Description Of The Switch Positions S2 (Tty, Bios) - Siemens SIMATIC Box PC 820 Manual

Motherboard
2.8.29

Description of the Switch Positions S2 (TTY, BIOS)

Switch Settings
The following switch settings are for your information only. They are set in the fac-
tory and may not be changed.
x means that this switch is irrelevant for the funtion described.
BIOS Source File
S2 (3)
off Boot EPROM activated (standard setting)
on Boot EPROM not activated (boot module required)
TTY Setting S2
S2 (1)
on on
off x
x off
Setting the Front Side Bus Frequency S2
S2(4)
on 8.25MHz
off 8.25MHz
1)
Frequency is dependent on the processor and is set automatically e.g. 100 MHz for
Pentium III.
2-28
S2 (2)
active TTY interface (standard setting)
TTY transmit loop, isolated from power source
(passive setting)
TTY receive loop, isolated from power source
(passive setting)
ISA Bus Frequency PCI Bus Frequency
33MHz
33MHz
Function
Function
CPU Bus Frequency
66MHz
1)
100MHz
Box PC 820 / PC FI45 V2, Manual
A5E00051531-03