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From: lowey@herald.usask.ca (Kevin Lowey)
Newsgroups: comp.lang.pascal
Subject: Re: arrays larger than 64k?
Message-ID: <1991Feb26.230955.29880@herald.usask.ca>
Date: 26 Feb 91 23:09:55 GMT
References: <26146@adm.brl.mil>
Organization: University of Saskatchewan
Lines: 31

From article <26146@adm.brl.mil>, by Mark@hamster.business.uwo.ca:
> I have a program that uses a large array.  I would like to have more than
> 64k available.  Is this possible?  About 128k would be nice.  I would even
> accept 64k if it did not decrease the memory for normal variables. I have
> tp6.0.

Turbo Pascal is limited in that it works in the real mode of Intel x86
processors.  It uses 64K segments, which means that no one data structure
can be larger than 64K.

Here is a trick that I use.  Remember that a two dimensional array is really
conceptually an "array of arrays".  Using this principle, I can have an array
of POINTERS.  Each pointer can point to a 64K array.  I can then access element
25,3 of this array with something like VARIABLE[23]^[3].

For example (from memory, so forgive minor mistakes):

  Program Test;

  TYPE
    largearray : array [1..60000] of byte;
    large_ptr : ^largearray;

  VAR
    The_Big_Array [array [1..20] of large_ptr;


Don't forget to use "New" to allocate the arrays pointed to by The_Big_Array,
and use "Dispose" when it is no longer necessary.

- Kevin Lowey