Sometimes you need to use SSL/TLS protocol version 1.2 in your existing .NET 4.0 C# applications. The trick is that by default .NET 4.0 only supports TLS v1.0 and there is no standard way of forcing to use never TLS version. Why may you need a newer TLS version? Because some REST or WebService API providers have switched to using TLS v1.2 as a more secure and up-to-date protocol. 

When you get the following error, this may be also because of the outdated TLS version.

The request was aborted: Could not create SSL/TLS secure channel.

SDL stands for Simple DirectMedia Layer library. SDL is a cross-platform graphics library that provides low-level access to graphics, audio, keyboard hardware via OpenGL and Direct3D. SDL is well-ported to Windows, Mac OS, Linux, Android, and iOS. 

SDL is written in C, works with minimal effort with C++, also there are many bindings available for other languages like C#.

Simple SDL program example to explain rendering and keyboard handling

FreeRTOS is a free and open-source real-time operating system (RTOS) that runs on most of the modern microcontrollers, including STM32. In 2017, Amazon took control of the FreeRTOS project and now offers regular maintenance and support.

An operating system (OS) is software that manages other software and hardware resources in a computer system. You may be familiar with the most popular universal operating systems such as Windows, macOS, Linux, iOS, and Android. Universal OS is often designed to focus on the user experience.

A module definition DEF file (*. def) is a text file containing one or more module statements describing various attributes of a DLL. The DEF file is especially useful when one needs to disable the name mangling of the exported functions and variables.