顧名思義，只讀存儲(chǔ)器(只讀存儲(chǔ)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, 只讀存儲(chǔ)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 出現(xiàn)在 1965 年，盡管在 256 位時(shí)它們并沒(méi)有進(jìn)入許多大眾市場(chǎng)產(chǎn)品。 直到桌面計(jì)算器和后來(lái)的視頻游戲行業(yè)的誕生，它們才成為大批量零件。 早期的設(shè)備使用二極管矩陣，但后來(lái)的設(shè)備采用掩模編程。

雖然當(dāng)今大多數(shù)系統(tǒng)都需要一定程度的可重編程性，但由于成本的原因，ROM 仍在許多設(shè)備中使用，并且輔以少量的一次性可編程(一次性密碼) 或可重新編程的存儲(chǔ)器，例如閃存。 ROM 電路和實(shí)現(xiàn)仍在開(kāi)發(fā)中，2009 年發(fā)布了一項(xiàng)新**，用于每個(gè)單元保持多個(gè)位的 ROM 單元，以及 2012 年為 FinFET 設(shè)備實(shí)現(xiàn) ROM 的**。