Dell Precision 420 - Manual (Page 118)

Mode
You can set this option to PS/2 (the default) , EPP, ECP, AT, or Off to disable the port.
Set this option according to the type of peripheral device connected to the parallel port. To determine the correct mode to use, see the
documentation that came with the device.
I/O Address
This option determines the I/O address used by the parallel port and appears except when Mode is set to Off. You can set I/O Address to 378h
(the default), 278h, or 3BCh.
DMA Channel
This option determines the direct memory access (DMA) channel used by the parallel port and appears only when Mode is set to ECP. The
available options are DMA 1, DMA 3, and Off.
IDE Drive Interface
IDE Drive Interface enables or disables the system's enhanced integrated drive electronics (EIDE) hard-disk drive interface.
With Auto (the default) selected, the system turns off the EIDE interface when necessary to accommodate an EIDE controller card installed in an
expansion slot.
As part of the boot routine, the system first checks for a primary hard-disk drive controller card installed in an expansion slot. If no card is found, the
system enables the EIDE interface to use IRQ14 and IRQ15.
If a primary controller is detected on the expansion bus, the EIDE interface is disabled.
Selecting Off disables the integrated EIDE interface.
Diskette Interface
Diskette Interface controls the operation of the system's integrated diskette drive controller.
With Auto (the default) selected, the system turns off the integrated diskette drive controller when necessary to accommodate a controller card
installed in an expansion slot.
With Read Only selected, nothing can be written to any diskette drives and tape drives using the system's integrated diskette/tape drive controller.
(The system can still read from the drives.) When Read Only is selected, Auto (whereby the system turns off the integrated diskette drive
controller as necessary) is also in effect.
Selecting Off turns off the integrated diskette/tape drive controller; this setting is used primarily for troubleshooting purposes.
USB Emulation
USB Emulation determines whether the system basic input/output system (BIOS) controls Universal Serial Bus (USB) keyboards and mice.
When On is selected, the system BIOS controls USB keyboards and mice until a USB driver is loaded by the operating system. When Off is
selected (the default), the system BIOS does not control USB keyboards and mice, though they are functional during the boot routine. Set USB
Emulation to Off if you are using a Personal System/2 (PS/2)-compatible keyboard and mouse. You cannot use the USB ports with PS/2
peripherals.
PC Speaker
PC Speaker determines whether the legacy PC sound is On (the default) or Off. A change to this option takes effect immediately (rebooting the
system is not required).
Video DAC Snoop
Video DAC Snoop lets you correct video problems that may occur with the use of some video expansion cards. The default is Off. If you are using
a video expansion card and problems such as incorrect colors or blank windows occur, set Video DAC Snoop to On.
SCSI Controllers
SCSI Controllers turns the integrated SCSI channels On or Off (the default).
Keyboard NumLock
Keyboard NumLock determines whether your system boots with the Num Lock mode activated on 101- or 102-key keyboards (it does not apply
NOTE: This option enables or disables only the legacy PC sound. It does not turn the internal monophonic speaker on or off. Basic
input/output system (BIOS) beep codes are always audible regardless of this option's setting.