BIOS Updates forum

I have an M535 board with UMC IO chip, flashed with a M520 BIOS with the release date of 12/07/98

ID string =
PC Chips M520 (Rel. 1.1A)
12/07/98-i430VX-2A59GHTBC-00

Is this actually newer than the 10/17/97-i430VX-02271997C-00 on http://wims.rainbow-software.org/index.php?count=-1 ?

The original ID string was 10/16/96-i430X-10031996C-00 I couldn't find any M535 BIOS anywhere, but did find a few things saying the M520 BIOS would work, and it does, except for POST saying it's an M520.

If someone wants this BIOS to do stuff to, I'll be happy to send it. How can I tell if it's the L or S type?

that is the last bios released. It is S-type so if your board still lives you have an S-type bios. Unsure if this has harddisk support >32GB.

Usually you can see this in the release <some date code>S
release <some date code>L on the startup screen.

The patched BIOS does have support for >32GB.

Thanks.

How can I find out if the 1998 BIOS has any improvements (like CPU support) over the patched 1997 BIOS, or if the 1998 BIOS already supports drives over 32gig?

I don't have a 32 to 64 gig drive to test it, but I do have a noisy 13gig Maxtor to check it for the 8gig limit.

I've looked into the M520 12/07/98 BIOS and it seems to have IDE HDD support up to 32GB.
CPU support includes the K6-2 and K6-III up to 400MHz but Write-Allocation support is limited to the K6 and original K6-2. So no WA for the K6-2CXT and K6-III, and the K6-2+ and K6-III+ are not supported at all.

The BIOS is patchable for 128GB and extented AMD support. Let us know what you need!

Jan.

I was going to ask you to do this at one time, but I found out that my Amptron PM 7900 (M520 clone) has a short in the VCore - V I/O circuit...so I cannot power a split-plane CPU.

I even bought a VRM module too.

I'd still be interested in this at some point...if and when I can find the short.

Thanks.

BiosMan wrote: The BIOS is patchable for 128GB and extented AMD support. Let us know what you need!

Jan.

Well, that, of course! There wouldn't happen to be undocumented Vcore settings, eh?

If I could shoehorn a K6-2 450 onto this board, that would give me the board for Box 07 for Retro-LAN at Fandemonium 2008.

The other six PCs I have are a PII 350 (100Mhz bus), K6-2 450 AHX, K6-2 450 AFX, K6-2+ 500, K6-III 450, Duron 900.

My own personal personal computers are an Athlon 64 3500, a Socket 478 Celeron 3.5Ghz, and new just today an Acer Aspire 5315 1.73Ghz Celeron laptop. $348 on a Wal-Mart one day only doorbuster sale. (Vista Home Basic! BLEEAGGHRECH!) Oh, and a crotty olde Tecra 8000 300Mhz PII laptop.

KachiWachi wrote:I was going to ask you to do this at one time, but I found out that my Amptron PM 7900 (M520 clone) has a short in the VCore - V I/O circuit...so I cannot power a split-plane CPU.

Make sure all places that have solder pads for jumpers are actually with a jumper and not hardwired. Might do the trick...

KachiWachi wrote: I even bought a VRM module too.

Any chance of reproducing the circuit layout of that one so one could do a "home-brew" version?

i have several vrm boards. they are all using simple pwm controllers like this:
http://focus.ti.com/lit/ds/symlink/ucc3800.pdf

the circuit is basically the same as this one:
http://focus.ti.com/lit/an/slua185/slua185.pdf

btw. PCChips boards are often using this:
http://www.onsemi.com/pub/Collateral/MC34063A-D.PDF

i could try to make a circuit with the MC34063A, too..if someone is interested.

Just as an exercise alone that would be fun I think. The main thing is the VRM socket layout unless that is completely standardized?

@edwin -

The VCore and V I/O planes are shorted together internally...so that pretty much kills using a VRM untill I can separate them (somehow).

I bought an HP VRM (switching type) that will run a 233MMX...but I indended to modify it to run other CPU's (resistor selection).

Thanks.

VRM layout is standardized:

http://www.tec.ufl.edu/~jhavar/pentium_ ... rboard.pdf

@KachiWachi: can you send a picture of the mainboard? maybe we can find out how to separate the planes.

you can btw. request free samples of the UCC3803D at:
http://focus.ti.com/docs/prod/folders/p ... ml#samples

@cp -

How would a picture help?

The only place VCore is *supposed* to go is to the CPU.

On these boards, four jumpers are inserted into the VRM slot when a single plane CPU is installed. Pulling the jumpers separates the planes from +3.3V so that the VRM can do its thing.

When I pull the jumpers, the planes are not isolated from each other (ohm check)...hence a short *must* be present internally in the motherboard...or a solder splash exists under the CPU socket (which I cannot see).

(Note - CPU is removed for the ohm check.)

is the board still running if you remove the jumpers?

Yes...if you mean remove only one set (since something must be connected to the 3.3V source ).

Edit - Clarification.