To: atm{at}shore.net
From: mdholm{at}telerama.com
Reply-To: mdholm{at}telerama.com


> Wow - I haven't heard anyone even mention Forth in years.

Me either.  A long time ago I got a little interested in Forth.  I sent away for
a PDP-11 version of a simple Forth interpreter.  Only problem was I didn't
have a PDP-11 to run it on.  Well I knew enough about PDP-11 coding that I
thought I could translate it from PDP-11 assembly into assembly for the
HP-1000 that was about the only computer availabe to me at the time.  It
was a bit of a struggle,
because PDP-11's and HP-1000's had rather different architecture.  I got it
running though.  By the time I was finished with that, I was pretty worn
out with it and never did do much with the Forth.

Forth would have some advantages, it makes quite compact code, and for an
interpreted language, runs pretty fast.  It helps if you don't layer the
"words"
too thick.  If you keep pretty close to the native "words", Forth
doesn't have much overhead in getting down to the machine code.  As I
recall, there may be a mechanism for writing native code extensions in
Forth.  That would let you hand code anything that really needed to be
fast.

You do have to do more documentation work with Forth.  Especially, you have
to keep track of what is on those stacks!  I don't think anyone who has
done any work in Java can honestly say Forth is bad for readabilty, or
those regular expressions that Unix types love so much.

I think the Zilog Z80 derived microprocessors and the ones derived from the
Motorola 6800/6502 might be a bit more efficient with Forth than the 8080
derivatives.  (I think the 8080 family adressing modes are lousy!)  Back in
the early days of microcomputers, the Z80's got a bad shake because they
mostly had to run code written for the 8080.  The Z80 has more powerful
addressing modes that would streamline a lot of code, but even back then,
Intel was on top of the
compatibility heap.  The Motorola 68000 would be especially good, but that
may be more horsepower than you want for a drive controller.

Mark Holm
mdholm{at}telerama.com

--- BBBS/NT v4.01 Flag-4