The Lenovo Thinkpad x61s is an excellent laptop. I have done several things to improve performance: reapplied thermal paste to the cooling fan, installed an SSD… It’s currently running Lubuntu 20.10 and working quite well.
While looking for information on the X61s I found out that the BIOS actually limits the speed of hard disks. There is also a limitation in BIOS on what kind of WiFi cards can be installed. I decided to update the BIOS, and after several attempts, here are the steps.
Tested on Thinkpad X61s.
- Format a USB stik to FAT32 (use Gparted)
- Use Unetbootin the USB stick bootable, with the FreeDOS distribution
- Create a directory called bios/ on the USB stick.
- Download the correct ISO image from ThinkWiki: Middleton’s BIOS
- Extract the contents of the .rar file
- There are 2 directories. I used the ISO in the directory called BIOS update/
- Extract the contents of the ISO file in BIOS update/
- Right click in File Manager and choose extract
- Copy the contents fro the extracted ISO file into the bios/ directory on the USB stick
- Restart the laptop and boot from the USB stick.
- Select the option:
FreeDOS Live CD with HIMEM + EMM386
- Enter the following commands at the prompt:
c:\
cd bios
flash2.exe \u
(use thedir
command to check the contents of the directory)
At this point I thought I was done, but I received the following error:Error 98: Not enough memory
The following steps resolve the issue: - Restart the laptop, enter the BIOS and disable the setting for memory protection:
Security -> Memory Protection -> Execution Prevention: Disabled
- Save settings, restart and boot from the USB stick.
- Repeat steps 8-10.
- The process takes a couple of minutes and then the system gives a ‘beep’.
- After the beep, there is an error message over the entire screen
Invalid opcode
At this point I thought that everything was lost. However: - Restart the laptop, boot from the hard disk, and everything is working fine!
The results are excellent!
- SSD read rate before BIOS update: 142 MB/s
- SSD read rate after BIOS update: 277 MB/s
Here are screenshots from gnome-disks, comparing the results before and after update.


Useful links:
Hey hello, i am getting error “Error code = 98” on my x61 and Ex. Prevention are disabled in bios. What should I do?
Just selected FreeDos Safe Mode and its worked!
I’m glad that it worked! Hope you laptop runs smooth and fast 👍