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©2008 Advanced Micro Devices, Inc.
SMBus Module and ACPI Block (Device 20, Function 0)
AMD SB600 Register Reference Manual Proprietary Page 129
IntrCntrl1Reg2- RW – 8 bits - [IO_Reg: 21h]
Field Name Bits Default Description
IntrCntrl1Reg2 7:0 00h IRQ0 – IRQ7:
Read IMR
Write ICW2, ICW3, ICW4, OCW1
IntrCntrl1Reg2 register
IMCR_Index- RW – 8 bits - [IO_Reg: 22h]
Field Name Bits Default Description
IMCR_Index 7:0 00h The IMCR is supported by two read/writeable IO ports 22/23h;
which are used as index and data port respectively. The
actual IMCR register is located at index 70h.
IMCR_Index register
IMCR_Data- RW – 8 bits - [IO_Reg: 23h]
Field Name Bits Default Description
IMCR_Data 7:0 00h The IMCR is supported by two read/writeable IO ports 22/23h;
which are used as index and data port respectively. The
actual IMCR register is located at index 70h and it is at bit 0.
The actual IMCR bit can only be accessed when bit port 22 is
set to 70h. Default value of IMCR is 0.
IMCR_Data register
TimerCh0- RW – 8 bits - [IO_Reg: 40h]
Field Name Bits Default Description
TimerCh0 7:0 00h 8254 Timer 1 – Counter 0 Data Port
This timer is known as the System Clock timer and it is always
on. It is clocked internally by OSC/12 (1.19318MHz), and
asserts IRQ0 every time the timer rolls over. This timer is
used for time-of-day, diskette time-out, and other system
timing functions.
TimerCh0 register
TimerCh1- RW – 8 bits - [IO_Reg: 41h]
Field Name Bits Default Description
TimerCh1 7:0 00h 8254 Timer 1 – Counter 1 Data Port
This timer is normally used for ISA refresh cycles and is also
clocked by OSC/12 (1.19818MHz). Since this refresh function
is no longer needed (we don't have an external ISA bus), it
can be used as a general purpose timing function.
TimerCh1 register
TimerCh2- RW – 8 bits - [IO_Reg: 42h]
Field Name Bits Default Description
TimerCh2 7:0 00h 8254 Timer 1 - Counter 2 Data Port
This is the speaker tone generator and is enabled by IO port
61H. It is clocked by OSC/12 (1.19318MHz) and directly
drives the output SPKR that goes to a speaker.
TimerCh2 register