The full English name of USB is “Universal Serial Bus,” translated into Chinese as 通用串行总线. Products using this technology are ubiquitous in our daily lives. The original intention of its design was to replace various dedicated ports on computers with a unified interface.
1. The Birth of USB Technology
The USB standard was officially released in 1996, initially aimed at simplifying connections between computers and peripherals (such as keyboards, monitors, storage devices, etc.).
Before that, the back panels of computers commonly had parallel ports, serial ports, game ports, ADB ports, etc., each with different functions, requiring users to connect different devices with various cables—very cumbersome. The emergence of USB replaced these different types of ports with a universal interface, greatly improving ease of use and compatibility.
To unify various interfaces, several industry giants began collaborating. In 1994, seven companies—IBM, Intel, Microsoft, Compaq, DEC, NEC, and Nortel—jointly founded the USB-IF organization to promote the formulation and popularization of USB technology.
Intel contributed significantly. The team led by Intel engineer Ajay Bhatt, known as the “Father of USB,” first designed chips supporting USB. In 1995, the USB protocol entered the testing phase. In January 1996, the USB 1.0 standard was officially released (supporting 1.5 Mbps low-speed and 12 Mbps full-speed modes), marking the formal birth of USB.
In 1998, the USB 1.1 standard was officially released, supporting the connection of up to 127 external devices. That same year, Microsoft’s Windows 98 began officially supporting USB interfaces. Since then, USB technology started to spread widely.
2. Evolution of the USB Standard
Since then, the USB standard has been continuously upgraded, with increasing transfer speeds and functions:
- USB 1.x (1996–1998): USB 1.0 was released in 1996, supporting 1.5 Mbps (Low Speed) and 12 Mbps (Full Speed) modes. In 1998, it was upgraded to USB 1.1, improving hub performance and enabling more stable multi-device support. Operating systems like Windows 98 began integrating USB drivers.
- USB 2.0 (2000): Released in 2000, USB 2.0 significantly increased bandwidth, introducing the “High-Speed” mode with speeds up to 480 Mbps. It was backward-compatible with USB 1.1, leading to the phasing out of many older interfaces.
This made quick connection of external storage (such as USB flash drives), external network adapters, webcams, printers, etc., possible. Floppy disks and some fixed internal devices were replaced by USB peripherals.
- USB 3.x (2008–2017): In 2008, USB 3.0 was released, introducing a new architecture called “SuperSpeed” with speeds up to 5 Gbps. On top of the original four wires, four additional full-duplex data lines enabled simultaneous two-way data transfer, significantly improving bandwidth.
USB 3.0 also increased power output current from USB 2.0’s 500 mA to 900 mA and introduced a separate USB Power Delivery (USB-PD) standard. In 2013, USB 3.1 was released, doubling the theoretical speed to 10 Gbps (SuperSpeed+ mode), improving encoding to reduce transmission loss.
Due to naming confusion, USB 3.0 was later called USB 3.1 Gen 1, while the new 10 Gbps mode was named USB 3.1 Gen 2. In 2017, USB 3.2 introduced dual-channel technology, using two 10 Gbps channels simultaneously in a single USB-C interface, reaching up to 20 Gbps.
- USB4 (2019–present): In 2019, USB-IF released the USB4 specification, adopting a new architecture and increasing transfer rates to 40 Gbps (same as Thunderbolt 3). USB4 integrated Thunderbolt 3 technology, allowing PCIe and DisplayPort signals to transmit over a single USB-C cable, enabling dynamic bandwidth allocation for data and video.
In September 2022, USB-IF launched USB4 2.0, doubling peak speeds to 80 Gbps, further enhancing the performance of the USB-C ecosystem. Additionally, the USB standard’s power delivery capability has been gradually strengthened: the USB Power Delivery (USB-PD) specification supports up to over 100W of charging (up to 240W in newer versions), allowing devices from phones to laptops to be charged via USB.
3. Evolution of USB Connector Types
USB connector types have evolved alongside technological advancements. Common USB connectors include Standard, Mini, and Micro forms. Typical USB connector types and their features include:
- USB Type-A: A rectangular flat connector commonly used on the host side (upstream), found on desktops, TVs, and chargers. Type-A also had mini and micro variants (Mini-A, Micro-A).
- USB Type-B: A square-shaped connector used for peripherals (downstream), such as printers, scanners, and some external hard drive enclosures. Type-B also had Mini-B and Micro-B variants.
- Mini-USB: A small connector between standard and micro types, once common on digital cameras, MP3 players, etc. Most Mini-USBs were replaced by Micro-USBs.
- Micro-USB: Thinner and smaller than Mini-USB, widely used in early Android phones, tablets, Bluetooth headsets, etc. Micro-USB connectors came in types A, B, and AB, with Micro-B being the most common.
- USB Type-C (USB-C): A new-generation reversible connector standard, compact and elegant, with no distinction between A/B ends.
USB-C supports higher data rates and greater power transmission, while also supporting video and other protocols (such as DisplayPort, Thunderbolt, etc.). USB-C is now the only required connector for USB4 and the standard connection type for the latest devices (smartphones, laptops, tablets, etc.).
4. USB’s Popularization and Impact
With the evolution of standards and unification of interfaces, USB has become the default interface for consumer electronics, profoundly impacting the entire electronics industry. Nearly all computers and mobile devices today are equipped with USB ports, and legacy ports like serial, parallel, and PS/2 have gradually disappeared.
For example, peripherals like keyboards, mice, printers, scanners, and webcams all connect to computers via USB. Storage devices like USB flash drives and external hard drives also use USB for data exchange, making data transport more convenient. USB’s ease of use (plug-and-play, hot-swapping) allows users to connect various devices without manually configuring drivers.
In mobile devices, USB has fundamentally changed charging and data transmission. Previously, phones and tablets required their own unique chargers or interfaces. Now, nearly all use USB cables (earlier mostly Micro-USB, more recently USB-C) for both charging and data transfer.
The USB Power Delivery (USB-PD) protocol enables phones, tablets, laptops, and more to be fast-charged through a single USB cable. For instance, a USB-PD compatible charger can deliver over 100W to a laptop.
Additionally, emerging technologies like wireless charging and Bluetooth earphones partly rely on the expandability of the USB standard (such as USB-C’s alternate audio mode for sound output). In short, USB’s universality and convenience allow users to connect multiple devices—such as phones, earphones, and external storage—with a single cable, greatly simplifying device management in daily life and work.
5. Future Trends of USB
Looking ahead, USB technology continues to develop toward higher speeds, greater power output, and broader ecosystem integration. USB4 has already merged with Thunderbolt technology, supporting simultaneous transmission of multiple protocols for data, video, and power.
The USB4 2.0 specification introduced in 2022 further raises the maximum speed to 80 Gbps, supporting applications such as ultra-high-definition displays, external GPUs, and ultra-fast storage. The USB Power Delivery standard has been updated to version 3.1, supporting up to 240W; future versions may increase voltage and current even more to meet charging demands for laptops and even higher-power devices.
With advancements in semiconductors and system design, USB transfer speeds may continue to increase (e.g., new ultra-high-speed physical layer specifications), latency may decrease, and the ecosystem may expand into more fields such as automotive and industrial control. Overall, USB will continue to uphold its principles of universality, high speed, and ease of use, providing stronger connectivity and power delivery for the next generation of electronic devices.
In conclusion, since its inception in 1996, USB has undergone multiple upgrades from USB 1.0 to USB4. It has not only simplified interfaces and improved transfer speeds but also gradually unified charging standards. Its development has enabled our electronic devices to connect more easily and conveniently.
Looking to the future, with the release of new standards and technological advancements, USB will continue to meet growing application demands with higher bandwidth and power output, bringing more convenience to human life and remaining a technology with great development potential.
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