micro-evtd dates all the way back to the first generation of Linkstation devices (pre-ARM) and is used to control the on-board microcontroller used by the early Linkstations and virtually every model of Terastation (see Terastation Microcontroller Interface). This includes a simple function for sending commands to the microcontroller as well as functionality to automatically adjust fan speeds based on system temperature and other such system management functions.
Later an updated version was created for use with the early ARM-based Linkstations which has been packaged for use with the mainline Debian Installer for Orion5x-based Linkstation Devices, mainly the LS-GL (LSPRO). That version is still available in the Debian repository but many of its functions are specific to the Linkstation/Kurobox PRO devices. In fact it will throw a "device is not supported" error if you try to install it on other devices.
Recently I created a fork of the original version which fixes a bug that prevented longer commands from working (LCD commands and version checking) and compiled it for ARMEL/ARMHF/PowerPC and AMD64 for use in my Debian Installer projects. I did this mainly because there is a hard ~7MB limit for installer images on the older devices which is too small to easily include a Python3 environment inside the installer.
For most applications it is likely easier to use the Python library than to use micro-evtd but if you need something to run in a very small environment or an older environment (like the stock firmware) micro-etvd is still a useful alternative.
That project can be found here: