Link modes (BOOT/APP)
Every Tachyon device contains 2 internal programs: the firmware and the bootloader. When the device starts up, the bootloader initializes the device and starts the firmware. The bootloader also performs other functions such as firmware updates and device identification.
Both the bootloader and the firmware contain an implementation of the TachyonLink protocol. The device can connect to a PC while it is running either the firmware (APP mode) or the bootloader (BOOT mode) code.
Due to software dependencies, hardware permissions and security, some features can only be executed in a certain mode. Firmware updates must be performed by the bootloader. Since the bootloader is write-protected, the device firmware can be restored through BOOT mode even if the firmware is corrupted. On the other hand, the bootloader cannot determine what firmware is installed on the device, therefore it is not possible to upload graphics packs or settings in BOOT mode, for example.
Normally, the Tachyon device is set up to reject BOOT mode connections, unless the DOWN button is pressed. The device can also be switched to a different mode after a connection is made in the 'Advanced' tab of TachyonLink.