Head Adaptives ROM Question

[ddrecovery]

In the newer version of PC3K, when importing Seagate Head Adaptives I receive a message asking which ROM block to use 1 or 2? I have not seen this before?

[fzabkar]

I have analysed several Seagate ROMs in previous threads. It appears that current ROMs have two halves, with the contents essentially replicated in each half. On at least one occasion I noticed that one half was altered after a firmware update while the other half remained unchanged. IIRC, the adaptive sections were identical, in which case your question would be moot.

If you can upload your ROM, I can show you what to look for.

[ddrecovery]

I have analysed several Seagate ROMs in previous threads. It appears that current ROMs have two halves, with the contents essentially replicated in each half. On at least one occasion I noticed that one half was altered after a firmware update while the other half remained unchanged. IIRC, the adaptive sections were identical, in which case your question would be moot.

If you can upload your ROM, I can show you what to look for.

Do you know which half of the ROM the drive actually uses by default? Presumably one is a backup? If you upload head adaptives from a donor drive into one of these ROM blocks (you can only upload one at a time) how do we know the new head adaptives are actually being used by the drive? We could upload into both I guess as we always keep a copy of the original ROM, but seems a little labor intensive.

[fzabkar]

I suspect that there is flag in each header which identifies the active half.

[fzabkar]

See https://forum.hddguru.com/viewtopic.php ... 9&start=40

[Dima_RnD]

In the newer version of PC3K, when importing Seagate Head Adaptives I receive a message asking which ROM block to use 1 or 2? I have not seen this before?

There are two copies of ROM and it's not matter what copy do you select.

[ddrecovery]

In the newer version of PC3K, when importing Seagate Head Adaptives I receive a message asking which ROM block to use 1 or 2? I have not seen this before?

There are two copies of ROM and it's not matter what copy do you select.

Could you explain how that works if only one copy has the new head adaptives?

[fzabkar]

Why is it so difficult to patch the adaptives into both halves of the ROM? Am I missing something?

[ddrecovery]

Why is it so difficult to patch the adaptives into both halves of the ROM? Am I missing something?

Its not difficult. I just want to understand the workings of the two halves of the ROM. However it is time consuming if you are accessing the ROM via boot code which after a head swap most of the time you are, and especially if you have to short the board to get access. Just curious as to why uploading head adaptives to either half of the ROM (if I read the post correctly) works. Just seems weird.

[fzabkar]

Here is an example of the changes written to the ROM by an official Seagate firmware update:

https://forum.hddguru.com/viewtopic.php ... 2&start=40

The updated code was written to the second half of the ROM. The RAP, CAP, and SAP adaptives were identical in both halves.

[ddrecovery]

Here is an example of the changes written to the ROM by an official Seagate firmware update:

https://forum.hddguru.com/viewtopic.php ... 2&start=40

The updated code was written to the second half of the ROM. The RAP, CAP, and SAP adaptives were identical in both halves.

I can understand that, you wouldn't want to change head adaptives with a firmware update. But we are talking about just changing one side of the ROM. Maybe I'm thinking too much about this and should just accept it.... Or perhaps the RAP is changed on both halves of the ROM and other changes only affect one half. I'll do some experimenting and let you know.

[fzabkar]

If I were approaching this problem, I would start with a ROM where the two halves were essentially identical. Then I would apply a firmware update.

Before the update, one half would be active and the other half inactive. If the update goes to the second half of the ROM, then it stands to reason that it would become active while the first half would become inactive. I would then compare the changes in the non-updated half of the ROM. I would expect to see differences in the active/inactive flag and in the checksum. ICBW but at least it's a plan.