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只读存贮器(ROM)采用过变压器形、电容形、电阻形、二极管、磁扭线、磁膜、磁线、或金属卡片等各种方式,但都没有完全满足ROM所要求的诸条件,还不能在所有的数字机器中应用。而最近,随着集成电路技术的发展,已出现了充分满足单位价格,位密度、工作速度、和逻辑IC的兼容性、可靠性以及功耗等要求的ROM IC,并且很容易弄到手。其中有一种可编程序只读存贮器(PROM),使用这种存贮器就可以自由地写入或改写存贮数据,从而使运算时间减短,容易使用,这样就使得它在计算机、控制装置的微程序设计、或代码转换器、字符发生器、微处理机的程序存贮器及一般的逻辑电路等这些通常不采用掩模型ROM IC的地方得到了广泛的应用。本文简单地叙述一下PROM的种类、特征和最基本的应用例子。
ROM has been used in a variety of ways such as transformers, capacitors, resistors, diodes, magnetic twisted wires, magnetic films, magnetic wires, or metal cards, but none completely satisfy the requirements of the ROM , Can not be used in all digital machines. Recently, with the development of integrated circuit technology, ROM ICs that fully meet the unit price, bit density, operation speed, compatibility with logic ICs, reliability and power consumption have emerged and are easy to find. Among them is a programmable read-only memory (PROM), which can be used to write or rewrite the stored data freely, so that the operation time is shortened and easy to use, thus making it in the computer, Microprogramming of control devices or applications such as transcoders, character generators, microprocessor program memories, and general logic circuits, which typically do not employ masked ROM ICs, are widely used. This article briefly describes the types, features and the most basic examples of PROMs.