OK, I had a look.
Strictly speaking this does not state a flash-based storage, rather "A block-erasable, write-once, multiple-read memory device, the memory device having one or more blocks". This has several effects:
- it would cover much more than just flash-based devices
- it avoids issues relating to load levelling etc.
Also, strictly speaking, a flash-based system would work without wear-levelling, it would not just work that well or for very long. Independent claims are drafted with the fewest features possible that enables the invention to work, even though it might not be optimal.
Features that make the invention work better or well are typically found in dependent claims. You see a little about this in claim 10:
10. The method of claim 8 wherein each block has an erase count that indicates the number of times the block has been erased and wherein the step of selecting a block in the memory further comprises the step of selecting the block in the memory based on the erase count.
Most patent offices have requirements to unity, that the claims should be directed to a single invention. Supposedly this is to make the claims easy to read, in reality I suspect it is to earn more fees. This means that claims directed to wear levelling would be in a different application and claims relating to write amplifications would be in yet another application.
> However, should you create a real flash storage - you're likely to infringe this patent.
Considering priority according to parallel EP0557736 is 29.01.1992 the patent will have lapsed most places. The US has however different rules though that also have changed over time.
A quick review showed no third party observations, oppositions or re-examinations. It would appear that at the time competitors did not consider the patent a problem.
If instead you can find something fresher you could try a third party observation. In a few cases there are no fees and you do not require a professional representative.
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