What's the easiest way to read/write to my laptops bios chip? - Page 1
Forum section: electronics / beginners

author: Hentrox
author_rank: Newbie
timestamp: February 12, 2024, 01:37:01 am
content: Hello,I have a Samsung NP270E5E-X02AU laptop. I'd like to unlock the advanced/hidden options in the bios. Is there a way to read/write to the bios chip so I can do this?The bios chip on the motherboard reads "winbond 25Q64CVSIG1328". I've tried using a CH341A programmer, however, have had no success. I've read on this thread (https://www.eevblog.com/forum/repair/ch341a-serial-memory-programmer-power-supply-fix/50/) that because it outputs 5V it's not compatible with my motherboards bios chip (supposedly runs on 3V), and that there are mods you can do to the CH341A to remedy this.I did one mod detailed by RaceJay on page 3 (reply #62), and it still did not work. I don't have the capacity to do more modding/soldering stuff.Is there a method to achieve what I want without having to do modding/soldering etc? If it requires purchasing another tool, I'd consider it, depending on the price.Thanks!

author: wraper
author_rank: Unknown
timestamp: February 12, 2024, 01:39:16 am
content: Without desoldering the chip it won't work.

author: Hentrox
author_rank: Newbie
timestamp: February 12, 2024, 01:52:18 am
content: The CH341A came with a lead/clip that clipped onto the bios chip. Why is desoldering necessary if devices with leads/clips exist?Edit: I assume you're talking about the bios chip when you reference the "chip"?

author: wraper
author_rank: Unknown
timestamp: February 12, 2024, 01:54:35 am
content: Because flash IC is connected to the circuit that will interfere with programming.

author: Hentrox
author_rank: Newbie
timestamp: February 12, 2024, 01:58:59 am
content: So, do only some laptops have "flash IC" that is "connected to the circuit board"?Because I used the CH341A with the lead/clip to flash a bios to a Acer laptop a while back.

author: amyk
author_rank: Super Contributor
timestamp: February 12, 2024, 02:43:01 am
content: Assuming the laptop itself is functional, boot to a suitable OS and read it from there. Writing is not without risk but doable.If the laptop is not functional, then you'll need a standalone programmer. I've seen chip-clips work well but it could be a matter of the voltage and being able to supply enough current that the IC works --- since it will try to power the rest of the laptop too.

author: wraper
author_rank: Unknown
timestamp: February 12, 2024, 02:45:22 am
content: Quote from: Hentrox on February 12, 2024, 01:58:59 amYou were lucky that particular circuit did not interfere too much, but overall it rarely works. Also there is a high risk of frying the motherboard.

author: Hentrox
author_rank: Newbie
timestamp: February 12, 2024, 09:48:13 am
content: SOLUTION FOUND - Pressing "CTRL + ALT + SHIFT + F4" while in BIOS unlocked advanced options.

author: Whales
author_rank: Super Contributor
timestamp: February 13, 2024, 03:06:49 am
content: My CH431A has a jumper for choosing between 5V and 3.3V. I successfully used it yesterday for reading & flashing a BIOS. The fiddly bit was the cheap clip (cleaning the clip and the chip seemed to help greatly).

author: wraper
author_rank: Unknown
timestamp: February 13, 2024, 03:31:06 am
content: Quote from: Whales on February 13, 2024, 03:06:49 amThat's about an issue in older CH341A. When selecting 3.3V, they still pushed 5V on data lines, mine was like that. Someone on this forum said that programmer he bought more recently no longer had this issue.

author: Whales
author_rank: Super Contributor
timestamp: February 13, 2024, 10:06:14 am
content: I just probed my CH341's pins with my multimeter and indeed yes it's sending 5V on some of themThat jumper is a lie, I'll get on fixing that.> Assuming the laptop itself is functional, boot to a suitable OS and read it from there. Writing is not without risk but doable.Not recommended. Flashrom doesn't support all "internal" programmers and even when it does it's common for certain regions to be blanked out ("security"). Using your own external chip programmer is much more reliable.> You were lucky that particular circuit did not interfere too much, but overall it rarely works. Also there is a high risk of frying the motherboard.I'd never survive desoldering and resoldering,one project I didrequired me to write to the chip dozens of times. The chip clip was perfect for that and caused me no dramas (even with its nasty 5V).On another more recent laptop I found that disconnecting the main battery made the reads and writes reliable. Prior to that I was getting a different image every time I tried to read (presumably due to something else trying to talk to the flash chip).

author: bioshackdaddy
author_rank: Newbie
timestamp: October 28, 2024, 08:25:27 am
content: People do it without desoldering them all the time, for instance coreboot, libreboot and probably 95% of people on youtube. yes it would probably be better to desolder them but I'm not comfortable to try that route yet. For 1 I dont have the proper equipment to do so.

author: coromonadalix
author_rank: Super Contributor
timestamp: October 28, 2024, 10:15:02 am
content: could be possible when or if you are able to put the system in continuous reset,the eeprom is energized but able to be reprogrammed, you put the programmer in parallel with say clips etc ..had no problems .. unless on other boards... there is only read, but write is hardware locked, wr pin grounded or put at vcc ?? ... remove the ic and flash it