PC-compatible PLC with the free access is not the group of the PLC directly compatible with PC, but the PLC which don't have the integrated run-time and which are often delivered without an operating system. Architecture of the such PLC may be different, ranging from cost-effective solutions with the x86 architecture and ending decisions ARM and MIPS. Run-time of the such PLC is usually formed from the software of the same with the hard-programmable PLC class, the result of which is an executable binary file in one of the most common, scalable, or specialized operating system (DOS, QNX, Linux, WinCE, VxWorks). Frequently the specialized solutions for the problem can be met. As an example of this class it can be the PLC of PC/104 form factor.