Date: Thu, 11 Dec 1997 10:49:12 -0800 (PST) From: Tom <tom@sdf.com> To: Tom Bartol <bartol@salk.edu> Cc: hackers@freebsd.org Subject: Re: This IS relevant, you'll realize why later. Message-ID: <Pine.BSF.3.95q.971211104655.11383G-100000@misery.sdf.com> In-Reply-To: <Pine.BSF.3.96.971211093559.3358C-100000@dale.salk.edu>
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On Thu, 11 Dec 1997, Tom Bartol wrote: > On Thu, 11 Dec 1997, Jonathan Lemon wrote: > > > Hmm. One of my professors was claiming that with 128 bits, you would have > > an address space of 2^128, which would be large enough that you could do > > away with virtual memory altogether. > > > > Just give each piece of data it's own unique address, (ala Multics) and > > then never relocate it for the lifetime of the system. She pointed out > > that even the human genome database project is smaller than this. > > > > Somehow, I don't quite buy the argument. > > -- > > Jonathan > > > > I'd buy it for $5.00 -- > If the logic for each bit fit in a cube 0.14 picometer on a side you could > fit 2^128 bits in 1 cubic meter. Never mind that 0.14 picometer is > ~1/700th the diameter of a hydrogen atom and is only about 100 times > bigger than an atomic nucleus! So if we could fit the logic for one bit > in the space of a hydrogen atom, 2^128 bits would fill a cube ~700 meters > on a side! Or if one bit fit in a cube 0.25 microns on a side then 2^128 > bits would fill a cube ~1750 kilometers on a side (i.e. about 1/4th the > volume of the Moon)!!!! I think you are missing the point. The point is about address space, not physical RAM. The mapping of address space to physical RAM is flexible. Many current CPUs have a 4GB address space, but most systems have less than 4GB of RAM. Tom
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