IBM ThinkPad 560Z, Дополнительное руководство

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System Control Port B (X ' 0061 ' )
Bit definitions for the write and read functions of this port are shown
in the following figures:
Figure 2-30. System Control Port B (X
'
0061
'
, Write)
Bit Function
7–4 Reserved
3 Reserved (should be 0)
2 Enable parity check
1 Enable speaker data
0 Timer 2 gate to speaker
Figure 2-31. System Control Port B (X ' 0061 ' , Read)
Bit Function
7 Parity check
6 Channel check
5 Timer 2 output
4 Toggles with each refresh request
3 Reserved
2 Enable parity check
1 Enable speaker data
0 Timer 2 gate to speaker
Bit 7 If set to 1, this bit indicates that the PCI system error
(SERR#) was pulsed active.
Bit 6 If set to 1, this bit indicates a channel check has
occurred.
Bit 5 If read, this bit indicates the condition of the timer/counter
2 ‘output’ signal.
Bit 4 If read, this bit toggles for each refresh request.
Bit 3 Reserved.
Bit 2 If set to 0, this bit enables the PCI system error (SERR#).
This bit is set to 1 during a power-on reset.
Bit 1 If set to 1, this bit enables the speaker data.
Bit 0 If set to 1, this bit enables the timer 2 gate.
2-28 ThinkPad 560Z System Board