Subject:
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Re: Something else is needed, I think...
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Newsgroups:
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lugnet.robotics
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Date:
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Mon, 3 May 1999 23:26:48 GMT
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Original-From:
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John A. Tamplin <jat@liveonthenet.comSAYNOTOSPAM>
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Viewed:
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1492 times
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On Mon, 3 May 1999, Kekoa Proudfoot wrote:
> Maybe the JVM is, in spirit, close to what we want; but can you honestly
> say that porting the JVM to the RCX will be easier than writing something
> from scratch, perhaps using some of the better features of the JVM as
> inspiration? I personally think I have a very good idea of what it will
> take to write new firmware from scratch. It isn't that much work in my
> opinion, especially considering all the work it took getting to the point
> where writing replacement firmware is even possible.
I guess it depends on what you want in your firmware. I have been
working on my own object-oriented kernel, and I have written an
object-oriented kernel for an embedded I/O controller before, and it is a
big job. That is just the OS, not counting a language interpreter.
Perhaps if your goals are less ambitious the OS is less of a project.
If you are considering only the JVM, the only tricky part in the port of
the interpreter is the lack of 64-bit integers and memory constraints.
The real problem is the interaction with the OS (for threading specifically)
and the fact that I don't think there is an OS currently available which
supports the threading facility JVM needs, which means writing an OS.
> Right now, in my opinion, the features are the key part to get out in the
> open at this time. If there are specific features of the JVM you really
> like (and I presume there are many), I would like to hear about them. But
> if all you have to say is, (paraphrasing) "the JVM rocks!", you should know
> better than that, those sorts of statements are not very useful to anybody.
The things I like about using JVM (in no particular order):
===========================================================
1) huge variety of development tools and expertise on many platforms
2) compact bytecode
3) full-featured support for objects, threading and exceptions
4) compiler and interpreter do strict static error checking, interpreter
does strict dynamic error checking
5) JVM is all the interface required to the OS (ie, in C you have libraries
to do threading, you can have direct access to the hardware, etc)
6) portability (specifically it would be easy to write RCX emulation classes
and run that on any JVM). If it is designed right, the same user code
should run on any future upgrade of the RCX.
Things I dislike
================
1) relying on garbage collection on a memory-constrained device
2) licensing issues requiring that it implement the full JVM spec
John A. Tamplin Traveller Information Services
jat@LiveOnTheNet.COM 2104 West Ferry Way
256/705-7007 - FAX 256/705-7100 Huntsville, AL 35801
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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Message has 1 Reply:
 | | Re: Something else is needed, I think...
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| (...) So this is a nice start at least. Regarding things you like, I'm going to ignore 1) and 6) because they are not features of byte code, they are features of Java; you either use the JVM and you get them, or you do not use the JVM and you do not (...) (26 years ago, 3-May-99, to lugnet.robotics)
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Message is in Reply To:
| | Re: Something else is needed, I think...
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| (...) Maybe the JVM is, in spirit, close to what we want; but can you honestly say that porting the JVM to the RCX will be easier than writing something from scratch, perhaps using some of the better features of the JVM as inspiration? I personally (...) (26 years ago, 3-May-99, to lugnet.robotics)
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