CS5535-UDCF AMD (ADVANCED MICRO DEVICES), CS5535-UDCF Datasheet - Page 369

• Manufacturer Part Number: CS5535-UDCF
• Manufacturer: AMD (ADVANCED MICRO DEVICES)

Specifications of CS5535-UDCF

• Operating Temperature (min): 0C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Lead Free Status / RoHS Status: Compliant

Keyboard Emulation Logic Register Descriptions
6.10.2.5 Port A (KEL_PORTA)
I/O Port
Type
Reset Value
Bit 4 of KELX_CTL (MSR 5140001Fh[4]) is the Port A Enable bit. It must be set to 1 to enable access to this register; other-
wise, Port A accesses are directed to the LPC bus where a Port A register may exist in a SuperI/O device.
:
AMD Geode™ CS5535 Companion Device Data Book
Bit
7:2
1
0
7
Name
RSVD
A20_MASK
SYSR
092h
R/W
00h
6
Description
Reserved. Writes have no effect; reads return 0.
A20 Mask. This bit is necessary for older programs that require Port A Address bit 20
emulation. It requires ASMIs to be enabled in order for software to recognize the chang-
ing of this bit, and subsequent proper emulation of the A20 address bit (see
PORTA_A20_ASMI_EN bit in DIVIL GLD_MSR_SMI, MSR 51400002h[6], for ASMI
enabling details). Anytime this bit is changed an ASMI is generated.
If this bit is 1 and a 0 is written, and ASMI generation is enabled, then proper VSA oper-
ation causes a rollover of address from A[19:0] = all 1s, to A[19:0] = all 0s. Address bit
A20 is 0.
If this bit is 0 and a 1 is written, and ASMI generation is enabled, then no legacy rollover
occurs from address [19:0] = all 1s. The next incremental address is A20 = 1 and
A[19:0] = all 0.
Legacy System Reset. Writing a 1 to this bit causes a system soft reset (INIT) that will
only happen if ASMIs are enabled (see PORTA_INIT_ASMI_EN bit in DIVIL
GLD_MSR_SMI, MSR 51400002h[7], for ASMI enabling details). Writing a 0 to this bit
has no effect. This bit always reads as 0.
5
RSVD
KEL_PORTA Bit Descriptions
KEL_PORTA Register Map
4
3
2
31506B
A20_MASK
1
SYSR
0
369