The History behind the BAM

[Macaroni]

Can anyone point me in the direction of how Commodore developed the concept of the BAM, or if that isn't possible, maybe a clue where the Commodore BAM came from? Of course, this kind of a feature existed with the 1541 disk drive (for the Commodore 64), and also somewhat earlier for the 1540 disk drive (for the Vic-20). And I will guess it also existed a few years earlier with the drives associated with the PET.

I know that the 1571 used to let you write on both sides of a 5.25 inch diskette. And especially for the sake of software compatibility, an extra BAM was created for that very purpose.

So, at this point, I am curious where it came from. Thank goodness I am somewhat familiar with the United States Patent and Trademark Office. And I thank my lucky stars, it even has a website at http://www.uspto.gov but what piques my curiosity is how patents work in the United Kingdom. Didn't Commodore start in Canada? Is there a master registry in the UK for patents? What website has a search engine for scoping out patents in the UK? If you want to scope out patents that might be vaguely related to the Commodore BAM, go to the aforementioned website and scope out things like Track, Sector, Block, and Disk. That sort of thing. Pay attention to the patents filed in the 1970s - they are relevant to the world Commodore found itself in. I wouldn't at all be surprised Commodore Business Machines chose to treat it as a poorly kept secret - that is, a trade secret, in a manner of speaking -and so declined to treat it as anything patentable; after all, they were the sole source of the computers that used their kind of "DOS," so why patent a thing like a BAM? Now, for what it's worth, it was many, many years ago - way back in 1985 or 1986 - that I'd gone with my Mom & Dad to the Sage/Stride convention in Sparks, Nevada, and there was a symposium there that discussed how to put a patent on your work instead of a copyright, and what kind of relief you can get from breach of patent rights, as opposed to breach of copyright. It only goes to show you, a lot of people were dissatisfied with copyrights, and were looking into the matter of patents for securing their creative works.

Finally, my next question is this: in the United States, is the concept of a BAM protected by a particular patent number? Or is it merely a matter of copyright, and that's it?

Any help would be appreciated.

[Macaroni]

To refresh people's memories, the BAM is a combination of a series of ranges, where each range represents block usage for the track in question, and to be a little more precise, each range consists of a bitmap (probably 3 or 4 bytes long, maybe 4 or 5 bytes long - somebody ought to correct me here), and the addition of a 1 byte counter. That 1 byte counter represents total blocks free (for that particular track).

If you want to know how many blocks are free on the disk, you can add up all those 1 byte counters to get a total. Although tracks in the days of the Commodore 64 were never more than 40 sectors long (though I can think of exceptions), there is the matter of adding your tracks together, you are likely to get a subtotal somewhere along the line, somewhat greater than 8 bits, you will need at least two bytes to store your grand total.

At this point, if I have misstated the facts, somebody correct me.