Filter
Top Products
Advanced/RH Technical Product Specification •• Page 26
CPU CONFIGURATION - JUMPER BLOCK J4L1(C&D)
These allow the motherboard to be switched between different speeds of the Pentium processor. These jumpers
also affect the PCI and ISA clock speeds according to the following table:
CPU Freq.
(MHz)
Host Bus
Freq. (MHz)
Host Bus
pins J4L1C
1-3
Host Bus
pins J4L1C
4-6 CLK Ratio
Clk Ratio
pins J4L1D
1-3
Clk Ratio
pins J4L1D
4-6
PCI Freq.
(MHz)
166 66 1-2 5-6 5/2 2-3
5-6
33
150 60 2-3 4-5 5/2 2-3
5-6
30
133 66 1-2 5-6 2 2-3
4-5
33
120 60 2-3 4-5 2 2-3
4-5
30
100 66 1-2 5-6 3/2 1-2
4-5
33
90 60 2-3 4-5 3/2 1-2
4-5
30
75 50 2-3 5-6 3/2 1-2
4-5
25
reserved - 1-2 4-5 - X
X
-
Table B-2. CPU/SYSTEM speed settings (* default setting)
The ISA clock is derived from the PCI bus clock. The BIOS automatically sets the ISA clock speed to one fourth of
the PCI frequency.
PCI Frequency ISA clock speed
25 MHz 6.25 MHz
30 MHz 7.5 MHz
33 MHz 8.25 MHz
Table B-3. ISA clock settings set by the BIOS based on PCI Clk Speed
CMOS -J4L1 A PINS 4-6
Allows CMOS settings to be reset to default values by moving the jumper from pins 4-5 to pins 5-6 and turning the
system on. When the system reports “NVRAM cleared by jumper”, the system can be turned off and the jumper
should be returned to the 4-5 position to restore normal operation. This procedure should be done whenever the
system BIOS is updated. Default is for this jumper to be on pins 4-5.
PSWD -J4L1 A PINS 1-3
Allows system password to be cleared by moving the jumper from pins 1-2 to pins 2-3 and turning the system on.
The system should then be turned off and the jumper should be returned to the 1-2 position to restore normal
operation. This procedure should only be done if the user password has been forgotten. The password function is
effectively disabled if this jumper is in the 2-3 position. Default is for the password to be enabled (1-2 position).
SETUP - J4L1 B PINS 1-3
Allows access to CMOS Setup utility to be disabled by moving this jumper from the 1-2 position to the 2-3
position. Default is for access to setup to be enabled (1-2 position).
RISER - J4G1
The riser jumper block allows routing of an extra IRQ and ID select to the riser card for an additional PCI slot to
support a maximum of 3 PCI slots on a riser. Default is set for 2 PCI slots on the riser card (1-2 position and 4-5
position).