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Re: Relocatable Blocks

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Hans Bezemer <the.beez.speaks@gmail.com> writes:
>Albert van der Horst wrote:
>
>> In article <CE4017C0.3A79%igvb@btopenworld.com>,
>> This all seems pretty useless without words to
>> address into the blocks that are allocated.
>True. Having made a simple VM block system myself, the problem is not to
>generate or load handles, but making memory access fairly transparent -
>especially when it crosses block borders - in which case you have to
>transparently load more than one block, unless you take other precautions.

Either you have misunderstood what Ian van Breda proposes or I have.
My understanding is that he proposes a MacOS style (pre MacOS X)
handle system for explicit main (RAM) memory management (i.e., an
alternative to ALLOCATE FREE RESIZE), no disk/flash blocks involved.

The difference from ALLOCATE FREE RESIZE is that the memory block
returned by NEW-HANDLE can be moved around by the memory management
library.  This was useful in old MacOS, which did not have virtual
memory at first.  In other OSs like non-ancient versions of Unix
virtual memory is used in various ways that mostly eliminate the needs
that led to handles in MacOS.

One problem with handles is that addresses into the block referenced
by the handle are very short-lived, so you have to start addressing
from the handle for pretty much every access.

- anton
-- 
M. Anton Ertl  http://www.complang.tuwien.ac.at/anton/home.html
comp.lang.forth FAQs: http://www.complang.tuwien.ac.at/forth/faq/toc.html
     New standard: http://www.forth200x.org/forth200x.html
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Relocatable Blocks Ian van Breda <igvb@btopenworld.com> - 2013-08-25 20:21 +0100
  Re: Relocatable Blocks Paul Rubin <no.email@nospam.invalid> - 2013-08-25 14:04 -0700
    Re: Relocatable Blocks Ian van Breda <igvb@btopenworld.com> - 2013-08-29 19:55 +0100
  Re: Relocatable Blocks albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-08-26 11:34 +0000
    Re: Relocatable Blocks Hans Bezemer <the.beez.speaks@gmail.com> - 2013-08-26 14:58 +0200
      Re: Relocatable Blocks Hans Bezemer <the.beez.speaks@gmail.com> - 2013-08-26 15:30 +0200
      Re: Relocatable Blocks anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-08-26 14:33 +0000
        Re: Relocatable Blocks Ian van Breda <igvb@btopenworld.com> - 2013-08-29 20:22 +0100
  Re: Relocatable Blocks Mark Wills <markrobertwills@yahoo.co.uk> - 2013-08-26 07:08 -0700

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