Related: How many hardware platforms are currently available with "pure" MBR support, that is, completely lacking in UEFI? My understanding is that all relatively recent systems have only UEFI and some have a hybrid mode through which they can recognize and load MBR.
I do not, but due to its size limit (64k IIRC), I doubt much could be added to it :)
>How many hardware platforms are currently available with "pure" MBR support
I have no idea, but on the 2 laptops I have, T420 and W541, MBR is supported. As far as I know, all x86 hardware should support MBR. Of course I do not run any version of Windows, so I can use MBR.
You are mixing up MBR (which is a disk partition schema) with the BIOS (old, pre UEFI) and CSM (literally UEFI Compatibility Support Module) boot processes.
Everything post 2012[0] is UEFI, most of time with CSM support but there are some machines without CSM at all.
You are really booting in UEFI and then it loads a CSM which proceeds with "legacy" boot mode.
T420 uses QM67 which is a second generation after Ibex Peak which was the first one to implement UEFI on Intel platform.
ie: https://pcsupport.lenovo.com/us/en/products/laptops-and-netb...
[0] Basically post Nehalem