AMD SC2200 manual ISA Legacy Register Space, DMA Channel Control Registers

Core Logic Module - ISA Legacy Register Space 32580B

6.4.7ISA Legacy Register Space

The ISA Legacy registers reside in the ISA I/O address space in the address range from 000h to FFFh and are accessed through typical input/output instructions (i.e., CPU direct R/W) with the designated I/O port address and 8-bit data.

The bit formats for the ISA Legacy I/O Registers plus two chipset-specific configuration registers used for interrupt mapping in the Core Logic module are given in this section. The ISA Legacy registers are separated into the following categories:

•DMA Channel Control Registers, see Table 6-43

•DMA Page Registers, see Table 6-44

•Programmable Interval Timer Registers, see Table 6-45

•Programmable Interrupt Controller Registers, see Table 6-46

•Keyboard Controller Registers, see Table 6-47

•Real-Time Clock Registers, see Table 6-48

•Miscellaneous Registers, see Table 6-49(includes 4D0h and 4D1h Interrupt Edge/Level Select Registers)

		Table 6-43. DMA Channel Control Registers
Bit	Description
I/O Port 000h		DMA Channel 0 Address Register (R/W)
Written as two successive bytes, byte 0, 1.
I/O Port 001h		DMA Channel 0 Transfer Count Register (R/W)
Written as two successive bytes, byte 0, 1.
I/O Port 002h		DMA Channel 1 Address Register (R/W)
Written as two successive bytes, byte 0, 1.
I/O Port 003h		DMA Channel 1 Transfer Count Register (R/W)
Written as two successive bytes, byte 0, 1.
I/O Port 004h		DMA Channel 2 Address Register (R/W)
Written as two successive bytes, byte 0, 1.
I/O Port 005h		DMA Channel 2 Transfer Count Register (R/W)
Written as two successive bytes, byte 0, 1.
I/O Port 006h		DMA Channel 3 Address Register (R/W)
Written as two successive bytes, byte 0, 1.
I/O Port 007h		DMA Channel 3 Transfer Count Register (R/W)
Written as two successive bytes, byte 0, 1.
I/O Port 008h (R/W)
Read		DMA Status Register, Channels 3:0
7	Channel 3 Request. Indicates if a request is pending.
	0:	No.
	1:	Yes.
6	Channel 2 Request. Indicates if a request is pending.
	0:	No.
	1:	Yes.
5	Channel 1 Request. Indicates if a request is pending.
	0:	No.
	1:	Yes.
4	Channel 0 Request. Indicates if a request is pending.
	0:	No.
	1:	Yes.
3	Channel 3 Terminal Count. Indicates if TC was reached.
	0:	No.
	1:	Yes.
AMD Geode™ SC2200 Processor Data Book			305