On 2014-07-19 6:08 PM, Enrico Lazzerini wrote: I have done this before manually, I did not use the position 47 but rather altered one of the existing table entries, but that should not make any difference as long as the parameters in the table are correct. Did you check the output from this BIOSUTIL to make sure that the table entry looks correct? Other than that the only other important thing is to make sure the checksum is correct, I seem to recall that the algorithm used to checksum the ROM expects the last byte (word?) to roll the sum over to 0, but it is a long time since I did this and I may not be remembering this correctly, nor do I remember if the AT does the sum in bytes or words. What happens when you try to boot the new ROM? Do you get any response from it? If you get nothing two things come to mind, the BIOS image you downloaded is no good or you interchanged the high and low byte ROMs. If the checksum is wrong it will post an error message, if it seems to do its memory check ok but won't boot off the disk that might suggest that you are not pointing at the correct drive table entry or some parameter in the table is not correct. If it was me I would not be downloading a ROM image off the web I would just dump my existing BIOS and make whatever changes where necessary to it. Paul.