Intel 281786-002 User Manual
Advanced/ZP Technical Product Summary
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Page 16
PROCESSOR VOLTAGE REGULATION - SWITCH 2
Sets the output of the on-board voltage regulator. The switch settings are OFF = VR, and ON = VRE. The VR voltage
specification requires a voltage range of 3.3-3.465 Volts DC, while the VRE specification requires a voltage range of 3.45-
3.6V. Pentium processors currently available that do not require the VRE voltage specification should use the VR setting.
When upgrading your CPU be sure to consult the documentation for the processor voltage requirements before setting this
switch, as an incorrect setting may damage the processor. The default position is with the switch set for VR (off).
specification requires a voltage range of 3.3-3.465 Volts DC, while the VRE specification requires a voltage range of 3.45-
3.6V. Pentium processors currently available that do not require the VRE voltage specification should use the VR setting.
When upgrading your CPU be sure to consult the documentation for the processor voltage requirements before setting this
switch, as an incorrect setting may damage the processor. The default position is with the switch set for VR (off).
ISA BUS SPEED - SWITCH 1
Sets the ISA bus speed to either 1/4 or 1/3 of the PCI bus speed to best maximize system performance for 75, 90, 100 or
120 MHz processor speeds. When SW1=ON the ISA bus speed will be 1/4 of the PCI bus speed and when SW1=OFF the
ISA bus speed will be 1/3 the PCI bus speed. The ISA bus speed is derived from the PCI bus speed which is derived from
the external processor clock frequency. The position of SW1 will set the ISA bus speed to either Compatible or Enhanced
for 90 MHz, 100 MHz, and 120 MHz processors and will leave the ISA bus speed Compatible for 75 MHz processor speed.
For 90 MHz, 100 MHz, and 120 MHz processor speeds, if SW1 is set to Compatible (SW1=ON), the speed will fall within
the limits defined by the IBM AT Technical Reference (6-8.33 MHz). If set to Enhanced (SW1=OFF), the speed will be
greater than the maximum defined by the IBM AT Technical Reference manual. SW1 can be set to either position when a
75 MHz processor speed is used for maximum ISA bus performance. Modern ISA cards can operate with the enhanced
speeds, however some older cards can experience difficulties. The actual value of the Bus Clock when set to Compatible or
Enhanced is dependent upon the setting of the external processor frequency. The following table describes the ISA bus
speeds for the 75 MHz, 90 MHz, 100 MHz, and 120 MHz processor speeds.
120 MHz processor speeds. When SW1=ON the ISA bus speed will be 1/4 of the PCI bus speed and when SW1=OFF the
ISA bus speed will be 1/3 the PCI bus speed. The ISA bus speed is derived from the PCI bus speed which is derived from
the external processor clock frequency. The position of SW1 will set the ISA bus speed to either Compatible or Enhanced
for 90 MHz, 100 MHz, and 120 MHz processors and will leave the ISA bus speed Compatible for 75 MHz processor speed.
For 90 MHz, 100 MHz, and 120 MHz processor speeds, if SW1 is set to Compatible (SW1=ON), the speed will fall within
the limits defined by the IBM AT Technical Reference (6-8.33 MHz). If set to Enhanced (SW1=OFF), the speed will be
greater than the maximum defined by the IBM AT Technical Reference manual. SW1 can be set to either position when a
75 MHz processor speed is used for maximum ISA bus performance. Modern ISA cards can operate with the enhanced
speeds, however some older cards can experience difficulties. The actual value of the Bus Clock when set to Compatible or
Enhanced is dependent upon the setting of the external processor frequency. The following table describes the ISA bus
speeds for the 75 MHz, 90 MHz, 100 MHz, and 120 MHz processor speeds.
Internal Processor Frequency
PCI bus Frequency
SW1=OFF (1/3)
SW1=ON (1/4)
75 MHz
25 MHz
8.33 MHz
8.33 MHz
90 MHz
30 MHz
10.0 MHz
7.50 MHz
100 MHz
33 MHz
11.0 MHz
8.33 MHz
120 MHz
30 MHz
10.0 MHz
7.50 MHz
Table B-2. ISA Bus Speed Switch Settings
RECOVERY BOOT ENABLE - J1K1
This switch allows the system to boot in the event the system BIOS has been corrupted by moving the jumper from the
default position of 1-2 to the 2-3 position. A recovery disk must be in drive A while booting up with this jumper set to 2-3.
Once the recovery is complete the jumper should be move back to pins 1-2, and the system rebooted.
default position of 1-2 to the 2-3 position. A recovery disk must be in drive A while booting up with this jumper set to 2-3.
Once the recovery is complete the jumper should be move back to pins 1-2, and the system rebooted.