I have this question because I tried to crossflash my DH-20A4H to 20A1H just for testing but I reflashed back to CK's patched firmware (QP5A) and then to QP5B from LiteOn site. My drive came originally with QP5A firmware, this firmware was "A" or "S" version? Actually the drive has "S" firmware. I wanted to try one of CK's patched firmwares and I read this:
*DUAL: These firmware flashers have two firmwares installed and will automatically detect you firmware type (A/S) and flash the required patched firmware. These packed files are much larger because RAR solid will not work on files larger than 4MB
And also this:
* It is understood that two different Laser Diodes exist in the A4 models. Please make sure you backup your original firmware using the Flash Utility, before flashing to this firmware, so it can be restored if your drive's LD does not match the type set in the current patched firmware.
I didn't backup my original firmware.
This firmware detected that I have the "S" version but I don't know if it's OK since I crossflashed from a 20A1H firmware (that does not have "A" or "S") back to 20A4H firmware. Is there a way to know? thanks.