IBM 560z Manuale Supplementare
System Control Port B (X
'
0061
'
)
Bit definitions for the write and read functions of this port are shown
in the following figures:
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.
(SERR#) was pulsed active.
Bit 6
If set to 1, this bit indicates a channel check has
occurred.
occurred.
Bit 5
If read, this bit indicates the condition of the timer/counter
2 ‘output’ signal.
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.
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