USB, to be precise, USB TYPE-A, is undoubtedly the most popular and popular standard interface.

Even if USB TYPE-C has a tendency to replace it, in a short period of time, when a large number of external devices cannot fully transition to TYPE-C, TYPE-A USB on computers or other digital devices will still be the most mainstream interface .

However, when using a computer, everyone may encounter a problem, that is, when plugging in the USB cable to the device, it often fails to plug it in for many times. Finally, you need to confirm the forward and reverse directions before you can plug it in.

In contrast, the fool-plug TYPE-C USB is much more convenient. So, have you ever thought about a question, why did TYPE-A USB not adopt the plug-in method at the beginning of the design?

Reason 1: Design Thinking

In fact, various standard interfaces "from ancient times to the present" have generally adopted the "incompatible physical design" method in foolproof design.

At the beginning of the interface design, the normal thinking is not to consider the positive and negative insertion, but consider "the reverse insertion will definitely not be inserted, so it will not deliberately design the positive and negative insertion style."

For example, various standard interfaces on computers, such as network cable ports, DP ports, HDMI ports, and older ones such as VGA port, PS2 port, etc., all adopt incompatible physical design methods.

For example, the protrusions on the crystal head, the special-shaped design of the HDMI upper and lower width, the VGA pin position misalignment, the PS2 interface/DP interface notch design, etc., are all incompatible physical foolproof design solutions.

In fact, TYPE-A USB is also an incompatible physical fool-proof design. It uses a different thickness of the fool-proof design to help users determine the correct insertion position.

But compared with the more obvious fool-proof design mentioned above, the failure of TYPE-A USB is that its fool-proof design is not obvious, and it uses a regular rectangular design.

Its biggest failure is not that it can only be inserted in one direction, but that it cannot be realized by observing the appearance and touch, and then simply and quickly distinguishing the positive and negative.

Therefore, when plugging in the USB cable, it is often blind plugged many times and cannot be plugged in. It is still necessary to check the forward and reverse directions to insert it smoothly.

Reason 2: The law of technological change

In addition to the design thinking level, there is another important reason why TYPE-A USB did not consider the positive and negative insertion at the beginning of the design is the interface technology.

In fact, all technological developments are continuous, which also means that in terms of technological progress or breakthroughs, innovation is easier than creation.

In the initial stage of technology development, the first thing to do is to design a prototype. As for optimizing performance, structure, appearance, and even user experience, it is often something that will be done after the subsequent technology matures. The most obvious example at this stage is the field of intelligent robots.

Speaking back to the USB interface. The data transmission technology field of TYPE-A USB is also developing according to the above-mentioned mode.

The main purpose of the USB interface is to design a universal peripheral interface, and use one interface to solve the data transmission problem of the built-in, hard-to-plug interface such as PCI; the PS/2, serial, and parallel ports are different in specifications and diversified. Integrate the ports together, and at the same time solve the problem of easy damage to these pin connectors.

Therefore, the USB design was not made for convenience of plugging and unplugging, but an integrated, integrated, and easy-to-use interface. So in the early days of technology, the USB interface did not consider the plugging experience, not the size, etc. These factors were trivial at the time.

However, with the iterative upgrade and change of technology, after the TYPE-A USB is fully popularized and the cost is reduced, the later factors of the technology development model, namely performance, appearance, structure, user experience, etc., are also more in line with a technology-the law of technological change from small to large.

Reason three: cost factor

The third extremely important factor is naturally the cost issue.

The USB interface was born in 1994, and its specifications were jointly formulated by Intel, NEC, Compaq, DEC, IBM, Microsoft, and Northern Telecom. The inventor was Intel’s Ajay Bhatt (Ajay Bhatt).

In an interview with DesignNews in the early years, Bhatt mentioned some reasons why the USB interface was not directly plugged in.

Among them, cost is a very important reason. Bhatt believes that if the design is designed to be plugged in front and back, the number of connections and circuits will be doubled. In the early stage of the birth of new technology, the cost is in a sensitive period. Even more connections and circuits will greatly increase the cost and increase significantly-naturally increasing the price of the product.

In fact, after the establishment of the USB specification in 1994, the first-generation USB interface, namely USB 1.0, was officially released in 1996, two years later, but this interface can only be regarded as an early technical model and has no practical value.

In this case, for a technology that needs to be proven feasibility, increasing the cost is extremely unfavorable, and it is likely to hinder its promotion and replacement of existing mature technologies.

It was not until 1998 that the release of the USB 1.1 interface made the USB specification a truly usable standard interface.

How to identify the front and back of USB TYPE-A at a glance

In fact, the reason why the TYPE-C USB interface chooses a fool-like free plug design is that the technology maturity has reached a sufficiently high level, and the cost of USB technology has been well controlled. On this basis, improving performance and user experience has become a major trend in the development of the USB specification.

However, as stated at the beginning, TYPE-A USB still has a very high share, especially in the PC field, it is inseparable from TYPE-A USB. So how can you see the front and back of TYPE-A USB at a glance?

In fact, the TYPE-A USB is also designed with the distinction method in mind, but compared to those interfaces that use physical design to directly distinguish the front and the back, the TYPE-A USB distinction method is somewhat implicit.

In addition, it should be noted that in fact, many computers may not be able to grasp the pros and cons when designing the USB interface... It seems that this century's problem will not be completely solved until the TYPE-C interface is fully popularized.