Thunderbolt combines PCI Express (PCIe) and DisplayPort (DP) into two serial signals, and additionally provides DC power, all in one cable. It was initially marketed under the name Light Peak, and first sold as part of an end-user product on 24 February 2011. It was developed by Intel, in collaboration with Apple. Thunderbolt is the brand name of a hardware interface for the connection of external peripherals to a computer. HS1TX(P) of the source is connected to HS1RX(P) of the sink. It swaps all receive and transmit lanes e.g. This is the pinout for both sides of the connector, source side and sink side. Thunderbolt 5: 4× PCI Express 4.0, DisplayPort 2.1, USB4.Thunderbolt 4: 4× PCI Express 3.0, DisplayPort 2.0, USB4.Thunderbolt 3: 4× PCI Express 3.0, DisplayPort 1.2, USB 3.1 Gen 2.Thunderbolt 2: 4× PCI Express 2.0, DisplayPort 1.2.Thunderbolt 1: 4× PCI Express 2.0 DisplayPort 1.1a.