Flashing VBIOS of 8800m GTX - wrong filesize

Hi!
I have a problem with flashing a new vbios to my Clevo nVidia GeForce 8800m GTX or rather the bios chip.
I have desoldered the 1 Mbit (128 kByte) BIOS chip (MX25L1005MC) and now I´m trying to flash it with my raspberry pi 3, spi, flashrom setup.

The problem I´ve got is the following.
The readout flash file from the chip seems to be damaged. It has a lot of empty (0x00) ranges, and cleaned by those empty ranges, I get a file with about 30 kByte size.
Or is the bios splitted somehow?

For this video card, I can only find bios files with about 60 kByte (f.e. the vbios version 62.92.23.00.14 with 60.5 kByte).

My question is now, how is this smaller bios file arranged in the bigger bios chip?
I guess, it is put at the beginning of the memory and the rest of the memory is filled with 0x00 or 0xFF?

Needs the end of the smaller bios file anyhow edited before flashing?
The end of the smaller bios file looks like (look at the last byte):


Does anybody know, what the meaning of the last byte is? Is it sort of a checksum?