What does an adapter card allow the CPU to do?

An adapter card plays a crucial role in expanding the capabilities of a computer system by enabling communication between the central processing unit (CPU) and various internal and external devices. This function is vital for enhancing the overall functionality of the computer, as it allows the CPU to interact with peripherals such as printers, keyboards, and external drives, as well as internal components like graphics cards and sound cards.

Through the use of adapter cards, different types of connections and protocols can be utilized, depending on the device requirements. For instance, a graphics card adapter card allows the CPU to communicate with monitors and deliver high-quality visual output, while a network card enables access to network devices and the internet.

The other options relate to functions that are not directly handled by adapter cards. Upgrading memory involves adding RAM or replacing existing modules, which doesn't pertain to adapter cards. Increasing processing speed is primarily an attribute of the CPU's architecture and clock speed rather than something that can be achieved through an adapter. Lastly, storage capacity is determined by drives like hard disks or solid-state drives, rather than adapter cards. Therefore, the defining feature of the adapter card is its role in enabling communication with various devices, making it foundational for the computer's connectivity and functionality.