How do you trim a BIOS file?

[survivalbloke]

I downloaded a BIOS file from Lenovo and once I extracted the actual BIOS from the executable, it is 16MB in size, but my IC(Winbond 25Q80DV) is only 8MB in capacity. I have read you can trim the BIOS file with a hex editor but I can't find any instructions on specifically what you will remove.

[mon2]

Often there are 2 bioses on the logic board. A high density (main bios) and a low density (EC controller firmware). It appears that you are physically referencing the EC controller device on the logic board and attempting to reflash it with the main bios firmware. Keep searching for a higher density bios chip on the board for the proper match.

[survivalbloke]

Thanks - will do!

[survivalbloke]

Often there are 2 bioses on the logic board. A high density (main bios) and a low density (EC controller firmware). It appears that you are physically referencing the EC controller device on the logic board and attempting to reflash it with the main bios firmware. Keep searching for a higher density bios chip on the board for the proper match.

OK, you were absolutely correct. So I located the other Winbond chip, which was 128Mb. But when I tried to flash it, I still get the size error.
BIOS file is 17,650KB.
https://www.dropbox.com/scl/fi/op2cc...453houv9g&dl=0

[SMDFlea]

OK, you were absolutely correct. So I located the other Winbond chip, which was 128Mb. But when I tried to flash it, I still get the size error.
BIOS file is 17,650KB.
https://www.dropbox.com/scl/fi/op2cc...453houv9g&dl=0

Didn`t you make a backup first ? .What model is it for,and whats the serial number https://www.badcaps.net/forum/troubl...before-posting

The file needs editing with a hex editor to get the 16MB bios image

[survivalbloke]

SMDFlea Mistakes were made, and this has been a tremendous learning experience as I had no idea the EC had its own, separate firmware chip. To make a very long story short, before seeing your post, I found a program to cut the bios down and I flashed it to the bios chip. However, I screwed up the EC firmware on that smaller chip. So, now it is not doing anything on power button press. Is there a way to get the EC firmware so I can properly re-flash that chip?

Device: Laptop
Brand: Lenovo
SN: PF259ZEJ
Model: Yoga C740-15IML
Board: FYG50 NM-C433 Rev 1.0

[SMDFlea]

SMDFlea Mistakes were made, and this has been a tremendous learning experience as I had no idea the EC had its own, separate firmware chip. To make a very long story short, before seeing your post, I found a program to cut the bios down and I flashed it to the bios chip. However, I screwed up the EC firmware on that smaller chip. So, now it is not doing anything on power button press. Is there a way to get the EC firmware so I can properly re-flash that chip?

Device: Laptop
Brand: Lenovo
SN: PF259ZEJ
Model: Yoga C740-15IML
Board: FYG50 NM-C433 Rev 1.0

The EC chip is ITE8586E i think. It will have internal flash. So the chip you overwrote ? , is for some other firmware, not sure which one could be PD firmware .Is U4503 silkscreened next to that chip ? https://www.badcaps.net/forum/troubl...ntroller-firmw

You`re not the first one to flash the wrong chip,and you won`t be the last

[survivalbloke]

SMDFlea Yeah, U4503! Wow, I cannot believe someone had that dump. I'll flash it today or tomorrow and report back. Thanks!

[SMDFlea]

SMDFlea Yeah, U4503! Wow, I cannot believe someone had that dump. I'll flash it today or tomorrow and report back. Thanks!

It was a good guess. When you find the 16MB chip (25Q128 or similar) make a backup and post it here,don`t erase that chip yet, there`s DMI info in that, the windows key and possibly other important stuff that needs copying from it to the new bios

[survivalbloke]

It was a good guess. When you find the 16MB chip (25Q128 or similar) make a backup and post it here,don`t erase that chip yet, there`s DMI info in that, the windows key and possibly other important stuff that needs copying from it to the new bios

Man, I have so much to learn. So then, one could not simply buy a new chip from ebay and flash the BIOS from the lenovo site onto it? This is a very important question for my learning experience.

Well, I'm not sure what the problem is now. I went ahead and flashed that chip(U4503) but the laptop is not taking any current, and I get nothing when pressing the power button. I do have 12V present at the battery circuit coil. I've also got 3.3v present at the U4503 chip I just flashed. However, where I believe I should have 20v, I only have 13.74v.

Let me extrapolate the story of this laptop which might shine light somewhere. It was a customer's laptop and they bought a new one, donating this one to me(happens all the time). Initially the issue was that all voltages were present, and pressing the power button would power up the device, but I had no video and no caps lock. CPU was warm, fans running, seemed very normal and alive. I just took a guess and figured it must be a BIOS problem - maybe a ME region issue(even though I don't quite understand that), etc. I couldn't find anyone with a BIOS for it and I also hadn't learned how to extract a BIOS from a Lenovo executable so I bought a "parts only" board from Ebay. Much to my surprise, the parts board actually powered up the laptop and I had video! The trouble is that the parts board had a broken CPU heatsink mount, so I decided to swap out not only the 16MB chip, but also that other firmware chip - the U4503 to the original board. It powered up just the same, so I went ahead and installed Windows but for the life of me I could not get a sound driver and the intel ME engine management driver to take. Lenovo's tool to detect my product was detecting the wrong serial number so I knew something is wrong with the chip swap. That's when all of this madness began.

So now I have 2x BIOS chips(16MB) neither of which I know which board they go to, and I've got 1x U4503 firmware chip, flashed with the file from the link you posted. I only have one of these chips because the chip which was on the original board, a winbond, would not read in my CH341a so I think something is wrong with it.

If I backup and post an image of both BIOS chips and the firmware chip here in the thread, is there any chance you could look at them and know which is which, etc..???

[survivalbloke]

Here is what I have...

[hoaca388]

Here is what I have...

Laptop Yoga C740-15IML (Lenovo) - Loại 81TD

[survivalbloke]

Laptop Yoga C740-15IML (Lenovo) - Loại 81TD

What is this file?

[hoaca388]

What is this file?

Bios file.