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 05:59:16 GMT
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Original-From:
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steve <sjbaker1@airmail.!AntiSpam!net>
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Viewed:
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9329 times
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Brian Davis wrote:
> In lugnet.robotics, steve <sjbaker1@airmail.net> wrote:
> > The point is that having such an incredibly small amount of memory
> > (by modern standards) forces you into ugly compromise solutions from
> > your shiney new system from day #1.
>
>
> I'm curious - I'm a physicist, not by any means a hardware type. What *is* a
> standard amount of on-board FLASH for a embedded system?
It depends on the application obviously...but thinking of consumer
devices that cost around the same ballpark as the NXT and which are
likely to be sold in similar quantities, we have PDA's, handheld games,
MP3 players and digital cameras.
* PDA's generally have somewhere in the tens to hundreds of Megabytes
of flash and maybe a few megs of RAM.
* The Nintendo DS hand-held game system has 4Mbytes RAM and it's
teeny-tiny game cartridges have hundreds of Megabytes of ROM memory.
* A typical digital camera has a few megabytes of RAM and hundreds of
megabytes of flash.
* A solid-state MP3 player would be likely to have hundreds of Megabytes
of flash and very little RAM.
> The NXT uses some sort
> of ARM processor (what the heck does that stand for anyway?)
ARM == Acorn RISC Machine
RISC == Reduced Instruction Set Computer
Acorn == A British company that designed and manufactured the ARM until
one of the big companies took them over.
RISC computers are generally quite hard to program at the machine code
level, but easier and more efficient for automated program compilers.
The ARM has been around in different incarnations for maybe 15 to 20
years. The ARM7 used in the NXT is a couple of generations behind the
cutting edge (eg the Nintendo DS uses an ARM9 as it's main CPU). The
big thing that makes the ARM popular for embedded systems like this one
is that the ARM circuitry is fairly compact (because it's a RISC
machine and therefore runs very SIMPLE instructions very fast). This
allows system developers such as LEGO to put lots of other circuitry
onto the same chip and thereby save a ton of money. Given the small
amount of RAM, it's likely that the RAM is on the same chip as the
ARM. It's even possible that the 8 bit microprocessor is also on
that same chip.
> - how FLASH-rish do
> these come? And how hard is it to mate such a CPU chip with another chip or two
> of FLASH?
Expanding the amount of memory (presuming you were prepared to do some
surgery to the circuit board) might be very easy - or it might be
impossible. It depends greatly on whether the main CPU chip has enough
address pins to access more memory.
> > If this system is going to be around for the same amount of time as
> > the RCX (what? nearly 10 years now?) - it ought not to look antiquated
> > from the very beginning.
>
> Well, to be fair, the same could safely be said of the RCX. It had less RAM
> ten years ago than my Apple ][ did more than 20 years ago!
Yes - but that would be to compare a desktop system with an embedded
computer.
Memory capacities double about every one to two years - so you'd
expect maybe between 5 and 10 doublings in capacity between the RCX and
the NXT if they were following industry trends.
So 32Kb for the RCX would become between 1 Mbyte and 32 Mbytes for the
NXT.
If you think that's agressive, look at the Nintendo Advance (64Kb,
released in early 2001) which has grown to the Nintendo DS (4Mb, late
2005) which is six doublings in four years!
> > You can buy Flash memory USB 'thumb drives' for $8.50 in quantity
> > with anywhere from 128Mbytes upwards.
>
> How hard is it to interface a thumb drive with a device like the ARM?
It would be pretty tough.
> From other discussion here the difference between slave and master USB devices seems
> to be important.
Yes. It's crucial.
In effect, the USB port on the NXT is only useful for talking to a PC
(or perhaps a PDA if it had a USB host port).
> How much extra hardware or software do you need to make
> something like the NXT a USB master device, so it could handle things like a
> thumb drive?
It's more major surgery - but it's hard to say how hard it would be at
this early stage. It's certainly going to be a lot more than cutting a
couple of tracks and soldering in a couple more wires.
From a software perspective, there are plenty of OpenSourced drivers
for USB flash devices that could probably be adapted to make this work,
I doubt that would be a problem.
> > I'm so horrified about this that I'm half convinced that this must
> > be a mis-print and that the NXT *surely* has 128Mb and not 128Kb.
>
> With Bluetooth at least we'll have access to potentially a whole computer's
> worth of memory (at a slower rate? I really need to learn about Bluetooth).
Yes - that's an interesting direction.
I'm also pretty un-knowledgeable about Bluetooth. I don't think there
are Bluetooth flash memory drives or anything though. A quick search of
Bluetooth devices suggests that just about the only things people are
using this interface for is cellphone hands-free operation and wireless
audio headsets.
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Message has 5 Replies:
 | | Re: mindstorms NXT and memory
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| (...) Just FYI, I programmed an ARM chip over 10 years ago (so it must have been a less powerful one than this). The assembly code was surprisingly clean, simple, and powerful. ARM is a great architecture. Something like BrickOS with a GNU C (...) (19 years ago, 9-Jan-06, to lugnet.robotics)
| | | Re: mindstorms NXT and memory
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| (...) Well, there's a significant cost above and beyond the electronics here. The NXT *might* be comparable to a PDA, but tossing in 500+ precision-molded little plastic parts probably drives the cost up considerably (heck, just from buying sets I (...) (19 years ago, 9-Jan-06, to lugnet.robotics)
| | | Re: mindstorms NXT and memory
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| (...) Well, *any* machine is harder to program at machine code level. If you mean assembly, I diagree. I spent the first 18 years of my career on IBM mainframes, and the last 5 on SPARC machines. They each have their advantages and disadvantage from (...) (19 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'm curious - I'm a physicist, not by any means a hardware type. What *is* a standard amount of on-board FLASH for a embedded system? The NXT uses some sort of ARM processor (what the heck does that stand for anyway?) - how FLASH-rish do these (...) (19 years ago, 9-Jan-06, to lugnet.robotics)
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