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AMD Geode™ SC1200/SC1201 Processor Data Book 213
Core Logic Module - Bridge, GPIO, and LPC Registers - Function 0
32579B
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
register.
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
7 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.
6 Reserved. Must be set to 1.
5 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.
4 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.
1 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).
0 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