SET ARMCC=C:\MDK529\ARM\ARMCC\bin SET PATH=%PATH%;%ARMCC%

(often referred to as ARMCC or RVCT -derived) is a legacy C/C++ compiler toolchain for ARM-based microcontrollers. It was the default compiler for Keil MDK (Microcontroller Development Kit) for many years before being replaced by Arm Compiler 6 (based on LLVM/clang).

After installation, the default compiler may still be Arm Compiler 6. You must manually switch projects to v5.