Hello everyone! Guys I want to try AHCI 2.00h. My DeviceID 3A 22. Who knows how to fix the checksum, that would be "00".

Yes, please, anyone!! ^^^ If anyone can tell me which byte is the checksum byte to fix, I can correct checksum for him, but I'm just not sure which byte it is anymore since it's been so long since I edited Intel AHCI roms.

plutomaniac @Sylar76 @MiesMosel @dsanke @chinobino @davidm71 @ket @SoniX @ex58 @hancor

He said Fernando told him it's byte 0x4h, but comparing several different versions of 1.20E, some have same value at 0x4h and all are zero checksum8, so 0x4h can't be the checksum byte I think and maybe Fernando was not 100% sure?

@Lost_N_BIOS

The easiest way if the location of the checksum byte is unknown.
The last byte in the file is changed, as for example in the OROM SATF Marvell.

I do not think that the byte at offset 0x04 is corrective.

There is another suggestion.
To the original files add a block of 512 bytes as 0x00.
Correct the new file size at offset 0x03.
construct the checksum in the last byte at the end of the file.

Edit:

Sorry!
Filesize offset 0x02
Dec / 512 = Dec -> Hex (1 byte)

Thanks @Fernando and @SoniX - I considered testing last byte change, but I was not sure if that would be OK either, at least we know in this situation any bad edit will not = brick, only failed load of AHCI module and BIOS can be reflashed.
I used to know the byte, back in the 1.20E editing days, but I can't remember it now and even looking at several different versions of 1.20E I can't tell.

SoniX - I already know how to correct file size bytes, so that would not be an issue, but thanks. I know how to add 512 byte chunk, but am not exactly sure what you meant to add if not 200h (200h / 512Bytes, or add 512h)?
Is this correct now, using 200h added of 00 + 3A 22 DevID + checksum & File Size fixed - https://ufile.io/rgktjnfp
How does this work OK, if BIOS routine checks the usual/proper checksum byte for it's stored value, or that doesn't matter since we correct overall?

@Lost_N_BIOS
I checked AHCI 2.00h.
On GA-EP45-DS3P AHCI 2.00h works and loads. AHCI 2.00h sees my SSD but the bios itself does not see SSD, sadness.

@SoniX - Above method works then, thanks!

@Dagal - sounds like this AHCI Module is not compatible with the BIOS then, since AHCI is loading and showing SSD I don't think the mod to it is causing any issue or it wouldn't load itself.

* Edit - after more testing, checksum correction at byte 0x07h without padding adjustment also works!! But either way, SSD/HDD is not visible to BIOS, to be selected as a boot device, so not compatible with this particular BIOS

@Fernando Orom VROC/ RSTe 6.3 sSATA (attached OROM SATA and sSATA, source)

@Fernando There is version 7.0.0.2008 for "OROM Intel VROC for SATA", no ?

@tistou77 Where did you find the Oroms?

@lfb6 In SoniX's archive

@Fernando
Yes I have 7.5 version for "EFI RaidDriver"

I do not use any RST / RSTe driver (NVMe only) and the Windows 10 native driver for the DVD ROM
I don't know if it's really useful for me to monitor these EFI / OROM