Subject:
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Re: mindstorms NXT and memory
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Newsgroups:
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lugnet.robotics
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Date:
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Mon, 9 Jan 2006 13:19:21 GMT
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Viewed:
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8951 times
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In lugnet.robotics, steve <sjbaker1@airmail.net> wrote:
> pisymbol wrote:
>
> > The ARM architecture has been around for years and has been a very effective
> > RISC based embeddded CPU core. That Wiki article does a good job explaining the
> > history and the various implementations of the ARM core (ARM7 is the NXT but I
> > have no idea which version of ARM7 it is, I can guess from the specs but it
> > would be nice to know the EXACT chip).
>
> I would be inclined to guess that the ARM is just the CPU core
> implemented in the same chip as all the other stuff the NXT uses.
Right but that's not what I'm really asking! :-)! I'm sure its a variation of an ARM7 chip which will implement the standard ARM ISA. However, with any ARM7 implementation it can be catered to a specific applications. From the ARM website:
"The ARMv7 architecture defines three distinct processor profiles: the A profile
for sophisticated, virtual memory-based OS and user applications; the R profile
for real-time systems; and the M profile optimized for microcontroller and
low-cost applications.
All ARMv7 architecture profiles implement ® technology which is built on the
foundation of the ARM industry-leading Thumb code compression technology, while
retaining complete code compatibility with existing ARM solutions. The ARMv7
architecture also includes the ™ technology extensions to increase DSP and media
processing throughput by up to 400 percent, and offers improved floating point
support to address the needs of next generation 3D graphics and games physics,
as well as traditional embedded control applications."
Source: http://www.arm.com/products/CPUs/architecture.html
So for example, is the NXT chip capable of SIMD? I suspect it is since the NXT FAQ talks about playing music. What about Jazelle? I know someone asked about using Java with the NXT (a nice idea from the programmers standpoint). I know the J2ME KVM can be as small as 128K.
> One of the huge reasons for picking the ARM is that it's very well
> suited to being integrated into the same chip as a bunch of other
> stuff.
>
> > I haven't compiled anything for ARM in quite sometime (as many of stated, you
> > can probably develop a cross environment to natively build ARM7 code).
>
> That much is very easy. The GNU C and C++ compilers have back-ends for
> the ARM and there are LOTS of people doing all sorts of things on ARM
> devices so there is plenty of expertise out there.
>
> For example, there are people porting Linux onto the GameBoy Advance
> and the Nintendo DS...so you just KNOW there is a ton of freebie stuff
> out there for this CPU.
Oh no doubt Steve. In fact, someone stated that historically ARM was "hard" to
program for and I have to disagree. One of the advantages of ARM is its
simplistic ISA. Since its RISC (in the classical sense), its ISA is already
straightforward to use, i.e. there aren't half a dozen instructions that can
yield the same result like x86 and each instruction has the same basic format.
Moreover, since these are embedded chips, their execution units are very simple.
I think the ARM7 has a simple classic 3-stage pipeline (Fetch, Decode, Execute).
This makes it easier on the compiler guys to generate streamlined assembly
unlike Intel which at this point has made assembly look like Java byte code!
The first order of business for the NXT is to have some kind of sane cross or
toolchain environment that people could download and use.
-aps
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Message has 1 Reply:
 | | Re: mindstorms NXT and memory
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| (...) > NXT FAQ talks about playing music. You can play music quite easily without SIMD. (...) > NXT (a nice idea from the programmers standpoint). I know the J2ME KVM > can be as small as 128K. Well, you can run Java on an RCX... (URL) you (...) (18 years ago, 9-Jan-06, to lugnet.robotics)
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Message is in Reply To:
| | Re: mindstorms NXT and memory
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| (...) I would be inclined to guess that the ARM is just the CPU core implemented in the same chip as all the other stuff the NXT uses. One of the huge reasons for picking the ARM is that it's very well suited to being integrated into the same chip (...) (18 years ago, 9-Jan-06, to lugnet.robotics)
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