Firmware for the Sony Vaio VPC-CW290X on Sony board MBX-226, with the HM55 chipset noted in the name. The ZIP is about 1 MB and likely holds a BIOS image for the SPI flash. MBX numbers are Sony's own mainboard designations for Vaio models. Technicians use such dumps to recover a board after failed updates or password and firmware corruption, writing the chip with an external programmer. Back up the original chip and ensure the image size matches the flash capacity.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @biosarchive. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.
Back up your own chip before writing any dump, and match the full board number and revision. Flashing guide →