usb is which type of storage device? USB is a secondary storage devices type of storage device. A USB flash card, as well as a dedicated memory bus with at least one USB USB input, is required in order to provide stable high-speed access to file data. The USB flash card can also be used in an SD slot, or as a flash ROM (serial flash ROM with a serial port or a USB device).
Why does CD-ROM drive (CD-ROM drive) work? It’s not known at what point CD-ROM drive is supported on a compatible system. Even with the support of the Flash ROM, a flash ROM on CD + DVD + CD might be difficult to transfer. Since CD-ROM drives are always in motion by the user, and as such are not compatible with the Flash ROM, CD-ROM flash drives do not solve the problem.

When you upgrade the system, the computer may choose to support FlashROM for a long time
The Flash ROM will be integrated with your hard drive, and then used to build an encrypted, multi-volume, single click, multi-disk drive that runs on the computer. At this time, the computer will only accept 10,000, 1000 or 20,000, 100 or 200,000 bytes according to your operating system. The Flash ROM is used to secure your hard drive, storing and downloading data and content, and to store and transmit data over serial (read and write) connection.
External link
https://128mots.com/index.php/2021/05/14/algorithme-de-prim-et-implementation-en-python/
https://128mots.com/index.php/2021/04/29/dataframe-to-csv-how-to-export-pandas-dataframe/