 The MINIX 3 microkernel, for example, has only approximately 12,000 lines of code.Microkernels trace their roots back to Danish computer pioneer Per Brinch Hansen and his tenure in Danish computer company Regnecentralen where he led software development efforts for the RC 4000 computer.In 1967, Regnecentralen was installing a RC 4000 prototype in a Polish fertilizer plant in Puławy.