Subject:
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Re: where leJOS firmware ?
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Newsgroups:
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lugnet.robotics.rcx.java
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Date:
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Thu, 12 Feb 2004 12:50:54 GMT
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Viewed:
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5276 times
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In lugnet.robotics.rcx.java, Sole Msitu wrote:
> Hi everybody.
>
> I'm trying to guess where exactly the leJOS firmware is stored. All domcuments
> i've read say that it's in the 32K RAM. But i ask my self why they say RAM; if
> you turn off the RCX neither the firmware or the user programms doesn't
> disappear.
The 32K RAM in the RCX is powered by the batteries even when the RCX is turned
off. This is why the firmware (leJOS or otherwise) does not get erased when you
turn the unit off. But if you remove the batteries for a few minutes, it does
get erased. This is also why the standard LEGO firmware is capable of retaining
user programs and the contents of the data log.
In fact, the RCX never really turns off; it goes into sleep mode. The H8
processor is still turned on, but simply halted from executing instructions.
When you press the power button, it generates an interrupt that wakes the
processor back up again.
It's a little bit counter-intuitive, but this is how many devices with "soft"
power switches work. The power switch doesn't have an "on" and "off" position,
allowing the unit to turn itself off after a period of inactivity and save its
batteries when a child (or adult) forgets to do so.
Hope this helps!
- Chris.
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Message is in Reply To:
 | | where leJOS firmware ?
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| Hi everybody. I'm trying to guess where exactly the leJOS firmware is stored. All domcuments i've read say that it's in the 32K RAM. But i ask my self why they say RAM; if you turn off the RCX neither the firmware or the user programms doesn't (...) (21 years ago, 12-Feb-04, to lugnet.robotics.rcx.java)
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