CDK4NIOS stands for Cross Development Kit for Altera's soft core processor NIOS and should you support with a comprehensive Assembler and C/C++ development environment under Linux. It will present only free of fee tools, so you can use it without risks.
FOCA (Fudeba: Optimizer, Compiler and Assembler) is a free development system for the MSX architecture (Z80-based), aiming to provide developer support for the Uzix operating system.