Path: utzoo!attcan!uunet!willett!ForthNet
From: ForthNet@willett.UUCP (ForthNet articles from GEnie)
Newsgroups: comp.lang.forth
Subject: Experimental Ideas
Message-ID: <1381.UUL1.3#5129@willett.UUCP>
Date: 24 Jul 90 01:38:09 GMT
Organization: String, Scotch tape, and Paperclips.  (in Pgh, PA)
Lines: 42

Category 3,  Topic 5
Message 33        Mon Jul 23, 1990
D.RUFFER [Dennis]            at 01:29 EDT
 
Re: F.SERGEANT [Frank]

What's so "pure" about polyFORTH?

Indirect threading.  Parameter fields contain definition tokens which point to
code field addresses which point to code.  Certainly not the most efficient,
but the most universal technique across various hardware platforms.

Block files.  Our linear block arrangement is portable across all our
platforms (with or without OS support) and our Least Recently Used buffer
manager makes for very efficient use of the disk I/O path.

Line editor.  Our line editor follows the pattern desribed in Starting Forth
and is used identically on all platforms.  When we are able to add scroll
locking and function key support, it is easier to use and more efficient than
any other method.

Threaded vocabularies.  Traditionally using 8 threads, each of the 8
vocabularies are linked in a unique sequence.  The vocabulary search order is
implicitly defined by name making the locating of words highly deterministic.

Round-robin multi-tasker.  A very simple method of task support which requires
minimal task switch overhead.  By using a self modifying approach, a sleeping
task can be passed over with a simple jump.

That is all I can think of right off hand.  Over the years, all Forth
programmers have "improved" on these techniques with varying degrees of
success.  I think every Forth has roots in these techniques, and many have
developed more efficient approaches.  Some systems have found better ways of
doing various parts, but polyFORTH is the only one I know of that contains all
of these techniques in their pure form.  We have also experimented with
various alternatives, but we seem to always come back to the simplicity of
these methods.

Maybe there is a reason.   DaR
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