S/36s had two sixteen-bit processors, the CSP or Control Storage Processor, and the MSP or Main Storage Processor. The MSP was the workhorse; it performed the instructions in the computer programs. The CSP was the governor; it performed system functions in the background. Special utility programs were able to make direct calls to the CSP to perform certain functions; these are usually system programs like $CNFIG which was used to configure the computer system. These two processors worked in tandem, and it's one reason the S/36 worked so well.