    Gigabyte GA-586ATX motherboard BIOS V2.0 (07/20/1998)
    with patch J.2 for Cx MII, AMD K6-2CXT, K6-III, K6-2+ and K6-III+ support,
    and for IDE HDDs up to 128GB (32GB bugfix).
    02/09/2024
    by Jan Steunebrink

The latest, and probably final, BIOS upgrade from Gigabyte for the 586ATX is the
07/20/1998 Version 2.0. This BIOS does not support the (mobile) K6-2+/III+ CPUs.
Also the original K6-2CXT / K6-III, and Cyrix MII CPUs with 4.0x multiplier,
are not (fully) supported.

To overcome these problems, I have patched the 07/20/1998 BIOS to include
proper recognition and handling of the MII, K6-2/CXT, K6-III, and K6-2+/III+.
I've made the following changes:
- Added detection of the Cyrix MII when set to 4.0x multiplier
- Added detection of the K6-2+, and K6-III+ CPUs
- Expanded the K6 Write Allocation feature to work also on all K6-2/III CPUs
  with the CXT core and enabled this feature for the K6-2+ and K6-III+ as well
- Expanded the CPU Type display routine for correct display of the AMD-
  K6(tm)-III, K6(tm)-2+, and K6(tm)-III+ strings
- Added 6.0x83 (500MHz), 5.5x83 (458MHz), 6.0x75 (450MHz), and 5.5x75 (412MHz)
  support for the K6-2CXT, K6-III, K6-2+ and K6-III+.
- Set the Setup Defaults for the Video and System BIOS Cacheable options to
  Disabled. The K6-III and K6-2+/III+ need this setting to run properly.

In addition I have made a patch to remove the 32GB harddisk limit bug, and
made another patch to remove two additional 64GB limit bugs.
This patch J.2 BIOS supports now IDE drives upto 128GB.

I also fixed the UDMA mode bug when using ATA/66 and faster IDE drives.
The BIOS now limits the reported tranfer speed to UDMA mode 2 on these faster
drives, the maximum for this chipset.
This allows Win98 to enable DMA mode correctly.

For all other functions, the patched BIOS is identical to the original 07/20/98,
so you don't have to clear the CMOS if you upgrade from this BIOS.

The filename of the patched BIOS is 5ATX_J2.BIN and you can flash it with
the flash program you normally use to flash a GA-586ATX BIOS upgrade.
Please take the usual precautions when flashing your BIOS.

Note that, although this patched BIOS has been tested on different GA-586ATX
systems without any problems, it is provided "as is" and you use it
at your own risk.
CAUTION: Do NOT use the CPU Auto Voltage DIP-switch setting on any K6 series
CPU. The Auto Voltage setting is for Intel, Cyrix, and AMD K5 CPUs only!
So for K6, K6-2, K6-III, K6-2+, and K6-III+, set SW 4,5,6,7 manually for the
required 2.0V-2.4V Vcore voltage.

I like to thank everybody who participated in testing this BIOS.
Jan.

Homepage: http://www.steunebrink.info/
E-mail  : J.Steunebrink@net.HCC.nl
