Page15 about Mach3: Unfortunately, the software is currently for Windows only, so Linux users will have to beg, borrow, or steal a machine outfitted with the OS until it's been converted.
You don't need to change the OS. For Linux there is LinuxCNC (originally known as EMC2, enhanced machine controller). It's based on a realtime extenstion to the Linux kernel (Xenomai) for the critical parts and a GUI. It also includes a ladder-logic PLC to automate parts of a machine. The G-Code preview is rendered using OpenGL.
There is a quite strong community around LinuxCNC (as with Mach3 as well), both are used very successfully to retrofit old machines (with broken controllers or to upgrade manual machines).
The author has covered many good examples of freeware but obviously cannot list all of them. KiCAD is already fairly well known, as is LTspice. I think the author's intent is to list not-so-well-known freeware, and I applaud his efforts.
Readers' comments as to other good examples of freeware are very useful too, and add informative detail to the original article.
What are the engineering and design challenges in creating successful IoT devices? These devices are usually small, resource-constrained electronics designed to sense, collect, send, and/or interpret data. Some of the devices need to be smart enough to act upon data in real time, 24/7. Are the design challenges the same as with embedded systems, but with a little developer- and IT-skills added in? What do engineers need to know? Rick Merritt talks with two experts about the tools and best options for designing IoT devices in 2016. Specifically the guests will discuss sensors, security, and lessons from IoT deployments.