What is the Firmware??
Some questions (And some answers too)....

This time, The focus is on the firmware "Version". I had worked on various drives to get the exact answer. The issue is, What's the "exact" difference between various firmware versions for a same family. Let's say, what's the the difference two Victors having QPR100-05 & QPR100-07? And at what aspect they are "inter-compatible"?

Now, let's get the real concern behind this quest. Most of the times, when it's hard to get the exact f/w version of a PCB or modules/ROM, how far can we go to make the drive compatible with the version we have in hand? Let's say, if we have any module currupted for the above Victor QP07 and we have no such exact drive's module, will the QP05 work? If not, what things we will have to make it compatible? Let's start-

Now here is what I have found in my research and experience:-

There are four things which work in conjuction as per the f/w version-
1.Disk
2. Heads
3. ROM
4. Modules

These are the things, which keep pace with each other. Now, here comes the family pecularities. It varies on vendor to vendor, family to family and model to model that what should be what in according to f/w version to run the drive. In some drives, they are totally compatible within the family, in some -the model is must. In some, some modifications is required in the ROM while in some, it has to be done with modules. Here are the details on the drives I have experienced and researched with:
(Please note -When writing f/w of different drive, it's you, who has to deal with the defect lists and adaptives parameters settings. Otherwise you may screw the whole drive, leaving it totally unrecoverable)

Seagates
Medalist: ROM and Modules should be of same version. Thus, it's necessary to write (or swap) the ROM accordingly.
All U Series (except U6 and UXX): Same as Medalist
U Series 6: The ROM should match with the drive's f/w version accordingly. The version "3.39" and "3.99" ROM's are interchangable with each other while rest of the versions are interchangable with each other. And, it is must to have the Main Overlay (OCCT) Module is of the same version as ROM. So, when writing ROM- it is necessary to write this module too.
Barracuda: Everything should be of same firmware version.

Samsungs
Spinpoint: In spinpoints, the model is not a critical requirement. Though peoples gets confused about it easily, because different models has different ROM f/w Version according to the drive capacity. But, it is the same ROM, which gets changed itself, when it reads the capacity (Heads) information from M/C. Thus, the second character of the Version is purely neglectable.
As I mentioned the Disk/Heads/Modules/ROM theory above, it comes in role in samsungs. As, Samsungs has different comibantion of Disk and Heads, it is must to much certain things. For Voyagers (V11P), Victors and Victor plus, To matching the heads type is necessary as per the original ROM version. Wheather it is the "SAE" head, The "Read Rite" head or the "ALPS" head -we will have to match it accordingly.
In Puma, To matching the heads, as well as disk type is necessary. Either the Disk is "Trace" or "MCC", it should be matched with the new ROM version type.
In Rest of the spinpoints, Heads and Disk type can be ignored. We only will have to concentrate on matching the versions first letter to work with ROM.

I will try to post on more vendors, as I will keep discovering about them.
Your comments are welcome...

Gurus...please give some more information and ideas about this you have..

regards
harddiskbug@yahoo.com

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To be continued on Msn online. Btw... Something wonderful is coming...

In U6 3.99 and 3.39 are not compatible even by the ROM code and the CPU on thier PCB is also different .

Yes rameez, they are compatible. Even the CPU doesn't make any difference. If not on thousands, then atleast on some hundred drives I have experienced about interchanging 3.39 with 3.99. But as I told, the OCCT module must be equalant with the ROM version. It means, when uploading the ROM 3.99 to 3.39, you will need to write the OCCT module of 3.99 too (and vice verca).
Once again, CPU does NOT make any difference. Though, they look different. (Here I would like to mention that the drives with matarial completely hold around the CPU are more reliable rather then the straight-square shape CPU's -This is the ONLY difference )

BTW, do you have any fight with Yahoo's management? I had thought, you lost in the hard disk jungle and was about to contact Yahoo's CEO about the matter....

Hoping to get in touch with you again soon. Have to discuss something with ya.. (you can mail me your shedule to be online on yahoo..I also will try to be only that time...)

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P.S.
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Many things are not exact in the Samsung section !

Yes ur write we have to upload the OCCT module that is the only difference , but it does not match directly i mean to say .

I dont use yahoo much but will see u sooner .

I have the same firmware on some families still not good enough (think alpine aplus). In fact, each drive may have SA start in different spot, even with same firmware. Actually, I have 3.xx that works in an 8.01 drive. I deduced that only reason they are compatible, is that they have same heads, smooth, and offset of SA. Yet, some with same FW do not work.
This family very unique in that regard.

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In Alpine series compatibility of pcb depends upon the APP code .

Yes, the offset of SA seems to be saved in APP zone in flash. So, you can have different FW and still compatible with same offset.

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question.. barracuda as noted is same version.. but it's only same version if it's the same model..from what i observed on the stickers.. so does that mean I don't have any chance of swapping PCB's from other models? cos i'm thinking of swapping pcb from a lower harddisk size model..