RAM means Random Access Media/Memory. Compare to serial/linear access, as with tapes. Nothing says you have to read a large ammount of linear data once you get there. Because a hard-drive can seek to any given spot without having to pass the heads through all locations in between, it is random access. Ditto with CD and DVD media. And Memory is vauge, but I haven’t seen anything which suggests that only dynamic ram, or other volatile storage media applies.
Also, a weird paging scheme has nothing to do with RAM. A page just means that there is a page counter and an offset counter. Both need to be changed to point to all addresses. Neither is limited to being incremented or decremented; you can directly store any desired value. Thus even with a weird paging system, it’s still RAM.
There is a middle-ground. Imagine a series of 1K (2^10) punched cards, each with 1KB of data on it. If these cards have to be shuffled through in order, to find the correct card, but by knowing the address of the data on the card, the read/write head can position directly to the byte desired, is this random or linear access?
I ask this because everything is a variation on this. In disks, the head has to be moved, and if it goes from track 1 to track 15, it crosses 2, 3, 4, …, and 14 before getting there. And if it’s looking for sector 12, and the head gets to the track on sector 3, the device waits for the right sector to rotate around. There’s obviously a linear component to this, but it lets you skip fairly quickly to the desire element.
RAM can even have some linear elements to it, usually because of optimization. Often a read request for one byte results in between four and sixteen bytes being read, then the correct byte being pulled out and used. The requested address is random, but often sequantial reads are faster, because the memory can be told to fetch the next set of bytes rather than given a whole new address to read from.
So, if you nitpick enough, nothing is truly random access unless the heads teleport to the proper place, and all data is arranged so that individual bits can be read just as quickly from any area of the device as any other. Or, you can say that anything which doesn’t make you wait while it rewinds through 1500m of tape is random.
I tend to support the latter view.
Then, onto the issues of speed/size.
Yes, the RIAA is trying to block writable DVDs, because they allow copying movies. They make it seem like only movie pirates require this kind of storage, but then you see the many legitimate uses of VCRs and writable tapes… And this is worse, because VCR tapes were primarily video only, a writable DVD will be useful for much more than just copying movies. I have 4-5 gigabytes of old .zip files, work I’ve done for various clients, which I’d love to archive onto one DVD instead of many CDs; I’m sure many people have legitimate uses for large removable media.
The capacity will get higher. Currently I believe one layer on one side is writable, the pre-written DVDs can have two layers on each side. When writable DVDs become more common the manufacturers will have incentive to produce the higher capacity writable disks.
And, as more people buy the disks, production will increase and the economies of scale the computer industry is used to will kick in, making the disks eventually about the price of CD blanks now.
Either that, or another technology will overtake DVDs before they really take off…
btw, RAM doesn’t necessarily mean rewritable. A WORM disk can be RAM, in that you can read and write in any fashion, but of course, can only write to each area once.