What is a ROM (Read Only Memory) chip

A ROM chip (Read Only Memory) is a non-volatile memory integrated circuit that stores data permanently, retaining its contents even when the device is powered off. It typically holds firmware or boot/configuration information that the system must be able to read reliably.

Typical characteristics:

• Non-volatile: data remains without power.

• Read-focused: contents are meant to be read; writing may be impossible or only possible with special procedures/tools depending on the type.

• Common uses: BIOS/UEFI, bootloaders, microcode, configuration tables, peripheral firmware.

Common variants (by technology):

• Mask ROM: factory-programmed, not writable.

• PROM: one-time programmable.

• EPROM: erasable (often via UV) and reprogrammable.

• EEPROM / Flash: electrically erasable and rewritable (Flash is widely used for modern firmware).