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Help locating bios for this motherboard M748MR Rev:1.3

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First post, by vico

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I have this motherboard M748MR Rev:1.3 that is giving me some problems, the boot is very slow and apparently it is because the disk and the cdrom take a long time to be recognized and lately the disk is not recognized and gives an error: "sec master hdd error", sometimes also the serial mouse is not recognized. Apparently these issues are caused by a faulty bios.

I have found the following BIOS but an error is produced when trying to program it into the chip.
https://www.elhvb.com/mboards/pcchips/686_M7x … 702S_2M_AMI.zip

Please help me find a working bios update or give me hints on how to program it correctly.

I am attaching images and a backup of the apparently defective BIOS.

Attachments

  • Error.jpg
    Filename
    Error.jpg
    File size
    103.1 KiB
    Views
    432 views
    File license
    Public domain
  • Filename
    M748MR Rev1.3.zip
    File size
    155.85 KiB
    Downloads
    32 downloads
    File license
    Public domain
  • AE29F2008-12.jpg
    Filename
    AE29F2008-12.jpg
    File size
    766.56 KiB
    Views
    432 views
    File license
    Public domain
  • M748MR Rev1.3.jpg
    Filename
    M748MR Rev1.3.jpg
    File size
    1.38 MiB
    Views
    432 views
    File license
    Public domain

Reply 1 of 5, by zyga64

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Do you have another 2MBit (256kB) flash chips ? It does not necessarily have to be AE29F2008. Looks like your BIOS chip is defective 🙁

1) VLSI SCAMP /286@20 /4M /CL-GD5422 /CMI8330
2) i420EX /486DX33 /16M /TGUI9440 /GUS+ALS100+MT32PI
3) i430FX /K6-2@400 /64M /Rage Pro PCI /ES1370+YMF718
4) i440BX /P!!!750 /256M /MX440 /SBLive!
5) iB75 /3470s /4G /HD7750 /HDA

Reply 3 of 5, by vico

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zyga64 wrote on 2023-07-28, 18:07:

Do you have another 2MBit (256kB) flash chips ? It does not necessarily have to be AE29F2008. Looks like your BIOS chip is defective 🙁

Maybe I could buy one but besides being a 2MBit DIP-32, what other aspects should I consider when choosing it?

Reply 4 of 5, by zyga64

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It should be TTL compatible (5V) - not low voltage version.
In my box of 2MBit BIOS chips from old/broken motherboards I have: Winbond W49F002A, w49F002U, SyncMos F29C51002T, SST 39SF020, EON EN29F002 and PMC PM29F002T. Sometimes also location of boot-block is important (top or bottom of flash), but anyway - it is worth to try.
Try to find datasheets of few of those, and check if pinout is the same (to be 100% sure). Even if your TL866 doesn't support some of them there is big chance that with Uniflash 2.0 from here https://soggi.org/motherboards/bios-update-fl … h-utilities.htm you'll be able to hotflash it. I have done it many times successfully.

1) VLSI SCAMP /286@20 /4M /CL-GD5422 /CMI8330
2) i420EX /486DX33 /16M /TGUI9440 /GUS+ALS100+MT32PI
3) i430FX /K6-2@400 /64M /Rage Pro PCI /ES1370+YMF718
4) i440BX /P!!!750 /256M /MX440 /SBLive!
5) iB75 /3470s /4G /HD7750 /HDA

Reply 5 of 5, by Repo Man11

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Check and see if this BIOS is the same one on the Retro Web: https://web.archive.org/web/20061020193316fw_ … d-bios.asp#M748

"I'd rather be rich than stupid" - Jack Handey

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