Peripheral Component Interconnect

The Peripheral Component Interconnect, or PCI Standard (in practice almost always shortened to PCI), specifies a computer bus for attaching peripheral devices to a computer motherboard.The PCI Bus is a high performance bus for interconnecting chips, expansion boards, and processor/memory subsystems.

• Wiki article on PCI

Non-Return-to-Zero Inverted

NRZI encoding is used for data transmission in the standard USB.
http://en.wikipedia.org/wiki/NRZI

EIA standards :RS232/422/485

RS 232,422,485 -quick reference

RS 232 tutorial - A very informative webpage - Recommended

Selecting and Using RS-232, RS-422, and RS-485 Serial Data Standards
An application note from Maxim semiconductors.Includes connection firures for RS232.422,485 and specifications

Dallas Semiconductor application note on RS232 - simple

RS422/485 application note