Dell OptiPlex System BIOS, A20

The following problems in the A19 BIOS were corrected to generate the A20 BIOS:

1. Add support for autoshutdown call for win95 and NT.
2.Properly disable cache if no l2 installed.
3.Make beep code for no memory 1-3-2.
4.Remove 3f6/3f7 from floppy resources.
5.Fix incorrect BASE address stored in on-board S3 configuration space.
6.Assign IRQ's by slot, not function.
7.Support 16-bit IO arbitration, if no 10-bit IO present.
8.Deactivate iorangechk in PNPISA cards.
9.Allow port 102 to be used by PNPISA device.
10.Remove 3BF from the VGA resource table.
11.Use IRQ 15 last when searching for free IRQs for PCI.
12.Turn off S3 PCI disconnect.
13.Allow IRQ 12 use if mouse disabled.
14.Disable bus-master bit in IDE registers when onboard IDE disabled.
15.Fix possible bad year when auto-power-on is enabled.
16.Put 764/765 into bad_dac_snoop_table (force dac snoop off).
17.Allow dac snoop enable for onboard vga when feature connector on.
18.Allow use of 'non-2k multiple' ISA option roms (new ibm TR card).
19.Make copyright notice say 1997.


Version A20, A20



Release date

15 Aug 2000

Last Updated

03 Nov 2011


Available formats

File Format:Hard-Drive
File Name:GX_A20.EXE
Download Type:HTTP
File Size: 124 KB
Format Description:This file contains a compressed (or zipped) set of files. Download the file to a folder on your hard drive, and then run (double-click) it to unzip the set of files. Follow the instructions to complete the installation.
To ensure the integrity of your download, please verify the checksum value.
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Applies to
OptiPlex System BIOS
Warning: Do not turn off your computer or disconnect from your power source while updating the BIOS or you may harm your computer. During the update, your computer will restart and you will briefly see a black screen.

This driver has been tested by both the independent software vendor (ISV) and Dell on the operating systems, graphics cards, and application supported by your device to ensure maximum compatibility and performance. Details

Dell recommends the customer review specifics about the update to determine if it applies to your system. The update contains changes that impact only certain configurations, or provides new features that may/may not apply to your environment.