 We will now focus on the library built on top of the ThreadX. Let's start with the FileX. First of all, an overview of the FileX and of the LevelX, how is the project integration of FileX and LevelX through the STM32, Q by D, and Q by Max. Finally, we will take some minutes to implement a real file system on a real device. We will use a RAM disk. This is the reason I ask you to have that file, that source file in your hands. Let's start with the overview about FileX and LevelX. What is FileX? FileX is a size-automated, fat-compatible file system. Size-automated, size-automized, and high-performance, let's see. It's size-optimated because it has been created for embedded device. It supports an unlimited number of media, media like USB key, like SD card, like EMMC, like NAND, and NOR flash. No big deal, really, what is the physical device used below the library itself. The library is fault-tolerant because it prevents the corruption of the file, so the file system corruption, due to, for example, to interrupt, or due to some other tasks that enter, so the context switch, and so on. So it's really fault-tolerant. It has been certified by Tuve and by UL. By Tuve for electrical device, programmable, electronic device, medical device for the automotive industry, for the railway industry. It has been certified by UL on the other side for, let's say, home appliances, so electrical control for equipment for household or similar user, equipment for electricity, gas, oil, solar, thermal energy, and so on. This file system supports, let's say, the full range of FAT format, so from FAT 12 to FAT 16 to FAT 32, or even the extended FAT, in case you want to support more than four gigabytes in size. On the other side, we have LevelX, so not only the file system, but also the management of the NOR and NAND flash memories. The LevelX implement what is, for example, an EMMC controller in hardware. So what the EMMC controller makes in hardware, the LevelX makes in software. And it is used to implement what is called wear leveling, because since you know both the NAND and the NOR flash can only be erased and written a finite number of times, it's more critical to distribute the load and to distribute the flash memory usage in an even way. So this way, all the flash, the full flash, have the same level of, let's say, consumption. It's really fundamental to increase the disk lifetime, the device lifetime, the NAND and the NOR flash lifetime. Imagine, for example, you have a trivial example. You have a flash memory, one megabyte in size, guaranteed for 365 cycles of arrays and writes. And imagine also you want, for example, to write one kilobyte per day. It means that without the wear leveling, your application is going to write every day in the same location. So in one year, your flash is lost. With the wear leveling, so with the LevelX, let's say library, with this kind of protection, after 1,000 days or after three years, the wall flash has been written only one time. It means that the full amount of time needed before your flash memory is lost is no more one year, but is 1,000 year. This is a trivial example, not a real use case, but this allows to fully, let's say, understand what is the purpose of the LevelX. Quick overview about the API. The API are written in, let's say, in an easy way to understand. You have the API for the file system, file system underscore something, for the media, for the file itself, so create, read, write, sync, delete, et cetera, or for the directory management. So create, find, delete or something like this. So the root of the API is always fixed when dealing with a specific category of media or file or directory or flash or none, et cetera. Obviously, the FileX API are starting with FX. The LevelX API are starting with the LX. The full list, the full source code, the full package of API is distributed in ANSI C code, like the RTOS we saw this morning. And each function is self-contained in its own separate file. So every category of API you see here is in a dedicated file. We will see later on the project created by the Cubemix how it looks like.