Assertion (A): Overlays were used in early computer systems to run programs that were larger than the physical main memory size available.
Reason (R): Overlays keep only the active instructions and data in memory at any given time, swapping components manually without absolute operating system automation support.
Assertion (A) is True: The primary purpose of the overlay technique in early computer systems was to allow programs larger than the physical main memory (RAM) to execute by loading them in pieces as needed.
Reason (R) is True: Overlays work by keeping only the currently active instructions and data in memory, loading and swapping modules in and out of the same memory space as required, historically managed by the programmer without transparent OS-level virtual memory support.
Relationship between Assertion and Reason: Reason (R) correctly explains how overlays achieve Assertion (A)—by keeping only active instructions/data in memory through swapping, programs larger than physical memory are successfully able to run.