Newsgroups: comp.robotics
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From: nagle@netcom.com (John Nagle)
Subject: Re: Forth's reputation
Message-ID: <nagleD42tCK.7vp@netcom.com>
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Date: Thu, 16 Feb 1995 04:48:20 GMT
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jfox@netcom.com (Jeff Fox) writes:
>This chip is a Forth engine in that the instruction set is basically
>Forth, but the stacks are very tiny, so it is a really minimalistic
>Forth chip.  For more information send me email or check out
>http://www.dnai.com/~jfox

     Forth chips have an amusing history.  The first one by Moore
had an error in the multiply unit (the product always came out even)
and he couldn't afford to have a new rev made.  The literature thus
pointed out that, after all, most multiplies have at least one even
operand.  (No, I'm not making this up.)

     He also offered a development system that used a 3-button keyboard
as input.  That's all you had; three buttons on which you could do
chords.  It was actually possible, although painful, to program with this.

     Harris eventually took over the product and made one that worked
right, selling it into the embedded systems market.  It may still be sold.
But it was never a big seller.

     Forth is a nice language for embedded programs that are close to
the hardware.  I've used the New Micros Forth for the 68HC11, which is
OK, although on the slow side, for a mobile robot with a steerable
sonar.  But maintaining large Forth programs written by others is 
considered very painful.  Despite that, sizable applications (including
Swivel-3D for the Macintosh) have been written in Forth.

					John Nagle
