Is your feature request related to a problem? Please describe.

I have found a site with the system and video ROM bios of Amstrad 5286. I'm not sure if the VGA BIOS is from a Cirrus Logic card, but the Amstrad 5000 series system disk contains an SCATEMM.SYS EMS driver, so I suspect it uses the SCAT 82c235 which is already emulated in 86box

Edit: : I was wrong, the VGA chipset seems to be C&T 452, not Cirrus Logic.

Here is the link:
https://banjosmods.wordpress.com/2021/03/18/amstrad-pc5286-bios-dump/

Here is the link with Amstrad DOS for 5000 series machines
https://banjosmods.wordpress.com/category/software/

As for the 5086, I'm not sure about the video chip, but uses the 82c100 chipset like the Victor V86 Laptop. So if some day the one of these machines is added will be useful for the other.

Here is the 5086 BIOS (But I suspect the VGA chip is not included)
pc5086.zip

Describe the solution you'd like
Consider if it is possible to add the emulation of the Amstrad 5286 machine to 86box.