SC3200 datasheet(229/447 Pages) AMD

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AMD Geode™ SC3200 Processor Data Book

229

Core Logic Module - Bridge, GPIO, and LPC Registers - Function 0

Revision 5.1

Index 8Eh

VGA Timer Count Register (R/W)

Reset Value: 00h

7:0

VGA Timer Load Value. This field represents the load value for VGA Timer. It is loaded into the counter when the timer is

enabled (F0 Index 83h[3] = 1). The counter is decremented with each clock of the configured timebase (F0 Index 8Bh[6]).

Upon expiration of the counter, an SMI is generated and the status is reported at F1BAR0+I/O Offset 00h/02h[6] (only).

Once expired, this counter must be re-initialized by either disabling and enabling it, or by writing a new count value in this

Note:

Although grouped with the power management Idle Timers, the VGA Timer is not a power management function.

It is not affected by the Global Power Management Enable setting at F0 Index 80h[0].

Index 8Fh-92h

Reserved

Reset Value: 00h

Index 93h

Miscellaneous Device Control Register (R/W)

Reset Value: 00h

Floppy Drive Port Select. Indicates whether all system resources used to power manage the floppy drive use the primary,

or secondary FDC addresses for decode.

0: Secondary.

1: Primary.

Reserved. Must be set to 1.

Partial Primary Hard Disk Decode. This bit is used to restrict the addresses which are decoded as primary hard disk

accesses.

0: Power management monitors all reads and writes to I/O Port 1F0h-1F7h, 3F6h-3F7h (excludes writes to 3F7h), and

170h-177h, 376h-377h (excludes writes to 377h).

1: Power management monitors only writes to I/O Port 1F6h and 1F7h.

Partial Secondary Hard Disk Decode. This bit is used to restrict the addresses which are decoded as secondary hard disk

accesses.

0: Power management monitors all reads and writes to I/O Port 170h-177h, 376h-377h (excludes writes to 377h).

1: Power management monitors only writes to I/O Port 176h and 177h.

3:2

Reserved. Must be set to 0.

Mouse on Serial Enable. Mouse is present on a Serial Port.

0: No.

1: Yes.

If a mouse is attached to a serial port (i.e., this bit is set to 1), that port is removed from the serial device list being used to

monitor serial port access for power management purposes and added to the keyboard/mouse decode. This is done

because a mouse, along with the keyboard, is considered an input device and is used only to determine when to blank the

screen.

This bit and bit 0 of this register determine the decode used for the Keyboard/Mouse Idle Timer Count Register (F0 Index

9Eh) as well as the Parallel/Serial Port Idle Timer Count Register (F0 Index 9Ch).

Mouse Port Select. Selects which serial port the mouse is attached to:

0: COM1

1: COM2.

For more information see the description of bit 1 in this register (above).

Index 94h-95h

Suspend Modulation Register (R/W)

Reset Value: 0000h

15:8

Suspend Signal Asserted Counter. This 8-bit counter represents the number of 32 µs intervals that the internal SUSP#

signal is asserted to the GX1 module. Together with bits [7:0], perform the Suspend Modulation function for CPU power

management. The ratio of SUSP# asserted-to-de-asserted sets up an effective (emulated) clock frequency, allowing the

power manager to reduce GX1 module power consumption.

This counter is prematurely reset if an enabled speedup event occurs (i.e., IRQ and video speedups).

7:0

Suspend Signal De-asserted Counter. This 8-bit counter represents the number of 32 µs intervals that the internal SUSP#

signal is de-asserted to the GX1 module. Together with bits [15:8], perform the Suspend Modulation function for CPU power

management. The ratio of SUSP# asserted-to-de-asserted sets up an effective (emulated) clock frequency, allowing the

power manager to reduce GX1 module power consumption.

This counter is prematurely reset if an enabled speedup event occurs (i.e., IRQ and video speedups).

Table 6-29. F0: PCI Header/Bridge Configuration Registers for GPIO and LPC Support (Continued)

Bit

Description

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