Posted on July 9, 2024 in Technology

USB 1-4

USB 1.0 was the first major creation of USB standards, made in 1996. It could transfer data at a rate between 1.5 and 12 Mbps, and was not widely adopted by tech companies. 1.1, which had several improvements on the initial product, was adopted by Apple for the iMac G3, which swapped that device off of serial and parallel ports and set USB onto the trajectory it’s been on ever since.

2.0 was made in 2000, and could transfer data at 480 Mbps, but generally hung around 280 Mbps due to hardware limitations in the devices that had it. 2.0 was backwards compatible, and could also allow two devices to talk to each other without a computer in the middle. 2.0 can communicate with most other kinds of USBs introduced later, except for USB-C. USB 2.0 was also now capable of (or at least better known for) delivering power, and could manage about 500 mA at 5 V.

 3.0 (and 3.1 and 3.2) is a faster, more powerful version that was introduced in 2008. USB 3.0 devices can achieve up to 5 Gbps data transfer rate, 10 times what USB 2.0 can do, and can deliver up to 900 mA of power, at 5 V. USB 3.0 ports and connectors usually have blue in them somewhere to distinguish them from USB 2.0 ports and connectors. 3.0 also allowed for data to flow both ways at the same time between devices, and remained backwards-compatible with 2.0 (but not 1.1). These connectors doubled the number of data channels in the USB, which is what allowed for the speed and power of the 3.0.

3.1 did not change much except for the data transfer rate, which shot up to 10 Gbps, and 3.2 doubled it again to 20 Gbps. In combination with the USB-C, it can transfer 10 Gbps both ways!

4.0 can manage up to 40 Gpbs, but is also available in a 20 Gbps variation, and can deliver 240 W of power over the (confusingly named) 3.1 power standard. That’s the same wattage coming out of most American wall plugs!

Aside from 1.1 (which is multiple decades old at this point) most of these plugs can communicate with each other, across the gaps of time. USB-C is an exception at USB 2.0, and this can present issues if these two are somehow expected to talk to each other, like they might if an older computer is being used to supplement equipment (like lab or tooling equipment) that cannot use more modern versions of Windows. However, the average person is unlikely to encounter these issues on the equipment they use day – to – day, and even if they did, odds are they would be able to use an intermediary computer to jump from 2.0 to 3.0, and then from there to USB-C. Not ideal, but not unsolveable, like a number of the issues created by serial/parallel port crossovers were!

Sources: https://www.digikey.com/en/articles/decoding-the-usb-standards-from-1-to-4