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NEe Microcomputers, Inc.
NEe
JLPD8257 JLPD8257·5
PROGRAMMABLE DMA CONTROLLER
DESCR IPTION
The !1PD8257-5 is a programmable four-channel Direct Memory Access (DMA) controller. It is designed to simplify high speed transfers between peripheral devices and memories. Upon a peripheral request, the !1PD8257-5 generates a sequential memory address, thus allowing the peripheral to read or write data directly to or from memory. Peripheral requests are prioritized within the !1PD8257-5 so that the system bus may be acquired by the generation of a single HOLD command to the 8080A. DMA cycle counts are maintained for each of the four channels, and a control signal notifies the peripheral when the preprogrammed member of DMA cycles has occurred.
UPD8257-5 Datasheet
