You were absolutely right. It was not easy to get stable readings with the CH341a. On my first attempts, I got different results on each reading. Today I succeeded a little better and managed 4 readings with the same CRC value. ((Just to be safe, I checked the files with "certutil -hashfile biosRead.bin md5" and all the files had the same MD5 hash).
Do you have the opportunity to look at the attached file if everything is ok?