To answer this question, we need to understand the concept of the system mask in relation to CPU interrupts.
The system mask is a mechanism used by the CPU to control the acceptance or rejection of interrupts. An interrupt is a signal that prompts the CPU to temporarily pause its current execution and handle a specific event or request.
Based on the given options:
A. Accept interrupts from a specific channel - This option is correct. The system mask allows the CPU to accept interrupts from a specific channel. By enabling the system mask for a specific channel, the CPU indicates that it wishes to receive interrupts from that particular channel.
B. Reject all interrupts - This option is incorrect. The system mask does not reject all interrupts. It provides a way for the CPU to selectively enable or disable interrupts from specific channels.
C. Reject selected interrupts - This option is incorrect. The system mask does not reject selected interrupts. It allows the CPU to specify which interrupts it wants to accept or reject based on the channel they originate from.
D. Reject all interrupts from selected channels - This option is incorrect. The system mask does not reject interrupts from selected channels. Instead, it allows the CPU to enable or disable interrupts on a per-channel basis.
Therefore, the correct answer is A) Accept interrupts from a specific channel. The system mask indicates whether the CPU wishes to accept interrupts from a specific channel.