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How to Identify USB Types and Versions by Appearances?

Author: Apogeeweb Date: 1 Jun 2021  352

usb symbols labeled


In modern daily life, you can always see one or more USB ports on virtually desktop computers, laptops, TVs, game system devices, cars, media players, and other devices, etc. USB devices are very common, in addition, we probably know what it used for. However, fewer people know the full name of USB and what the real differences between USB standards and USB types.

USB Ports, Cables, Types, & Connectors



Ⅰ USB Ports and Standards

1.1 USB: What Is It?

1.2 USB Bus Signal

1.3 USB High Speed, Low Speed Identification

1.4 USB Port Colors Meaning

Ⅱ Is USB-C and Type C the Same?

Ⅲ Labels Behind USB Ports

Ⅳ Frequently Asked Questions about USB Types and USB Versions

Ⅰ USB Ports and Standards

1.1 USB: What Is It?

usb devices

USB is a universal serial bus standard and a technical specification for input and output interfaces. It is widely used in information transformation products such as personal computers and mobile devices. The USB interface has hot-swappable, plug-and-play functions, and can be connected to a variety of external devices, such as a mouse and keyboard, etc. Our mobile phone charging uses the USB connector. These USB devices give us great convenience. USB chargers, USB connectors, and USB cables, are all USB the same? What is USB 2.0 and USB 3.0? What is low speed, full speed, and high speed? What are Type-A, Type-B, and Type-C? Here you will get a full answer.

  • Versions of USB

usb versions

The USB 1.0/2.0/3.0 we often say refers to the technical specifications. The biggest difference among them is speed, that is, they indicate the speed of USB transfer files. The maximum transmission bandwidth of USB 3.0 is up to 5.0Gbps (640MB/s). Now many high-speed U disks or mobile hard drives use USB 3.0 or USB 3.1. USB also includes the old USB 1.1 standard and  USB 2.0 standard. The traditional maximum transfer rate of USB 1.1 is 12Mbps. Generally, manufacturers call its products that comply with the USB 1.1 standard as "full-speed USB." When the high-speed USB 2.0 was first introduced, the highest transmission rate was only 240Mbps. Later, the USB Promoter Group increased the rate to 480Mbps in October 1999, which is 40 times faster than the traditional USB 1.1. USB 2.0 is backward compatible with USB 1.1. Of course, USB 1.1 devices are also "upward compatible" with USB 2.0, however, they cannot realize the transmission capability of USB 2.0 and automatically transmit at low speed. The maximum length of the USB 2.0 cable is 5 meters, but if five USB adapters are used, the maximum length can be up to 30 meters.
Although you'll still be able to connect old-school devices with USB Type-A or USB Type-B connectors, but now you have more choices, that is USB4. USB4 is a USB system specified in the USB4 specification which was released in version 1.0 on 29 August 2019 by USB Implementers Forum. It leverages the Thunderbolt 3 protocol to deliver speeds up to twice as fast as the USB version it replaces. The USB4 architecture defines a method to dynamically share a single high-speed link with multiple end device types to best serve the transfer of data by type and application.


  • USB-A, USB-B, and USB-C Port Types

usb types

Type-A/B/C determines the appearance of the USB ports. For example, the mouse, keyboard, USB flash drive and other interfaces we use are generally Type-A, which is also the most widely used interface. Type-B is more common in printers, monitors and other devices. In the past, Micro USB and Mini USB commonly used in mobile phones were portable versions of USB 2.0. The appearance of Type-C is very recognizable, slimmer. Its biggest feature is flippability, that is, USB-C connector has no up or down orientation, so you never have to flip it over to plug it in.
1) Type-A: Standard USB Port

usb type a

Type-A is the most common types of USB ports on computers. It has a notable feature: direction requirements. The connector (male port) must be inserted into the interface (female port) from a certain direction, in addition, because the appearance of the two sides of the USB male port is very close, this insertion process often makes mistakes.
2) Type-B: Commonly used in printer equipment
Type-B is the most common and popular data interface type on printers and displays, and some displays will also use it.
3) Type Micro-B: USB standard for mobile devices

Micro USB and Mini USB

Currently, most Android phones use the Micro USB interface (USB Micro-B), which is still widely used in various mobile portable devices.
4) Type-C: It will become mainstream
Although Type-C has just appeared, it is foreseeable that as the USB Type-C technology matures, various notebooks, tablets and even smart phones in the future will begin to use the USB Type-C interface.

1.2 USB Bus Signal

USB uses differential signal to work, two data lines D+ and D-
Differential signal 1: D+> VOH(208V) and D- <VOL(0.3V)
Differential signal 0: D-> VOH and D+ <VOL
Reset signal (Reset): D+ and D- <VOL for >= 10ms
IDLE state: J state
Resume signal (Resume): K state
SOP: Switch from IDLE state to K state
EOP: SE0 signal lasting for 2 bit time, followed by J state for 1 bit time
SYNC: 3 repeated KJ state switching, followed by K state for 2 bit time

usb bus signal

1.3 USB High Speed, Low Speed Identification

usb speed

The 1.5K pull-up allows the host to detect the device attachment and its supported speed.
High-speed device is detected first as full-speed device then high-speed capability is detected through bus handshake mechanism called "chrip sequence".

1.4 USB Port Colors Meaning

usb port colors


USB Connector

USB Speed Standard



USB-A or USB-B  Micro USB-A

USB 1.0 or USB 1.1



USB-A or USB-B Micro USB-B

USB 2.0 Hi-Speed




USB 3.0 Super Speed



Sleep-and-Charge USB-A

USB 3.1 Gen 2 

USB 3.2

Usually denotes an "always on" port


Sleep-and-Charge USB-A

USB 2.0 or USB 3.0

Higher power or "always on" port

Ⅱ Is USB-C and Type C the Same?

The Type-C is the same as the USB C, because the USB C is also called USB Type-C. However, there are slight differences between them. Let’s look at the following facts.
Features of USB-C Connector:
1. Ultra-thin
The old USB port size is 14mm * 6.5mm, while the USB-C is only 8.4mm * 2.6mm.
2. No Orientation
Like the Lightning, there will be no problem regardless of whether it is plugged in or reversed. It claims to be able to up to 10,000 times of repeated plugging and unplugging.

Apple Lightning

3. Fast Transfer Rate
The maximum transfer rate of the USB-C port is 10Gb per second, which is much faster than USB 3.0.
4. Two-way Transmission
Unlike the old USB port, the power can only be transmitted in one direction. The USB-C port is bidirectional, which means that it can have two transmission power modes. Therefore, users can not only use laptops to charge mobile devices, but also use other devices or mobile power sources to charge laptops.
5. Strong Power Supply Capability
The standard specification cable equipped with Type-C connector can pass 3A current, and it also has a super USB power supply capacity, which can up to 100W of power.
6. Backward Compatibility
USB-C can be compatible with the old USB standard, but users need to purchase an additional adapter to complete the compatibility.
USB-C refers to the Type C port that uses the USB 3.1 standard, but it should be noted that USB-C is not equal to Type C. Because there are many

computer usb c port

Type C devices that can only reach USB 2.0 or USB 3.0 transfer rate.
With the improvement of technology, Type-C also supports the USB3.1 standard. Because the voltage and current increase, the coding consumption is reduced, from 20% of USB 3.0 to 3%. In other words, users can quickly transfer data and video through Type-C, or charge faster. The standard also allows users to charge other devices with their mobile phones. As for the display, when using Type-C for data transmission, there is no need to use another power cord to power the display, which solves the problem of messy desktop cables. Even the relatively high-end HDMI and DP ports cannot do it.
The USB-C connector can be expanded into three: power supply/ USB transmission/ VGA or HDMI, which is the next-generation mainstream USB interface. The type-c cable is also of great help to the arrival of the 5G. Because the port of it becomes smaller, the flattening of electronic products is promoted. And in the transmission of audio and video, the tc data line has faster speed. At present, well-known technology manufacturers such as Sony and Apple have widely used type-c cables on their electrical devices because they can support multiple formats and reduce the limitations of USB. In short, the arrival of the 5G actually wants everyone to experience faster bandwidth, so the corresponding supporting facilities should also keep up. The type-c cable is undoubtedly one of them.


Ⅲ Labels Behind USB Ports

usb labels

"+" sign - It represents the USB interface with high current output capability. The ordinary USB interface provides a maximum current of 500mA, but it may not be able to drive when encountering "high energy consumption" devices such as mobile hard disks and USB optical drives. Therefore, when it appeared, the output current of this interface can reach 1000mA (1A), which greatly enhances the device drive capability.
"SS" - It is actually a symbol of USB 3.0. If the USB port has “SS” (or “SuperSpeed”) on its label, it’s a USB 3.0 port. If it’s“SS 10”, it’s a USB 3.1 port.
"Lightning Logo" -It generally appears on notebooks, and the USB port with it has a power-off charging function. That is, it can use its own battery or an external power supply to charge the mobile device when it is turned off. The lightning mark with an arrow indicates the Thunderbolt 3: two-way charging and two-way data transmission. Thunderbolt 3 supports for up to 40Gbps of throughput, alongside reduced power consumption and the ability to move as much as 100 watts of power over the interface. And it also means that a single cable is all you need to push power and transfer a large amount of information (up to and including video data for two 60Hz 4K displays) to and from even a complex device like a computer, something many laptop manufacturers have been quick to take advantage of.


Ⅳ Frequently Asked Questions about USB Types and USB Versions

1. What are the different types of USB ports?

Types of USB Ports and Connectors
USB-B Mini
USB-B Micro


2. How can I tell the difference between USB 2.0 and 3.0 ports?

You can generally tell the difference between USB 1.0, 2.0, and 3.0 by color alone. While the size and shape may be identical, the key is to look at the color of the plastic inside the device. The USB 1.0 features a white plastic color, while USB 2.0 is black, and the USB 3.0 is blue.


3. What is the difference between USB Type A and C?

The USB-A has a much larger physical connector than the Type C, Type C is around the same size as a micro-USB connector. ... The beauty of Type C is that it can be inserted any way up as the connector pins are the same on either side.


4. Are USB 2.0 and 3.0 ports the same?

The A connectors still work properly so any 2.0 device with a 2.0 cable can be used with 3.0 ports or hubs. To sum up: USB 3.0 devices require 3.0 cables. ... USB 2.0 cables can be used with 3.0 ports but the transfer rate will fall back to 2.0.


5. Why is my USB 3.0 port not working?

Update to the Latest BIOS, or Check USB 3.0 is Enabled in BIOS. In many cases, your motherboard will be responsible for software issues related to your USB 3.0 ports or any other ports on the motherboard. For this reason, updating to the latest BIOS may fix things.

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pinglun 1 comment

    • pingluntus
    • Peyton on 2021/6/18 11:46:14

    I see quite a few motherboard reviews online these days where the reviewer criticises the lack of USB ports on boards that have 4 to 6! I find this quite bizarre as I use a maximum of 4 USB devices and even if there were only 4 ports on my board and I got another USB device I could just use a hub. So, how many USB ports do you want?

      • pingluntu
      • author on 2021/6/19 16:09:00


      I use 8 + 2 on the case from my motherboard, but I do have 3 extra controllers, a USB WiFi adapter, and USB3 multi card reader plugged in all the time. I could manage with less.
      Even though I have USB-C gadgets (phone etc), I don't see a need for it on my PC. USB-A to C works fine.

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