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一、PLA的一般概念1.概念随着半导体存贮技术的日益发展,它的应用范围现已进一步渗透到随机逻辑领域中。这就为简化硬件的逻辑设计、减少出错、便于校验、降低机器造价等带来了好处。在已有广泛应用的ROM及PROM的基础上,近年来,又出现了一种称之为可编程序逻辑阵列(Programable Logic Array,简称PLA)这样一种控制存贮器技术。这种PLA实际上是只读存贮器(ROM)发展中的一个分支。那么,这种PLA是什么原因推动它出现、发展起来的呢?这是因为人们在生产实践中发现,尽管ROM较之原来的组合逻辑规整、方便,便于维护、检修,但仍觉得它的性能不够完善。比如,为了降低机器的造价,进一步减少ROM的容量,特别是当ROM用作控存时,总是希望同一条微指令不要多次重复出现,在微程序的公用性问题上,用它就不能令人满意地解决问题。由于
First, the general concept of PLA 1. Concept With the growing semiconductor storage technology, its scope of application has now further penetrated into the field of random logic. This is to simplify the logic of hardware design, reduce errors, easy to verify, reduce machine cost and other benefits. On the basis of ROM and PROM that have been widely used in recent years, there has been another kind of control memory technology called a programmable logic array (PLA). This PLA is actually a branch in the development of read-only memory (ROM). So, what is the reason for this PLA to promote its emergence and development? This is because people found in practice, although the ROM than the original combination of logic, convenient, easy to maintain, overhaul, but still feel its performance Not good enough. For example, in order to reduce the cost of the machine to further reduce the ROM capacity, especially when the ROM is used as a memory controller, it is always hoped that the same micro-instruction will not be repeated many times. With respect to the commonality of the micro-program, it can not be used Resolve the problem satisfactorily. due to