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296 AMD Geode™ SC1200/SC1201 Processor Data Book
Core Logic Module - ISA Legacy Register Space
32579B
6.4.7 ISA 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.