INTRODUCTION TO MICROPEOCESSOR
MICROCOMPUTER SYSTEM
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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CWCR
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BA and BWC
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CAR
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CAR and CWCR
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Detailed explanation-1: -The current address register (CAR) is used to hold the 16-bit memory address used for the DMA transfer. The current word count register (CWCR) programs a channel for the number of bytes (up to 64K) transferred during a DMA action.
Detailed explanation-2: -Intel 8237 is a direct memory access (DMA) controller, a part of the MCS 85 microprocessor family. It enables data transfer between memory and the I/O with reduced load on the system’s main processor by providing the memory with control signals and memory address information during the DMA transfer.
Detailed explanation-3: -The term DMA stands for direct memory access. The hardware device used for direct memory access is called the DMA controller. DMA controller is a control unit, part of I/O device’s interface circuit, which can transfer blocks of data between I/O devices and main memory with minimal intervention from the processor.