IreneR, I was mistaken about WinDWFlash accepting .exe firmwares, as it's limited to .cvt only. But if you use BQFlasher, it can accept either .cvt or .exe files.
I/O Magic and Hi-Val, for example, used to rebadge BenQ drives, thus, BenQ had "OEM" firmwares in the drives that were shipped to these OEM partners. The firmwares always started with the letter "G." However, features were disabled through these firmwares when using tools like QSuite or CD-DVD Speed. Thus, these Flasher tools were developed to allow OEM drives to accept Retail firmwares, ones that started with "B," this was considered as crossflashing. The last 1620 firmware is B7W9.