Author: Christophe Theron
Date: 09:17:40 09/20/01
Go up one level in this thread
On September 20, 2001 at 11:28:52, Victor Zakharov wrote:
>
>Here is my opinion that worked with Forth-like systems for a few years. It was
>about ten years ago. so things can change thes days.
>
>>I think it is possible to find (or write) a C compiler for this Forth chip.
>>
>>A few years ago I have created for a commercial company a language which
>>resembles Basic. It was composed of a compiler, which produced P-Code, and an
>>interpreter, which executed the P-Code.
>
>Writing simple compiler for Forth is not a huge problem. But the problem is that
>Forth programming technology is based on implicit parameters passing through
>data stack. This way C programming technique will not be reflected to Forth in
>optimal way. I can say that simple compiler realization will be far apart from
>optimal. Writting compiler that produces optimal code is a large problem.
>
>BTW, writing programs on Forth is not much more complex than writing them on C.
>At least it is much easier than making this on x86 assembler. Language is easily
>extendable and this makes programming even pleasure (for simple tasks). But the
>problem is in the development and supporting tools. Modern compilers prevent
>huge number of bugs. Forth compiler didn't prevent something serious. I should
>say that there are much more posibilities in Forth to make a bug as compared
>with classic assembler due active using of data stack. Any small bug crushes the
>program in a moment. So debugging and making changes is the huge problem.
>
>>Looking at the specs of the Forth chip, I see other problems:
>>* 18 bits address bus => 256K words max address space (a little bit more than
>>512Kb).
>
>As for program code on Forth it is highly compact if native Forth is used. And
>it will not be so if compiler is used. I suspect that any PC program can be
>reduced 10x times if it is written of Forth by experienced Forth programmer.
>Numbers seem fantastic, but they are true.
>Surely data and hash tables can't be eliminated.
>
>>* the return stack is limited to 16 levels: you would probably have to bypass
>>this stack and create your own (or to add expensive logic around the existing
>>stack management) to avoid return stack overflows.
>
>This seems to be too high limitation. It is suppoded that nesting in Forth is
>higher than in usual programs.
>
>>> It can be implemented in as little as 2K (!). Thus, it
>>>has found a niche in embedded systems and prototypes. I believe they are aiming
>>>this chip at the embedded market (set-top web boxes). However, they have to
>>>develop all their own software for it.
>>>
>>>Chuck Moore, the inventor of Forth and these chips, is quite an iconoclast. He
>>>actually wrote his own PC Forth OS and Forth VLSI CAD system to design and
>>>simulate these chips. He can't understand why people buy big bloated operating
>>>systems instead of writing their own. :)
>>
>>He is a wise guy! :)
>
>I believe that Forth technology is excellent and it surpasses a lot of current
>technologies in a lot of things. But industry didn't accept it. So you should
>provide yourself with a lot of things to develop Forth programs. And I see no
>chance for Forth to survive in future. Too much money is already invested into
>other technologies.
>
>Victor
The very low power consumption and very high speed of the Forth chip is
something that should drive the attention of handheld makers. It seems that even
with a suboptimal compiler the performances are appealing.
But maybe there are other problems. For example I did not see any mention of an
interrupt handler on the X18 chip...
Christophe
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