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SubjectRe: using more than 2 GB as a ram disk
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"Albert D. Cahalan" <acahalan@cs.uml.edu> wrote:
> H. Peter Anvin writes:
....
> > Hardly "true flat-memory 64-bit"; it is a hacked 36-bit model where

> The Alpha only has about 43 address bits; is the Alpha not 64-bit?

That is with current chip implementation the address bus comes out
only as 43 bits, however internally it is fully 64-bit.

As a comparison from years back, processor called 68000 has 24 external
address pins, while it internally handles 32 address bits. Yet it can
handle only up to 16 megabytes of physical memory space.

With 43 address pins the directly addressable range is 2**11 times larger
than 4 GigaByte space of 32 address bits. (That is, 2048 times larger,
or 8192 GigaBytes -- a.k.a. 8 TeraBytes.)

/Matti Aarnio <matti.aarnio@sonera.fi>

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