Understand the need for secondary storage and the principles, advantages and disadvantages of magnetic, optical and solid state storage.

For the high-performance laptop, recommend solid state storage (an SSD). It stores bits in flash transistors with no moving parts, so it gives very fast access, is durable against knocks, silent and low power, which suits a portable, performance-focused machine. Its higher cost per byte and limited write cycles are acceptable trade-offs for the speed and durability.

For long-term archival backups, recommend magnetic storage (hard disk drives) or optical media. Magnetic drives give the highest capacity at the lowest cost per byte, which suits storing large volumes cheaply; the slower speed from moving parts matters little for backups that are written occasionally and read rarely.

Markers reward an SSD for the laptop with reasons (speed, durability, no moving parts) and a high-capacity, low-cost option for archival with reasons (capacity, cost per byte), each tied to the working principle.

Secondary storage is needed because main memory (RAM) is volatile, losing its contents when power is removed, and is relatively small and expensive. A non-volatile, high-capacity store is therefore required to keep programs and files permanently between sessions.

Magnetic storage, such as a hard disk drive, works by storing each bit as a magnetised region on rapidly rotating platters. A read/write head moves across the spinning platters to magnetise regions (write) or detect their magnetisation (read), with the direction of magnetisation representing a 0 or a 1.

Markers reward the volatility and capacity reasons for needing secondary storage and a correct description of magnetised regions on rotating platters read by a moving head.