The Free On-line Dictionary of Computing (30 December 2018):

Peripheral Component Interconnect
PCI
PCI bus

    (PCI) A standard for connecting peripherals to a
   personal computer, designed by Intel and released around
   Autumn 1993.  PCI is supported by most major manufacturers
   including Apple Computer.  It is technically far superior to
   VESA's local bus.  It runs at 20 - 33 MHz and carries 32
   bits at a time over a 124-pin connector or 64 bits over a
   188-pin connector.  An address is sent in one cycle followed
   by one word of data (or several in burst mode).

   PCI is used in systems based on Pentium, Pentium Pro, AMD
   5x86, AMD K5 and AMD K6 processors, in some DEC Alpha
   and PowerPC systems, and probably Cyrix 586 and Cyrix
   686 systems.  However, it is processor independent and so can
   work with other processor architectures as well.

   Technically, PCI is not a bus but a bridge or mezzanine.
   It includes buffers to decouple the CPU from relatively slow
   peripherals and allow them to operate asynchronously.

   (1997-12-07)