AMD SC2200 manual Standard Configuration Registers

SuperI/O Module 32580B

Table 5-3provides the bit definitions for the Standard Con- figuration registers.

•All reserved bits return 0 on reads, except where noted otherwise. They must not be modified as such modifica- tion may cause unpredictable results. Use read-modify-

write to prevent the values of reserved bits from being changed during write.

•Write only registers should not use read-modify-write during updates.

	Table 5-3. Standard Configuration Registers
Bit	Description
Index 07h	Logical Device Number (R/W)

This register selects the current logical device. See Table 5-2for valid numbers. All other values are reserved.

7:0 Logical Device number.

Index 20h-2Fh SIO Configuration (R/W)

SIO configuration and ID registers. See Section 5.4.1 "SIO Control and Configuration Registers" on page 103 for register/bit details.

Index 30h	Activate (R/W)
7:1	Reserved.

0Logical Device Activation Control.

0:Disable.

1:Enable.

Index 60h	I/O Port Base Address Bits [15:8] Descriptor 0 (R/W)
7:0	Descriptor 0 A[15:8]. Selects I/O lower limit address bits [15:8] for I/O Descriptor 0.
Index 61h	I/O Port Base Address Bits [7:0] Descriptor 0 (R/W)
7:0	Descriptor 0 A[7:0]. Selects I/O lower limit address bits [7:0] for I/O Descriptor 0.
Index 62h	I/O Port Base Address Bits [15:8] Descriptor 1 (R/W)
7:0	Descriptor 1 A[15:8]. Selects I/O lower limit address bits [15:8] for I/O Descriptor 1.
Index 63h	I/O Port Base Address Bits [7:0] Descriptor 1 (R/W)
7:0	Descriptor 1 A[7:0]. Selects I/O lower limit address bits [7:0] for I/O Descriptor 1.
Index 70h	Interrupt Number (R/W)
7:4	Reserved.
3:0	Interrupt Number. These bits select the interrupt number. A value of 1 selects IRQ1, a value of 2 selects IRQ2, etc. (up to
	IRQ12).
	Note: IRQ0 is not a valid interrupt selection.
Index 71h	Interrupt Request Type Select (R/W)
Selects the type and level of the interrupt request number selected in the previous register.
7:2	Reserved.

1Interrupt Level Requested. Level of interrupt request selected in previous register.

0:Low polarity.

1:High polarity.

This bit must be set to 1 (high polarity), except for IRQ8#, that must be low polarity.

0Interrupt Type Requested. Type of interrupt request selected in previous register.

0:Edge.

1:Level.

Index 74h	DMA Channel Select 0 (R/W)
Selects selected DMA channel for DMA 0 of the logical device (0 - the first DMA channel in case of using more than one DMA channel).
7:3	Reserved.
2:0	DMA 0 Channel Select. This bit field selects the DMA channel for DMA 0.
	The valid choices are 0-3, where a value of 0 selects DMA channel 0, 1 selects channel 1, etc.
	A value of 4 indicates that no DMA channel is active.
	Values 5-7 are reserved.
AMD Geode™ SC2200 Processor Data Book		101