The crossword solution for the term 'semi-essential part' is CAB, which stands for Centralized Administrative Block. This is a type of computer architecture that consists of a single central processing unit (CPU) and multiple peripheral devices connected to it. The CPU is responsible for controlling the operations of the peripheral devices, while the peripheral devices provide input and output capabilities. The CAB architecture is used in many modern computers and is considered semi-essential because it allows for efficient use of resources and improved performance.