Which of the following statements about Read Only Memory (ROM) are correct? A.…

Concept: Computer memory is classified by volatility. Non-volatile memory keeps its stored bit pattern when the supply voltage is removed; volatile memory loses it. Read Only Memory (ROM) is the non-volatile family that holds firmware which must already be present the instant a machine is powered up, while Random Access Memory (RAM) is the volatile working store into which the processor loads programs and data while the system is running.

Concept: A second principle governs capacity pressure. When the working store (RAM) runs short, the operating system pages inactive pages out to the hard disk — this is virtual memory. Capacity pressure and disk paging are therefore properties of RAM. ROM holds a firmware image that is written by a separate programming or firmware-update step rather than by running programs, so it does not fill up as programs execute and never triggers this behaviour.

Application: each of the four statements is tested against these two principles.

1. Statement A — the contents remain intact even when the power to the ROM is turned off. Non-volatility is the defining property of the ROM family, and every member achieves it by a mechanism that does not depend on the supply voltage: mask ROM fixes the bit pattern in the chip wiring at manufacture, PROM sets it during programming by permanently altering one-time-programmable links (a fusible link is blown open, while an antifuse link is instead formed into a conducting path), and EPROM, EEPROM and flash hold trapped charge on floating gates. The stored pattern therefore survives a power-off, and the statement holds.

2. Statement B — ROM is often used to store the start-up instructions when the computer is first switched on. At power-on, RAM is empty, so the bootstrap code (the BIOS or UEFI firmware that initialises hardware and loads the operating system) must come from a memory that was already programmed. That firmware lives in ROM, so the statement holds.

3. Statement C — as the ROM becomes full, the processor has to continually access the hard disk. Continual disk access driven by shortage of space is the paging behaviour of RAM under virtual memory, not of ROM: a ROM image is fixed at programming time and does not fill up as programs run. The statement does not hold.

4. Statement D — ROM is a volatile memory. This is the negation of statement A. ROM retains its contents without power, so it is non-volatile and the statement does not hold. Note that statements A and D are mutually contradictory, so no correct selection can contain both.

Cross-check: contrasting the two memory families on the properties the four statements touch confirms the result.

Result: statements A and B hold and statements C and D do not, so the selection that matches the memory is "A and B only".