I got an (almost) unmarked 486 board - only "P/N: 001-00486-018" and "MADE IN THAILAND" are printed on the board. Google did not help but a manual search through the pictures in TH99 database helped - it's Chicony CH-491E board. But the BIOS chip is missing and the BIOS file seems to be unavailable

Can anyone get this BIOS or at least a BIOS for anotherboard with UMC 491F chipset?
BTW.: It came with i486DX2/66 CPU and QDI QD6500A VLB IDE controller.