My MSI Wind U100 has finally arrived (a few days after Christmas when I was expecting it, but still in 2008 luckily) and it has been exhibiting several strange Windows crashes. Since the U100 version I ordered comes with a "bonus" 1024M of RAM, which (by my understanding) are not installed by the OEM, but by the online store that sells the netbook, I naturally suspected memory problems and reached for Memtest86+.

Unfortunately Memtest86+ does not run from Windows or Linux as "normal" software does, because it needs to replace whatever OS exists and trash the memory as part of its job. For most folks the easiest way to run Memtest86+ is to burn the distributed ISO image and boot from the CD (or boot it off a floppy for the few that still have such a peripheral). But netbooks don't have CD/DVD drives. The only workable option then is to run Memtest86 from a bootable USB disk.

There are many tutorials on how to create bootable USB disks using things like syslinux, isolinux, makebootfat, but most of these are boring to even skim, let alone put in practice. After looking around for a while I found a simpler solution:

• Download unetbootin
• Run it and install a FreeDos image on the USB stick (unetbootin has a specific menu option for this — it will download the FreeDos setup files for you automatically)
• Download Memtest86+ — use the "Pre-Compiled EXE file for USB Key (Pure DOS)" version
• Unpack the zip file (it should contain a single executable) to the root directory of your USB disk.
• Ensure legacy USB support is enabled in BIOS
• Boot off the USB stick and choose one of the LiveCD options (not "Install"!)
• At the DOS prompt, change drives by typing "c:" (this will take you to the USB disk) and run the Memtest86+ executable (e.g. mt211.exe).

Memtest86+ will then run on your system for an hour or so (hopefully telling you nothing is wrong). At the end, you will need to reboot the computer, because (as mentioned above) Memtest86 completely replaces any running OS. But you weren't likely to stick around in FreeDOS any longer anyway.

This still takes several steps, but it's light, non-error-prone GUI work and doesn't require handling a lot of disparate components like other methods. You can use this method for running other DOS-only executables (e.g. legacy software or BIOS flashing programs.)