Lenovo ThinkPad 600E Technical Reference Manual for the ThinkPad 600 - Page 41

RT/CMOS Address and NMI Mask Register Hex 0070, Attention, Bit 7, Bits 6-0

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RT/CMOS Address and NMI Mask Register (Hex 0070) The NMI mask register is used with the RT/CMOS data register (hex 0071) to read from and write to the RT/CMOS RAM bytes. Attention The operation following a write to hex 0070 should access hex 0071; otherwise, intermittent failures of the RT/CMOS RAM can occur. Bit Function 7 NMI mask 6-0 RT/CMOS RAM address Figure 2-14. RT/CMOS Address and NMI Mask Register (Hex 0070) Bit 7 Bits 6-0 When this write-only bit is set to 1, the NMI is masked (disabled). This bit is set to 1 by a power-on reset. These bits are used to select RT/CMOS RAM addresses. RT/CMOS Data Register (Hex 0071) The RT/CMOS data register is used with the RT/CMOS address and NMI mask register (hex 0070) to read from and write to the RT/CMOS RAM bytes. Bit Function 7-0 RT/CMOS data Figure 2-15. RT/CMOS Data Register (Hex 0071) System Board 2-19

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RT/CMOS Address and NMI Mask Register (Hex 0070)
The NMI mask register is used with the RT/CMOS data register (hex
0071) to read from and write to the RT/CMOS RAM bytes.
Attention
The operation following a write to hex 0070 should access hex 0071;
otherwise, intermittent failures of the RT/CMOS RAM can occur.
Figure
2-14.
RT/CMOS Address and NMI Mask Register (Hex 0070)
Bit
Function
7
NMI mask
6–0
RT/CMOS RAM address
Bit 7
When this write-only bit is set to 1, the NMI is masked
(disabled).
This bit is set to 1 by a power-on reset.
Bits 6–0
These bits are used to select RT/CMOS RAM
addresses.
RT/CMOS Data Register (Hex 0071)
The RT/CMOS data register is used with the RT/CMOS address and
NMI mask register (hex 0070) to read from and write to the
RT/CMOS RAM bytes.
Figure
2-15.
RT/CMOS Data Register (Hex 0071)
Bit
Function
7–0
RT/CMOS data
System Board
2-19