I am talking about SGI workstations, indeed the 1995 ones didn't support (without modification) 48bit, instead it was "only" 12bit per channel, 3 channels, thus 36bit.

Here is a photo of John Carmack using such workstation: https://external-preview.redd.it/EnhEls7GJgm9UxR8FE9Dc3FfH4X...

In 1997 then they launched the "Octane" Workstation line, that could output 4 channels of 12bit, thus reaching 48bit.

https://hardware.majix.org/computers/sgi.octane/

One of the purposes of these machines, was make HDR images (among other things).

Sadly for THAT, I don't have time to track sources now, I am busy with something else.

As for a monitor that could support this stuff, one is SONY GDM90W11 that could do 1900x1200