There are two methods of I/O transfer in minicomputers. These are programmed data transfer and direct memory access. The programmed data transfer is a slow but flexible method of I/O transfer. Some form of interrupt system may be used with this method. Transfer takes place between an I/O bus and one or more of the CPU registers. This is usually in the form of a parallel transfer of one computer word or one eight-bit byte. Because of the time requirement of the execution of the program, maximum of 30 to 40 thousand words per second is the upper limit for the highest priority device. The programmed data transfer is used for control of peripheral device and for checking the status. Its use is required where the computer must act on all incoming data as it is received.
DMA is usually used to make block transfers by stealing memory cycle from the running program at the rates up to one word per memory cycle. The maximum DMA transfer rates from one half to more than one million words per second are typical. The word counter and the memory address register are usually contained in the DMA channel hardware, although sometimes they are located in the device controller. Transfer normally takes places between the device controller and memory without disturbing the CPU except that one memory cycle is stolen by the channel for each transfer. An interrupt is provided for the CPU when a transfer of the block data has been accomplished.
In this dissertation we have developed both of these techniques of transferring data and signals between computer and the external device. As an application of these interfaces two experiments were made. One is application to the deadbeat controller and another is an application to the determination of the probability density of the quantizer input in PCM for korean speech.
Experiment of deadbeat controller, which is a digital control system with minimum settling time as the performance objective, uses the programmed data transfer scheme. For this deadbeat controller discrete time systems and sampled-data systems are investigated. Experiment determining the probability density of the quantizer input in PCM for Korean speech uses the DMA data transfer scheme. Experimental result reveals that the probability density function of the amplitude of the speech signal can be approximated by a Gamma density.
미니 컴퓨터의 interface design에는 2가지 데이터 전달방식이 사용된다. 하나는 program에 의한 데이터 전달방식이고 다른하나는 direct memory access에 의한 데이터 전달방식이다.
Program에 의한 데이터 전달방식에 의한 interface design은 가격이 적게 들고 다양한 기능을 가지며 설계하기 용이하나 데이터 전달속도가 느리며 값이 싼 CPU의 시간을 많이 소비하는 단점이 있다. Direct memory access에 의한 interface design은 설계하기가 복잡하고 가격이 많이 드나 데이터 전달속도가 빠르며 CPU의 Time을 절약할 수 있는 이점이 있다.
NCVA 840 Computer의 A/D, D/A converter의 interface를 설계 및 제작하는데 이들 2가지 방법을 모두 사용하였으며 이들의 interface를 이용하여 2가지 실험을 하였다. 첫 번째 실험인 deadbeat controller 실험에서 sampling time을 2초로 하였으며 그결과 4초 이내의 settling time으로 진동없이 정상상태에 도달하였다. 이 실험에서 한국어의 분포함수는 Gamma 분포함수라는 결과를 얻었으며 이는 한국어도 영어와 같은 분포라는 것을 알 수 있다.
