IBM x 340 Series, Hardware Maintenance Manual

Page: 51 / 188

Installing options
43
c
1
d
System board switch block (SW1)
c
2
d
Boot block jumper (J37)
System board jumper blocks
Any jumper blocks on the system board that are not shown in the illustration are
reserved. For normal operation of the system, no jumpers should be installed on any
of the jumper blocks. See “Recovering BIOS” on page 16 for information about the
boot block jumper.
System board switch block
The switch block contains microswitches 1-8. As shown in this illustration, switch 8 is
at the top of the switch block and switch 1 is at the bottom.
The following table describes each switch.
Table 7. Switches 1-8.
Switch number Description
1- 4 Microprocessor speed setting. See Table 8 on page 44.
5 Power-on override.
When On, overrides the power-on switch and forces power-on mode. The system will always
boot without the use of the power-on switch. The default setting is Off (disabled).
6 Clock frequency selection.
When On, sets the host bus speed to 100 MHz. When Off, the host bus speed is 133 MHz. The
default setting is Off.
7 Reserved. The default setting is Off.