# USB 2 Standard-A connector > a class of legacy USB connectors that preceded USB-C (“A” indicating the host end) **Wikidata**: [Q50289351](https://www.wikidata.org/wiki/Q50289351) **Source**: https://4ort.xyz/entity/usb-2-standard-a-connector ## Summary The USB 2 Standard-A connector is a class of legacy USB connectors designed for the host end of cables, distinct from the device or "B" end. It serves as the predecessor to the modern USB-C connector, carrying only USB 1–2 data signals and power. This connector class includes both plugs and receptacles and is technically characterized by a 4-pin configuration. ## Key Facts * **Official Name:** USB 2.0 Standard-A connector. * **Function:** Acts as the host end of a cable ("A" indicates host), carrying USB 1–2 data and power. * **Successor:** Replaced by the USB-C (specifically USB 2 Type-C) connector class. * **Pin Configuration:** Features 4 leads (pins). * **Pin 1:** Vbus (Red, 5V, IC power-supply pin). * **Pin 2:** D− (White, Data minus). * **Pin 3:** D+ (Green, Data plus). * **Pin 4:** GND (Black, Ground). * **Standards Body:** Maintained by the USB Implementers Forum. * **Hierarchy:** A subclass of the USB 2 Standard connector and the USB 2 Type-A connector. * **Components:** Includes the USB 2 Standard-A plug and the USB 2 Standard-A receptacle. * **Distinctions:** Different from USB 3 Standard-A, USB 2 Standard-B, USB Micro-A, and USB Mini-A connectors. ## FAQs ### Q: What is the function of the USB 2 Standard-A connector? A: It serves as the "host" end of a legacy USB cable ("A" indicates the host), designed to carry USB 1–2 data and power. It connects host devices (like computers) to peripherals. ### Q: What is the pinout and wire color coding for this connector? A: The connector has 4 pins: Pin 1 is Vbus (Red, 5V), Pin 2 is D− (White), Pin 3 is D+ (Green), and Pin 4 is GND (Black). ### Q: Is the USB 2 Standard-A connector still current? A: No, it is considered a legacy connector class that has been replaced by USB-C connectors. ## Why It Matters The USB 2 Standard-A connector represents a critical era in the standardization of computing interfaces, serving as the ubiquitous "host" connection for nearly two decades. As the rectangular port found on almost every desktop and laptop computer, it defined how users interacted with peripherals, establishing a universal standard for both data transfer (USB 1–2) and power delivery. Its significance lies in its role as the primary entry point for the "host" side of connections, distinguishing it from the "B" or device side. While it has been superseded by the reversible USB-C standard, the USB 2 Standard-A remains one of the most recognizable and widely deployed connector classes in the history of consumer electronics. Its 4-pin design (Vbus, D-, D+, GND) became the industry baseline for low-to-medium speed data connectivity. ## Notable For * **Host Identification:** Specifically designated as the host end of the connection ("A" indicates host), distinguishing it from device-end connectors like Standard-B or Micro-A. * **Legacy Standard:** It is the definitive "legacy" connector that preceded the modern USB-C. * **4-Pin Architecture:** Notable for its specific 4-lead layout comprising Vbus, Data plus/minus, and Ground. * **Ubiquity:** As a subclass of the USB Standard-A, it is one of the most common connector classes in computing history. * **Distinct from USB 3:** It is explicitly differentiated from the later USB 3 Standard-A connector, which offered higher speeds and additional pins. ## Body ### Definition and Classification The **USB 2 Standard-A connector** is a class of legacy USB connectors defined by its role as the host end of a cable connection. Officially designated as the "USB 2.0 Standard-A connector," it belongs to the broader class of USB Standard-A connectors. It is a subclass of both the "USB 2 Standard connector" and the "USB 2 Type-A connector." The connector is strictly a legacy technology, having been replaced by the USB 2 Type-C connector class. ### Technical Specifications The connector is defined by a specific pinout of 4 leads: * **Pin 1 (Vbus):** Red wire, serving as an IC power-supply pin with a standard amount of 5 volts. * **Pin 2 (D−):** White wire, carrying the negative data signal. * **Pin 3 (D+):** Green wire, carrying the positive data signal. * **Pin 4 (GND):** Black wire, serving as the ground. ### Variants and Components The USB 2 Standard-A connector class encompasses two primary distinct components: * **USB 2 Standard-A plug:** The male connector attached to a cable. * **USB 2 Standard-A receptacle:** The female port typically embedded in the host device. ### Related Standards This connector class is distinct from several other USB form factors, including the USB 2 Standard-B connector, USB 2 Micro-A plug, USB Mini-A connector, and the higher-bandwidth USB 3 Standard-A connector. The standard is overseen by the **USB Implementers Forum**. ## References 1. [Source](https://www.usb.org/document-library/usb-31-legacy-cable-and-connector-revision-10) 2. [Source](https://www.usb.org/document-library/universal-serial-bus-31-legacy-connectors-and-cable-assemblies-compliance-document) 3. [Source](https://www.usb.org/document-library/usb-32-revision-11-june-2022) 4. [Source](https://www.usb.org/document-library/usb-type-cr-connectors-and-cable-assemblies-compliance-document-rev-21b) 5. [Source](https://www.usb.org/document-library/usb-type-cr-cable-and-connector-specification-release-24)