My point is that nothing happens between system clock pulses. The state of a computer remains unchanged. With fast and cheap NV memory, you could build a PC that could literally suspend its state between processor pulses and instantly restore the PC to the state before suspension.
Many believe that the memristor could provide such an operation. BIOS, OS, video, processor cache, all memories would be NV and totally freezable such that no bootstrapping would ever occur (except with MicroSoft products which would have to be restarted after the blue screen of death) :-) Terry On Wed, Dec 31, 2008 at 11:27 AM, Jed Rothwell <[email protected]> wrote: > I wrote: > > ". . . whether the RAM saves its content or not, during startup it is > entirely rewritten anyway. In fact, this is exactly what happens during > recovery from sleep or hibernation: the RAM contents are loaded from the > disk. This takes practically no time." > > It is the same process as a virtual memory overlay, which computers have > been doing since the 1950s. RAM contents are swapped in and out to disk with > no checking or program setup. This works fine . . . except when it doesn't. > > I do not know how much the overlay technique is used nowadays in Windows. > Back when computers had 64 kB of RAM the contents was constantly being > written out to disk and then read back in somewhat less often. (That is, it > was written out into never-never-land and lost forever). Even when it worked > right it caused "thrashing." > > One of the first IBM commercial computers from the 1950s had no RAM. All > data was stored on a rotating cylinder, the grand-daddy hard disk. It was > all virtual, you might say. > > - Jed > >
