UEFI - Enable Legacy Mode
Legacy Mode is an option that basically enables computers to install and run operating systems that do not provide UEFI support. This is the case for Windows 7 and earlier, as well as many smaller Linux distributions. This is because the UEFI will be disabled, resulting in the computer running straight from the BIOS, as was the case prior to the release of Windows 8.
Although Manjaro does indeed provide support for UEFI, unless Legacy Mode has been enabled, the user-friendly graphical bootup screen seen in the installation guides will not be shown. Instead, a somewhat plain-looking menu will be shown in its place. This is the menu for the UEFI.
Step 1: Access The BIOS Settings
The UEFI system sits on top of your computer BIOS. As such, it is necessary to go into the BIOS settings in order to enable the Legacy Support option in turn. This is achieved by tapping the appropriate Function (F) key - usually <F10> - immediately after turning on or rebooting your system. The <F9> key will usually access the UEFI system itself.
If you accidentally end up in the UEFI menu, then you may see a screen that looks like this.
As illustrated however, it should still be possible to access the BIOS settings from here, on this occasion by pressing the <F10> key.
Upon entering your BIOS settings, then you may see a screen that looks like this.
Step 2: Access The Boot Settings
Once in the BIOS settings, you should be able to use the <left> and <right> arrow keys to navigate the top menu tabs (usually Main, Security, System Configuration and Exit). You can then use the <up> or <down> arrow keys to highlight and select the options provided in these tabs.
1. Navigate using the <left> / <right> arrow keys to the System Configuration tab.
2. The Boot Options section should be now visible. Highlight this by using the <up> / <down> arrow keys.
3. Once highlighted, press <enter> to access it.
Step 3: Enable Legacy Mode
Once in the Boot Options, the Legacy Support / Mode option should be visible.
1. Highlight the Legacy Support / Mode option by using the <up> / <down> arrow keys.
2. Once highlighted, press <enter> to access it.
3. As illustrated, a new menu will pop up, where 'Disabled' or 'Enabled' may be selected. Highlight Enabled by using the <up> / <down> arrow keys, and then press <enter> to confirm.
As illustrated, a warning message will appear, stating that enabling legacy mode 'may make the system unable to boot the OS'. Highlight Yes by using the <left> / <right> arrow keys, and then press <enter> to confirm.
Legacy Mode has now been enabled. Now press the appropriate Function key to Save and Exit. In this instance, the <F10> key must be pressed to do so.
A confirmation message should appear asking if you want to Exit Saving Changes. Highlight Yes by using the <left> / <right> arrow keys, and then press <enter> to confirm.
Your computer will now begin to boot, and you will now be able to install any operating system that does not support UEFI (including Windows 7).