Intel 80C186XL DxDSTL, Register Name:DMA Destination Address Pointer Low, Register Mnemonic

DIRECT MEMORY ACCESS UNIT

Register Name:DMA Destination Address Pointer (Low)

Register Mnemonic: DxDSTL

Register Function:Contains the lower 16 bits of the DMA Destination pointer.

15

D	D	D	D
D	D	D	D
A	A	A	A
1	1	1	1
5	4	3	2

D D A 1 1

D D A 1 0

D D A 9

D D A 8

D	D	D
D	D	D
A	A	A
7	6	5

D D A 4

			0
D	D	D	D
D	D	D	D
A	A	A	A
3	2	1	0

A1179-0A

Bit	Bit Name	Reset	Function
Mnemonic		State
DDA15:0	DMA	XXXXH	DDA15:0 are driven on the lower 16 bits of the
	Destination		address bus during the deposit phase of a DMA
	Address		transfer.

Figure 10-10. DMA Destination Pointer (Low-Order Bits)

10.2.1.2Selecting Byte or Word Size Transfers

The WORD bit in the DMA Control Register (Figure 10-11) controls the data size for a channel. When WORD is set, the channel transfers data in 16-bit words. Byte transfers are selected by clearing the WORD bit. The data size for a channel also affects pointer indexing. Word transfers modify (increment or decrement) the pointer registers by two for each transfer, while byte trans- fers modify the pointer registers by one.

10-14