Path: utzoo!attcan!uunet!salt.acc.com!ucsd!sdcc6!ir230
From: ir230@sdcc6.ucsd.edu (john wavrik)
Newsgroups: comp.lang.forth
Subject: Re: Essence of Forth
Message-ID: <7694@sdcc6.ucsd.edu>
Date: 22 Feb 90 17:20:08 GMT
References: <9002210135.AA20505@jade.berkeley.edu>
Organization: University of California, San Diego
Lines: 43



Mitch Bradley writes:

# When running under an operating system, the underpinnings of both memory
# allocation and file access is a call to the operating system, which is
# not standard Forth.  The irreducible requirement is some set of words to
# get at those system functions.  Direct system calls cannot be standard,
# because then they would depend on the particular OS.  The next obvious
# solution is to construct a wordset that can be efficiently implemented
# on top of most operating systems, yet provide a portable interface.
# 
# That is exactly what the file and memory allocation wordsets in BASIS do.

Gee, I'm sorry -- I thought you were talking about dynamic memory 
allocation schemes. It is true that many operating systems do not, 
for obvious reasons, attach to a Forth system all the memory in its 
address space. Users do, indeed, need to be able to increase the 
dictionary area on such machines. (I'm not sure that I see why this
needs to be done by a Standard wordset -- but if you want to specify 
it, what harm could it do.) 

I was thrown off, I guess, by your discussion of "inconsistent" 
handling of strings by the Forth system itself -- and your mention
of the need for a dynamic memory allocation system to make a string
package useful. I just assumed that you were pushing for the 
incorporation of a particular dynamic memory allocation system and
a "consistent" string package to be built in to Forth.

As long as we're just talking about a word to specify the static memory 
requirements of Forth, perhaps running with other tasks, everything is 
fine. The rudimentary heap management built in to operating systems for 
allocating memory for tasks is really not a suitable basis for the kind 
of dynamic memory scheme needed by some Forth applications. 


                                              --John

                                                  John J Wavrik 
             jjwavrik@ucsd.edu                    Dept of Math  C-012 
                                                  Univ of Calif - San Diego 
                                                  La Jolla, CA  92093