The Processor Control Register (PCR) contains a bit that controls whether the CPU is executing instructions in user or kernel mode. The task data structure for each process contains an integer utime field that keeps track of how much CPU time each process has spent in user mode.

1. Explain in detail how the utime field in the task data structure is updated on each clock tick. Include all changes made to the PCR and Program Counter (PC).

2. Explain in detail how the system call usertime()can return to the user process the contents of the utime field. Include all changes made to the PCR, PC and other registers.