Figure 10-1 DMA Unit Block Diagram

20-bit Adder/Subtractor

Adder Control

Logic

Timer Request

20

Transfer Counter Ch. 1

Destination Address Ch. 1

Source Address Ch. 1

Transfer Counter Ch. 0

Destination Address Ch. 0

Source Address Ch. 0

DMA

Control

Logic

 

 

 

 

 

 

 

DRQ1

 

Request

 

 

 

 

 

 

 

 

 

 

Selection

DRQ0

 

Logic

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Interrupt

Request

20

Channel Control Register 1

Channel Control Register 0

16

Internal Address/Data Bus

10.3PROGRAMMABLE DMA REGISTERS

The sections on the following pages describe the control registers that are used to configure and operate the two DMA channels.

10-2

DMA Controller

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AMD Am186TMER, Am188TMER user manual Programmable DMA Registers, DMA Controller