 For example, the 9-pin DE-9 connector is used by most IBM-compatible PCs since the IBM PC AT, and has been standardized as TIA-574.More recently, modular connectors have been used.Most common are 8P8C connectors, for which the EIA/TIA-561 standard defines a pinout, while the "Yost Serial Device Wiring Standard" invented by Dave Yost (and popularized by the Unix System Administration Handbook) is common on Unix computers and newer devices from Cisco Systems.