On Thu, 19 Feb 1998, Chris Torek wrote:

: I have no idea how this stuff is *implemented* in NetBSD, but
: there is a logical difference between:
: 
: 	there is memory from A to B and from C to D
: and:
: 	there is memory from A to D, but from B to C must
: 	not get used by the kernel

: The case of Sun-3 video RAM is much more arguable than that
: of SPARCs-with-boot-proms-reserving-space, though.  The video
: RAM *is* RAM, but is rather different from ordinary RAM

Same goes for Amiga "chip" RAM:  The native AmigaOS (and NetBSD, possibly up
to now but maybe changed since the last time I trowled through the md
sources back in 0.9) does make use of the (16-bit access) sound and video
RAM as actual system RAM.  But on systems such as an accelerated Amiga 2000
or 500, the chip RAM is unbearably slow for CPU execution, particularly if
you have a kernel sitting in that space.  Unfortunately, that RAM sits
between $00000000 and $00200000 (physical), but a MMU does wonders....

There is also the RAM space from $00C00000 to $00D00000 on some
(accelerated) A2000 and A500 systems that's almost as slow as the chipmem.
Amigaoids often call this space "slow fast."  Then there's "old fast
memory," from $00200000 to $00A00000, that can be 16 or 32 bit depending on
your CPU/accelerator board architecture.  Yuk.  :)

=====
===== Todd Vierling (Personal tv@pobox.com; Bus. todd_vierling@xn.xerox.com)
== "There's a myth that there is a scarcity of justice to go around, so
== that if we extend justice to 'those people,' it will somehow erode the
== quality of justice everyone else receives."  -- Maria Price