The History of PCIe: Getting to Version 6

By Cadence

March 15, 2021

PCIe, or Peripheral Component Interconnect Express which nobody ever says, was an upgrade to the earlier PCI bus. This was developed by Intel and introduced in 1992. It replaced several older, slower buses that had been used in a somewhat ad-hoc fashion in early PCs. It was primarily a 32-bit bus, although the standard allowed for 64-bit. Most importantly, it was a parallel bus. Today, it is only of historical interest and is no longer in active use, so I won't go into any detail.

In 2004, a group of Intel engineers formed the Arapaho working group and started to develop a new standard. Eventually, other companies joined the group. The design went through several names before settling on PCI Express (PCIe). In some ways, it is a successor of PCI, in that it serves a similar function. In other ways, it is a completely different type of design. In particular, it is a serial bus, more like a network-on-a-board than the old-style parallel interface of PCI (and pretty much all other buses of that era).

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