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.

1. Format a USB stik to FAT32 (use Gparted)
2. Use Unetbootin the USB stick bootable, with the FreeDOS distribution
3. Create a directory called bios/ on the USB stick.
4. Download the correct ISO image from ThinkWiki: Middleton’s BIOS
5. Extract the contents of the .rar file
   1. There are 2 directories. I used the ISO in the directory called BIOS update/
6. Extract the contents of the ISO file in BIOS update/
   1. Right click in File Manager and choose extract
7. Copy the contents fro the extracted ISO file into the bios/ directory on the USB stick
8. Restart the laptop and boot from the USB stick.
9. Select the option: FreeDOS Live CD with HIMEM + EMM386
10. Enter the following commands at the prompt:
    c:\
cd bios
flash2.exe \u
    (use the dir 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:
11. Restart the laptop, enter the BIOS and disable the setting for memory protection:
    Security -> Memory Protection -> Execution Prevention: Disabled
12. Save settings, restart and boot from the USB stick.
13. Repeat steps 8-10.
14. The process takes a couple of minutes and then the system gives a ‘beep’.
15. After the beep, there is an error message over the entire screen
    Invalid opcode
    At this point I thought that everything was lost. However:
16. 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:

• Middleton’s BIOS
• T61 Middleton BIOS how to USB stick upgrade
• https://forum.thinkpads.com/viewtopic.php?t=117042