Intel 281809-003 CPU CONFIGURATION - JUMPER BLOCK J4L1C&D, CMOS -J4L1A PINS, PSWD -J4L1A PINS

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)

166

150

133

120

100

90

75

reserved

Host Bus

Freq. (MHz)

66

60

66

60

66

60

50

-

Host Bus

pins J4L1C

1-3

1-2

2-3

1-2

2-3

1-2

2-3

2-3

1-2

Host Bus

pins J4L1C

4-6

5-6

4-5

5-6

4-5

5-6

4-5

5-6

4-5

CLK Ratio

5/2

5/2

2

2

3/2

3/2

3/2

-

Clk Ratio pins J4L1D 1-3

2-3

2-3

2-3

2-3

1-2

1-2

1-2

X

Clk Ratio pins J4L1D 4-6

5-6

5-6

4-5

4-5

4-5

4-5

4-5

X

PCI Freq.

(MHz)

33

30

33

30

33

30

25

-

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).

Advanced/RH Technical Product Specification ∙ Page 26