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PDFORTH INFO [message #283067] Mon, 17 March 1986 19:31
Originally posted by: franco

Article-I.D.: iuvax.54600039
Posted: Mon Mar 17 19:31:00 1986
Date-Received: Wed, 19-Mar-86 05:17:06 EST
Lines: 61
Nf-ID: #N:iuvax:54600039:000:2916
Nf-From: iuvax!franco Mar 17 19:31:00 1986

I have recently been in touch with the author of the "PDFORTH" that I posted
to the net. I hope that at least most of you got that OK (I am frustrated
by the fact that so much of what gets sent on the net winds up as garbage
on the other end - at least I know the "PDFORTH" left here ok since I pulled
it off the net and got it to work). Anyway, I thought you might be interested
to know that what I sent out was a preliminary version of a FORTH that will
eventually be marketed by a (one-man?) operation called Bradley Forthware.
I have given the address below for anyone interested.

Also, I thought I would post part of our conversation which presents some of
Mr. Bradley's thoughts on his FORTH. Please note that I am posting the
information below only because some of you are porbably interested in the
info provided. I am in no way endorsing this product. For all I know the
info could be totally wrong. I have never met Mr. Bradley nor do I know
anything about him except that he claims to have authored the "PDFORTH"
(which, I suppose, should be relabeled BFORTH). Mr. Bradley does not know
that I am posting the text of part of our conversation. The sentences
preceeded by > are mine, the rest are his.

------------------------------------------------------------ -----------

The address is:

Bradley Forthware
295 Hans Ave.
Mountain View CA 94040

> By the way - it works with TOS in ROM (at least on my machine).

I got around to trying out the version you posted after I sent you the
message. I couldn't get it to work at all, but I found out enough to
figure out why it works with the ROMs. The version you have copies
itself to a fixed location in memory, which is about 0x50000 as I
recall. This works okay but it fragments memory and doesn't give
you the full benefit of the memory that is available.

(note: The above applies only to the version I posted)

> By the way, from some crude benchmarks I
> ran it seems that your FORTH is at least as fast as DRAGON FORTH.

My analysis shows that my Forth is faster than Dragon Forth without
the accelerators, and slower than Dragon Forth with the accelerators.
The difference is due to my use of direct threaded code versus the
the indirect threaded code used by Dragon Forth. Direct threaded code
eliminates a memory fetch from the NEXT routine, so that NEXT becomes
2 instructions assembled in-line -- specifically
MOVE.L (A5)+,A0
JMP (A0)

I believe that this is the best that can be done with the 68000, short
of compiling directly to machine code. On the 68000, Direct Threaded
Code is even faster then subroutine threaded code, which many people
erroneously believe is the fastest.

The Dragon Forth accelerators work by compiling sections of machine
code in-line, eliminating NEXT overhead entirely. I think that Dragon
Forth is a very good system. The multitasking especially is very
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