Keeping links relies on the unreliable notion that the desired information will remain static. Sadly, as with the SD specifications, that's not the case. Spec's are reduced in size and usefulness as the subject component ages. I've seen components that once occupied entire chapters of data books reduced to a couple of pages over the years. If I need detailed information about how a particular component did its job, a couple of pages that simply tell me that the part once existed won't help. Had I discarded my old data books when the new ones arrived, I'd be in real trouble now. If I want to see how Western Digital thought one should implement a floppy disk interface, the old, circa 1978 data book will tell me. The 1990 version won't.

That applies not only to links that rely on manufacturers to keep data available, but also on the relative permanence of the content. Neither is guaranteed if one doesn't keep the information oneself.

I still rely on the printed specification for the HD44780 LCD interface when I want to be sure I "have it right." Sooner or later, what's available on the www won't be as complete. All one needs to consider is the various discussions about the venerable i8255. It's not widely available any longer, but there are still a few manufacturers that produce/sell it. If one wants to replace one, where should he get it? Will that one work as a replacement for the old one? What about attempting to replace its role in a new circuit? How does it work? Why doesn't it work? All these questions rely on spec's ... spec's often no longer available, hence requiring guesswork if the original spec isn't on hand.

That's what I had in mind.

Yes, it requires a bit of judgment deciding what to archive and what not. Just my experience with the Maxim/Dallas DS894x0's is a good illustration. The earliest data sheets had specifications for parallel programming. The current ones don't. Now, those old spec's may not apply to new silicon, but they allow one to ask rational questions.

RE