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From: bright@Data-IO.COM (Walter Bright)
Newsgroups: comp.os.msdos.programmer
Subject: Re: Virtual Memory for the Heap
Message-ID: <2616@dataio.Data-IO.COM>
Date: 6 Aug 90 18:41:14 GMT
References: <2698@mindlink.UUCP>
Organization: Data I/O Corporation; Redmond, WA
Lines: 16

In article <2698@mindlink.UUCP> a35@mindlink.UUCP (Bruce Atherton) writes:
>6600m00n@ucsbuxa.ucsb.edu (Rob Blair) writes:
<< The main problem with swapping data is that
<< it is accessed 'asyncronously'. i.e.  You never know when you will need
<< to be in, since pointers can point anywhere.  Code is always accesed
<< with calls, and can be routed through a overlay maneger.
<As long as a function was called every time a pointer was dereferenced,
<the time that the data was accessed wouldn't be a problem.  Of course,
<that function would somehow have to be able to tell what page the
<pointer belonged to, and swap it in if necessary.
<Second, you could use the Zortech method of assuming that pointers will
<never want to point into the BIOS.  This strikes me as dangerous, since I can
<think of reasons why I might want a pointer to point there.

You *can* have pointers pointing into the BIOS. They just cannot be _handle
pointers, they must be regular far pointers.