Copy C:\Grub4dos\grub.exe to the root of your boot drive/device. Boot from the device and wait for the DOS prompt, then type grub.exe [ENTER] to load grub4dos. If using Windows 9x, press the [F8] key to enter the safe mode boot menu and choose option Command prompt only or Safe mode command prompt only, then type grub.exe [ENTER].
Copy C:\Grub4dos\grub.exe to the root of your boot drive/device. Add an entry to config.sys - to add an option to a Windows 98 (SE) boot disk menu, edit config.sys (in a text editor such as notepad) and add the following entries (for changes to original config.sys see here - changes are in red text) -
The legacy of the Atheros AR5BBU12 driver is a cautionary tale. It highlights the "driver gap" where hardware outlives its software support. When Windows 10 adopted the Universal Bluetooth Driver model, many AR5BBU12 modules were left to function only in basic mode, losing features like EDR or hands-free profile stability. Today, any machine still using this chip is likely running Linux, where the open-source btusb kernel module natively supports the CSR chip without issue. In the Linux world, the driver is a permanent, maintained fixture. In Windows, it is an orphan.
Because Qualcomm acquired Atheros, the hunt for the correct driver became a digital scavenger hunt. The "story" of this driver is one of compatibility: Bluetooth Module Atheros Ar5bbu12 Driver
Officially, Atheros (acquired by Qualcomm in 2011) provided drivers for Windows 7 and 8. However, Windows 10 and 11 lack native, stable inbox drivers for this module. Users often resort to manually installing legacy drivers from OEMs (e.g., Acer’s 2013 driver package) or using modified INF files. Common issues include the “Code 10” error (device cannot start), Bluetooth audio stuttering, and failure to resume from sleep. The absence of Windows Hardware Quality Labs (WHQL) certification for newer OS versions means the driver operates in an unsupported, often unstable state. The legacy of the Atheros AR5BBU12 driver is
Several desktop and ThinkPad models use compatible Atheros drivers. You can search by serial number on the Lenovo Support portal to find the specific package for your machine. Microsoft Update Catalog: Today, any machine still using this chip is
The Atheros Ar5bbu12 driver is software that enables the operating system to communicate with the Bluetooth module. The driver acts as a bridge between the operating system and the hardware, allowing users to configure and use the Bluetooth module. The driver provides several functions, including:
To ensure that your Bluetooth module functions optimally, it's essential to keep the driver up-to-date. Here are the steps to update the Atheros Ar5bbu12 driver:
A sample config.sys is included in the Grub4dos download, this can be used to replace config.sys on your boot device - if using the sample file you will be prompted to press the [space] bar to start Grub4dos.
Autoexec.bat can also be used to launch Grub4dos - simply edit the file and add entry grub.exe.
To install grub4dos code to a hard disks MBR via DOS, copy C:\Grub4dos\BOOTLACE.COM to the root of a DOS bootable drive/disk. Now reboot your PC and boot into DOS. If using Windows 9x BOOTLACE.COM can be executed from a dos box (start > run > type command [enter]).
To install Grub4dos code to the MBR of the first hard disk (usually the first hard disk set to boot within the BIOS settings) use command -
To install Grub4dos code to the MBR of the second hard disk use command -
To avoid installing Grub4dos to the wrong disk use a third party tool such as MBRWizD.exe (available here) to check the disk order. Copy MBRWizD.exe to the root of the DOS bootable device and type MBRWizD.exe /List - you should be able to identify the correct disk from the attributes outputted by the command (to install to disk 0 - use command BOOTLACE.COM 0x80; to install to disk 1 - use command BOOTLACE.COM 0x81; etc.). You will also need to copy grldr and menu.lst to the root of a (supported) local drive/disk.
Using the Grubinst package, it is possible to install Grub4dos code to the partition boot sector. Although this feature is documented in bootlace.com, attempting to install to the bootsector (using the command bootlace.com --install-partition=0 0x80) results in the following -
Use instead the DOS version of grubinst tool - at the time of writing this guide the most recent version available is version is grubinst-1.1-bin-dos-2008-01-01 (file name grbins16.exe). Use command syntax grbins16.exe -p=n [device] or grbins16.exe --install-partition=n [device] (where n = partition number, starting from 0 for first partition. e.g. grbins16.exe -p=0 (hd0). If using Windows 9x, run grbins16.exe from a dos box (start > run > type command [enter]).
grldr must be copied to the partition on which the bootsector was installed, and the partition must be active. See here for Grubinst download.