Chapter 16: System switches, user switch, BIOS update, system
functions, CPU speed, CPU fan and LEDs
System switches
Various system function options are selected with Switch 4.
The “S” switch selects whether the card boots from user defined parameters
(defined in the Setup Programs chapter), or the BIOS defaults. Setting this switch
Off allows the user to return to factory programmed defaults.
The “X” switch enables or disables the BIOS extension area. The default is enabled,
which uses the INT17 calls..
The “V” switch enables or disables the on-card video, allowing an external video
card, or the serial console to be used.
The “U” switch is user defined and can be used for program control.
The “R” switch, when set to Off, allows the BIOS to be reinstalled from a remote
system over a serial console connection.
Table 16
−
1 System
configuration switches, Switch 4
System configuration switches, Switch 4
Label Description
Position
S
System parameters option switch:
1
On = enable User Setup options*
Off = enable BIOS Setup default
2
X
BIOS extension enable
On = enable extended BIOS*
allows use of INT17 calls without
loading I17HNDLER.EXE
Off = disables extended BIOS
frees location D8000 - DFFFF
V Video
switch:
3
On = enable on-card video*
Off = disable on-card video
U1
User switch 1, default On*
4
R
BIOS recovery switch:
5
On = normal BIOS operation*
Off = allows new BIOS to be installed
* = default
System switch
The system switch is position 1. When this switch is On the system boots using the
parameters stored in Setup. When this switch is Off the system boots using the
factory defaults for all parameters in Setup. Note that if you must set the system
switch Off to recover your system, the user-defined parameters in Setup will not be
changed unless you enter Setup, make the changes, and exit saving changes.
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