built by NCR Corporation and Diebold Nixdorf, instrumentation from Keysight Technologies and Fluke Corporation, and automotive diagnostic tools produced by Bosch and Delphi Automotive. Software support came from operating systems and driver ecosystems including MS-DOS, Microsoft Windows, FreeBSD, NetBSD, Linux Kernel, and embedded RTOS providers like Wind River Systems and QNX Software Systems.

Technical Characteristics and Standards

Technically, Percom specifications covered electrical signaling, connector pinouts, flow control, framing, and initialization sequences. Electrical characteristics drew on voltage and timing practices found in RS-232 and transistor-transistor logic conventions used by Intel microcontrollers and Motorola CPU families. Connector types often matched those standardized by industry participants such as DB-9 and DB-25 conventions used in serial communications.

Flow control mechanisms aligned with software implementations in Kermit and terminal control protocols like VT100 emulation. Error detection and framing recommendations echoed practices from data link protocols standardized by IETF and framing approaches used in X.25 and HDLC. Phased updates to Percom addressed higher-speed transport to interoperate with bus standards like PCI and peripheral interconnects exemplified by USB and FireWire developed by companies such as Intel and Apple Computer. Chipset vendors including Texas Instruments and AMD produced integrated controllers implementing Percom features, and test suites were adopted by certification labs and agencies like UL.

Market and Industry Impact

Percom's influence is perceptible in how vendors negotiated interoperability and in the evolution of peripheral ecosystems. Its conventions smoothed integration for OEMs like IBM, Apple Computer, and Compaq while enabling peripheral businesses such as Epson, Hewlett-Packard, and USRobotics to target broad markets. Standards alignment with bodies like IEEE and practical uptake by semiconductor firms including Intel, Motorola, Texas Instruments, and National Semiconductor reduced fragmentation that might otherwise have hindered the growth fueled by Microsoft Windows platforms and server ecosystems from Sun Microsystems and HP Enterprise.

Market consolidation in the 1990s and 2000s, including mergers involving Hewlett-Packard, Compaq, Dell, and Gateway, Inc., together with the emergence of universal interfaces such as USB and PCI Express, shifted industry focus away from legacy Percom-specific implementations. Nonetheless, Percom concepts persist in embedded systems, legacy industrial installations by Siemens and Schneider Electric, and interoperability practices taught by standards organizations like ISO and IEC.

Category:Computer interfaces