This floppy set uses the BIOS instead of the linux driver. You can boot SliTaz using unsupported floppy drives such as some PCMCIA devices.
The web version of 4.0 is launched by default - the filesystem is mounted from the web. You can select memtest or ipxe with the up, down and enter keys (the boot menu is built with this tool).
Start your computer with fd001.img. It will show the kernel version string and the kernel cmdline line. You can edit the cmdline. Most users can just press Enter.
The floppy is then loaded into memory (one dot each 64KB) and you will be prompted to insert the next floppy, fd002.img. And so on up to fd003.img.