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Jan Steunebrink's modded BIOS for PCchips M520/A101/etc.

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Sujet du message : Jan Steunebrink's modded BIOS for PCchips M520/A101/etc.
Publié : 27 mars 2021 21:35
contents: M520_J2.BIN, PATCH.TXT
Citation :
PCChips M520 motherboard BIOS Release 1.1A (12/07/98)
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).
by Jan Steunebrink

The latest, and probably final, BIOS upgrade from PCChips for the M520 is
Release 1.1A. 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 properly supported.
To overcome these problems, I have patched the Rel 1.1A BIOS to include proper
recognition and handling of the MII, K6-2CXT, 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)-2+, and K6(tm)-III+ strings
- Extended CPU speed support for the K6-2, K6-III, K6-2+, and K6-III+
to 450MHz (6.0x75).

In addition I have applied Petr Soucek's patch to remove the 32GB IDE harddisk
limit bug, and made another patch to remove an additional 64GB limit bug.
This patch J.2 BIOS supports now IDE drives upto 128GB, provided the harddisks
TYPE and MODE are set on Auto for drives larger than 64GB.
(Note: Due to another bug the BIOS SETUP hangs when manually inserting
HD parameters above 65535MB or when using the IDE HDD Auto Detection
function of the BIOS on drives larger than 64GB. Just set the Harddisks
TYPE and MODE to Auto for any drive above 64GB to avoid this error.)

For all other functions, the patched BIOS is identical to the original Rel.1.1A,
so you don't have to clear the CMOS if you upgrade from this BIOS.

The filename of the patched BIOS is M520_J2.BIN and you can flash it with
the flash program you normally use to flash an M520 BIOS upgrade.
Please take the usual precautions when flashing your BIOS.

Note that, although this patched BIOS has been tested on different M520
systems 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.

E-mail :
I tested it on my PCChips A101 V1.4 and it works perfectly. BIOS itself was modified in 2007, but as Jan told me, there wasn't much user feedback and because of that he didn't publish it on his website. Now, in 2021 I asked him if he still has this BIOS and he sent it to me and I'm very grateful to him.

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