The full name of USB is Universal Serial Bus, which can connect up to 127 peripherals, and the USB interface has become the standard interface for scanners because of its support for hot-plugging and the advantages of plug-and-play.
There are two specifications for USB, USB1.1 and USB2.0.
USB1.1 is the more popular USB specification, its high-speed mode transmission rate is 12Mbps, low-speed mode transmission rate is 1.5Mbps. note: here b is the meaning of Bit, 1MB/s (megabytes per second) = 8MBPS (megabits per second), 12Mbps = 1.5MB/s. At present, the home low-end scanners are mainly for the USB interface type.
The USB 2.0 specification evolved from the USB 1.1 specification. It achieves a transfer rate of 480Mbps, which translates to 60MB/s, enough to meet the rate requirements of most peripherals.The Enhanced Host Controller Interface (EHCI) in USB 2.0 defines an architecture compatible with USB 1.1. It allows the use of the USB 2.0 interface with the USB 2.0 interface, which can be used with the USB 2.0 interface. It is possible to drive USB 1.1 devices with USB 2.0 drivers. This means that any device that supports USB 1.1 can be used directly on a USB 2.0 interface without having to worry about compatibility issues, and that accessories such as USB cables, plugs, and so on can also be used directly.
Nowadays, hosts have USB ports, so USB optical storage applications are extremely convenient, and as an interface for external optical storage devices, the application is quite flexible, and there is no need to add additional equipment for the interface, reducing investment.