Is your feature request related to a problem? Please describe.
No.

Describe the solution you'd like
86box support AST Advantage! Adventure 4066d.

Additional context

Mainboard Info:
https://stason.org/TULARC/pc/motherboards/A/AST-RESEARCH-INC-486-ADVANTAGE-4000-SERIES-486-234.html

Mainboard bios download:
Advantage! Adventure 4066d BIOS 05560031.exe
http://www.sandyflat.net/digerati/ast486/drivers/d-bios/05560031.exe

05560031 -- Advantage Adventure 4066 bios unpacked

Mainboard Chipset Info:
SiS 85C471
https://archive.org/download/SiS-85C471-datasheet/SiS-85C471-datasheet_text.pdf

CL-GD542x datasheet:
https://wolumen53.com/pdf/CL-GD542x_CirrusLogic.pdf

CL-GD542X Technical Reference Manual Jan1994:
https://archive.org/download/bitsavers_cirrusLogichnicalReferenceManualJan1994_24841698/CL-GD542X_Technical_Reference_Manual_Jan1994.pdf

Computer Screenshot:

Screenshot of AST Advantage! Adventure 4066d running on 86box using [SiS 461] Acer v10 machine config:

86box CFG & NVR file:
86box cfg + nvr.zip

Youtube video:
AST ADVENTURE 4066d Cyrix 486 DX2 All-In-One Demo
https://www.youtube.com/watch?v=trFXOMVNtiA

Thank you.