顾名思义,只读存储器(只读存储器) cannot be written to. The contents of the memory are decided during the design process and data is programmed during the manufacturing process. As such, 只读存储器 is very cheap in terms of space and also has good timing and power characteristics. It is also non-volatile, retaining its contents indefinitely. It is often used for holding program parts which will not change during the life of the product, lookup tables, and other data that is constant.
ROM 出现在 1965 年,尽管在 256 位时它们并没有进入许多大众市场产品。 直到桌面计算器和后来的视频游戏行业的诞生,它们才成为大批量零件。 早期的设备使用二极管矩阵,但后来的设备采用掩模编程。
虽然当今大多数系统都需要一定程度的可重编程性,但由于成本的原因,ROM 仍在许多设备中使用,并且辅以少量的一次性可编程(一次性密码) 或可重新编程的存储器,例如闪存。 ROM 电路和实现仍在开发中,2009 年发布了一项新**,用于每个单元保持多个位的 ROM 单元,以及 2012 年为 FinFET 设备实现 ROM 的**。