According to AppleInsider, Apple’s M1 chip, which the company designed especially for the Mac, implements Apple’s first custom controller for USB4 and Thunderbolt 3 and delivers the world’s first systems meeting the new USB 4 spec.
USB 4 promises a host of benefits that include faster transfer speeds, better management of video bandwidth and optional compatibility with Thunderbolt 3. According to Tom’s Hardware, it will have three main benefits over prior versions of USB:
° 40 Gbps Maximum Speed: By using two-lane cables, some devices will be able to operate at up to 40 Gbps, the same speed as Thunderbolt 3. The data is transmitted in two sets of four bidirectional lanes.
° DisplayPort Alt Mode 2.0: USB 4 will support DisplayPort 2.0 over its alternative mode. DisplayPort 2.0 can support 8K resolution at 60 Hz with HDR10 color. DisplayPort 2.0 can use up to 80 Gbps, which is double the amount available to USB data, because it sends all the data in one direction (to the monitor) and can thus use all eight data lanes at once.
° Compatible with Thunderbolt 3 devices: Some, but not necessarily all USB 4 implementations will also work with Thunderbolt 3 devices.
° Better Resource Allocation for Video, PCIe: In lieu of alternative mode where the other interface takes over the connection, USB 4 devices can use a process called “protocol tunneling” that sends DisplayPort, PCIe and USB packets at the same time while allocating bandwidth accordingly. So, if the video only needs 20% of the bandwidth to drive your 1080p monitor that’s also a hub, the other 80% will be free for transferring files from your external SSD which can operate over either USB protocol or PCIe.
By the way, USB 4 will only operate over the Type-C connector.