IBM 600 Manuale Utente
2. Reset the system microprocessor by writing a 1 to
bit 0.
3. Issue a Halt instruction to the system
microprocessor.
4. Reenable all maskable and nonmaskable interrupts.
If you do not follow this procedure, the results are
unpredictable.
unpredictable.
Note: Whenever possible, use BIOS as an interface to
reset the system microprocessor to the real
mode. For more information about resetting the
system microprocessor, refer to the
mode. For more information about resetting the
system microprocessor, refer to the
IBM Personal
System/2 and Personal Computer BIOS
Interface.
Interface.
System Control Port B (Hex 0061)
Bit definitions for the write and read functions of this port are shown
in the following figures:
in the following figures:
Figure
2-32. System Control Port B (Hex 0061, Write)
Bit
Function
7–4
Reserved
3
Enable channel check
2
Enable PCI SERR#
1
Enable speaker data
0
Timer 2 gate to speaker
Figure
2-33. System Control Port B (Hex 0061, Read)
Bit
Function
7
PCI SERR# (PCI error) status
6
Channel check status
5
Timer 2 output
4
Toggles with each refresh request
3
Enable channel check
2
Enable PCI SERR# (PCI error) check
1
Enable speaker data
0
Timer 2 gate to speaker
Bit 7
If a system board error occurs and the PCI SERR# line is
activated, this bit is set to 1.
activated, this bit is set to 1.
2-30 System Board