A collection of memory cells, each with a unique physical address; its addressability varies from machine to machine.

A collection of memory cells, each with a unique physical address; its addressability varies from machine to machine.

• A. Register
• B. Memory
• C. Cache
• D. I/O Device

Answer: (B)

Memory is a large collection of storage cells, each with a unique physical address, allowing the system to read or write any location directly. This setup enables random access, meaning you can retrieve data from any address in roughly the same amount of time. The fact that addressability varies from machine to machine reflects architectural differences: different CPUs define different address widths, so the number of distinct addresses—and thus how much memory can be addressed—changes with the hardware. Registers, by contrast, are a tiny set of fast storage locations inside the processor and aren’t accessed via memory addresses in the same way. Cache is a small, ultra-fast layer of memory close to the CPU that also uses addresses, but it’s a specialized subset of memory rather than the main addressable storage. I/O devices are peripherals that may be accessed via separate I/O spaces or memory-mapped regions, not the primary memory described here.

Memory is a large collection of storage cells, each with a unique physical address, allowing the system to read or write any location directly. This setup enables random access, meaning you can retrieve data from any address in roughly the same amount of time. The fact that addressability varies from machine to machine reflects architectural differences: different CPUs define different address widths, so the number of distinct addresses—and thus how much memory can be addressed—changes with the hardware. Registers, by contrast, are a tiny set of fast storage locations inside the processor and aren’t accessed via memory addresses in the same way. Cache is a small, ultra-fast layer of memory close to the CPU that also uses addresses, but it’s a specialized subset of memory rather than the main addressable storage. I/O devices are peripherals that may be accessed via separate I/O spaces or memory-mapped regions, not the primary memory described here.