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AMD Geode SC1201 User Manual

Page 78

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78

AMD Geode™ SC1200/SC1201 Processor Data Book

General Configuration Block

32579B

3

BUS16 (16-Bit Wide Boot Memory). (Read Only) This bit reports the status of the BOOT16 strap (ball C8). If the BOOT16
strap is pulled high, at reset 16-bit access to ROM in the Sub-ISA interface is enabled. MCR[14] = 1 inverts the meaning of
this register.

0: 8-bit wide ROM.

1: 16-bit wide ROM.

2:1

Reserved. Write as read.

0

SDBE0 (Slave Disconnect Boundary Enable). Works in conjunction with the GX1 module’s PCI Control Function 2 Regis-
ter (Index 41h), bit 1 (SDBE1). Sets boundaries for when the GX1 module is a PCI slave.

SDBE[1:0]

00: Read and Write disconnect on boundaries set by bits [3:2] of the GX1 module’s PCI Control Function 2 register (Index

41h).

01: Write disconnects on boundaries set by bits [3:2] of the GX1 module’s PCI Control Function 2 register. Read discon-

nects on cache line boundary of 16 bytes.

1x: Read and Write disconnect on cache line boundary of 16 bytes.

This bit is reset to 1.

All PCI bus masters (including SC1200/SC1201 processor’s on-chip PCI bus masters, e.g., the USB Controller) must be dis-
abled while modifying this bit. When accessing this register while any PCI bus master is enabled, use read-modify-write to
ensure these bit contents are unchanged.

Offset 38h

Interrupt Selection Register - INTSEL (R/W)

Reset Value: 00h

This register selects the IRQ signal of the combined WATCHDOG and High-Resolution timer interrupt. This interrupt is shareable with
other interrupt sources.

7:4

Reserved. Write as read.

3:0

CBIRQ. Configuration Block Interrupt.

0000: Disable

0100: IRQ4

1000: IRQ8#

1100: IRQ12

0001: IRQ1

0101: IRQ5

1001: IRQ9

1101: Reserved

0010: Reserved

0110: IRQ6

1010: IRQ10

1110: IRQ14

0011: IRQ3

0111: IRQ7

1011: IRQ11

1111: IRQ15

Offset 39h-3Bh

Reserved - RSVD

Offset 3Ch

Device Identification Number Register - ID (RO)

Reset Value: xxh

This register identifies the device. SC1200 = 04h. SC1201 = 05h.

Offset 3Dh

Revision Register - REV (RO)

Reset Value: xxh

This register identifies the device revision. See the AMD Geode™ SC1200/SC1201 Processor Specification Update document for value.

Offset 3Eh-3Fh

Configuration Base Address Register - CBA (RO)

Reset Value: xxh

This register sets the base address of the Configuration block.

15:6

Configuration Base Address. These bits are the high bits of the Configuration Base Address.

5:0

Configuration Base Address. These bits are the low bits of the Configuration Base Address. These bits are set to 0.

Table 4-2. Pin Multiplexing, Interrupt Selection, and Base Address Registers (Continued)

Bit

Description

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