    DFI P5BTX-L motherboard BIOS 07/03/98-i430TX-2A59ID4AC-00
    with patch J.2 for AMD K6-2CXT, K6-III, K6-2+ and K6-III+ support,
    and Cyrix MII x4 multiplier support,
    and for IDE HDDs up to 128GB (32GB bugfix).
    03/20/2026
    by Jan Steunebrink

The latest BIOS upgrade from DFI for the P5BTX-L is the 07/03/1998 version.
This BIOS does not support the (mobile) K6-2+/III+ CPUs.
Also the original K6-2CXT and K6-III are not fully supported because this
BIOS doesn't support Write Allocation for the CXT core and doesn't know
speeds above 400 MHz.

To overcome these problems, I have patched the 07/03/98 BIOS to include
proper recognition and handling of the K6-2CXT/-III, and K6-2+/-III+.
I've made the following changes:
- Added detection of the K6-2+, and K6-III+ CPUs
- Added detection of the Cyrix MII when set to x4 multiplier mode
- 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)
  CPU speed support for the K6-2CXT, K6-III, K6-2+ and K6-III+.

In addition I have made a patch to remove the 32GB IDE harddisk limit bug,
and made another patch to remove two additional 64GB limit bugs.
This patched BIOS supports now IDE drives upto 128GB and allows drives upto
640GB to be attached, although the BIOS will then only 'see' the first 128GB.
After booting to a suitable OS (WinXP+SP1 or later, Linux+kernel 2.4.19 or
later) the whole drive upto 640GB can be used, provided all the bootup code
is present in partition(s) below the 128GB boundary.

I also fixed the UDMA mode bug when using ATA/66 and faster IDE drives.
The BIOS now limits the reported transfer 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 Rev.
07/03/98, so you don't have to clear the CMOS if you upgrade from this BIOS.

The filename of the patched BIOS is P5BTXLJ2.BIN and you can flash it with
the flash program you normally use to flash a P5BTX-L BIOS upgrade.
Please take the usual precautions when flashing your BIOS.

Note that, although this patched BIOS has been tested on a P5BTX-L
system without any problems, it is provided "as is" and you use it
at your own risk.

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

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