24
2 System Board
Devices on the ISA Bus
System Board Switches and Jumpers
One of the
jumpers
(J7) and two of the
system board switches
(SW2-1 and
SW2-2) set the frequency of the Processor-Local bus, and the ratio of
processor-frequency to Processor-Local-bus-frequency, as summarized on
page 13. The others (whose locations are shown on page 10) set the
configuration for the computer, as summarized in the table below.
By setting switch SW1-2 in the
Closed
position, not only is the
configuration data cleared (in the CMOS memory and the Serial EEPROM),
but also all the Plug-and-Play data that had been saved in the Serial
EEPROM. However, the serial number, the tattooing string, the date and the
time are each retained.
By setting jumper JP4 in its default position, the Power-On Space-Bar
function is enabled. Note, though, that it must
also
be enabled in the
Power-On Space-Bar
field of the Power Menu in the
Setup
program.
Turning the computer on, with jumper J15 removed, clears the product
identification field in the BIOS, and causes the computer to prompt for the
new information. By identifying the product correctly (after installing a new
system board, for example), the BIOS is able to tailor itself for the particular
product, and to enable the appropriate features.
Switch or Jumper
Meaning
Default Setting
SW1
SW1-1: BIOS flash
OFF = enable
ON = disable
OFF
SW1-2: CMOS
OFF = normal
ON = clear
OFF
SW1-3: password
OFF = normal
ON = clear
OFF
JP4
Keyboard power-on
jumper on = enable
no jumper = disable
jumper on
J6
Cache memory type
2-3 = synchronous
1-2 = asynchronous
2-3
J15
Serial EEPROM flag
jumper on = normal
no jumper = clear (reserved for use by HP)
jumper on
