A Process Control Block (PCB) does not contain which of the following?

Concept

A Process Control Block (PCB) is the per-process bookkeeping structure the operating system keeps for every process it has created. It does not hold the raw bytes of a program; instead it records the information the OS needs to manage and resume that one process: process state, program counter, CPU registers, scheduling and priority information, memory-management information (the base/limit values and pointers that locate the process's code, data and stack segments in memory), accounting information, and I/O status. So the code, data and stack of a process are described by its PCB even though the bytes themselves live in the process's address space. Crucially, a PCB exists only for a process that has been created.

Applying it to the options

Read the stem carefully: it asks which item has no place in a per-process PCB at all.

• Code, Data and Stack each belong to a specific process. The PCB's memory-management fields hold the base/limit values and pointers that record where these segments are, so each of them is part of the process picture the PCB maintains. They are not the odd one out.

• Bootstrap program is firmware/boot code that runs once at power-on or reboot to initialise the machine and load the operating system. It executes before the OS has created any process, so no PCB even exists yet, and it belongs to no process. It is therefore never represented in any PCB.

Result

Among the four, only the bootstrap program has no association with any process, so it is the one a PCB does not contain. This is why "Both Code and Bootstrap program" is not the intended reading: the PCB does keep the memory-management metadata for a process's code, while the bootstrap program lies entirely outside the process world. (A PCB is also called a Task Control Block.)