I have a ROM dump file that have the first 256 bytes (0x00 to 0xFF locations) full of zeros (00h).

It is valid to have such values at the beginning of the ROM?

The drive is a Pre-ROYL (Caviar WD400BB) but for every ROM I have seen the first byte is already fullfilled with the 0x5A value indicating the PMCBlock #0, and their corresponding 32-byte data entries for every subsequent PMCBlock #nn (at least, according to earlier NazYura workings and researching).

After ROM address 100h, the ROM data entries appear ok, showing PMCBlocks 08h, 09h, and 0Ah. After that, the ROM contents appear ok to the end of the ROM (128K).

Since the ROM dump was made with an universal programmer, I suspect that the operator made a mistake -either at reading the chip, or writing the file- masking the first page of the EEPROM (first 256 bytes) with a default value of all zeroes.

Additional notes not regarding hard drive matters: masking the EEPROM chips contents through page-organization is possible and it is common practice with Flash and Serial EEPROMS. It is a common inherent property of the chip organization itself and has nothing to do with the purposes of hard drive matters. Every manufacturer implements it own organization for Paged operations (write, erase, or erase-before-write, protect, etc.) For example, Atmel AT25F1024A chips are organizated with 256-byte Page Mode, but ST M25P10 chip have 128-byte Page Mode.

So, it is valid to have such zero values at the beginning of the ROM?

Thank you in advance.

PD. Is there a repository or some other web site that still contain the useful researchings of NazYura? I had only found broken or dead links.

In replying to myself, I strongly believe the answer is a NO. To me, it is not logical and valid to have such first 256 bytes filled with zeros (00h), since that ROM space is where PCMBlocks #00 to #07 are assigned. I believe that it is a file corrupted by the operator, either at reading the chip or writing the Hex file (using an universal chip programmer).

But I am in no way an expert. Just a beginner trying to learn, so I greatly appreciate your opinions for this issue.

Thank you in advance.