some first impressions

Walter Bender walter.bender at gmail.com
Sat Aug 11 15:23:39 EDT 2007


On 8/11/07, Guylhem Aznar <olpc at guylhem.net> wrote:
> On 8/11/07, Jameson Chema Quinn <jquinn at cs.oberlin.edu> wrote:
> > I've archived this discussion on robotics/LED output, with some points of my
> > own, on the wiki at
> > http://wiki.laptop.org/go/Electrical_output.
>
> Thanks a lot for the summary on the wiki.
>
> A quick suggestion : if there is a serial port in the XO (according to
> the boot message, there is one) maybe it could also be used.
> rx/tx/gnd/vcc already allow a lot of fun stuff and experimentation.

There is one, but it is not brought out from the
motherboard--something we have argued about quite a bit internally.

>
> By the way, if there are other beginners out there, who are a bit lost
> in the wiki, http://wiki.laptop.org/go/Getting_started_programming is
> a great page to get started.
>
> There is too much information to read everything in one day, but so
> far I have found the following documents very interesting: (I'm new to
> python, but I know a little javascript)
>
> http://wiki.laptop.org/go/Understanding_sugar_code
> http://www.pygtk.org/dist/pygtk2-tut.pdf
> http://www.ibm.com/developerworks/linux/library/l-sugar-olpc/index.html
> http://downloads.egenix.com/python/LSM2005-Developing-Unicode-aware-applications-in-Python.pdf
> http://wiki.laptop.org/go/DCON
>
> This page however looks incomplete : turning the backlight back is
> impossible with the current instructions:
> -bash-3.2# cat /sys/class/backlight/dcon-bl/power
> 0
> -bash-3.2# echo 1> /sys/class/backlight/dcon-bl/power
> -bash-3.2# cat /sys/class/backlight/dcon-bl/power
> 0
>
> I guess I will have to look for more information since the sugar gui
> does it just fine.
>
> Regarding the underlying gnu/linux system, to explore how it all works
> together, my preferred method actually is ssh and console mode.
>
> To do that, type alt+m to get a terminal, then passwd root and passwd
> olpc to setup passwords for remote access.  This also let you use the
> console on ctrl-alt-F1 (magnifier) or with chvt 1
>
> Currently I am exploring a little more the fedora distribution, the
> hardware support, and I am doing some benchmarking, especially for
> power management stuff.
>
> Last night I found that closing the screen turns off networking, while
> keeping the mesh network (as specified), but does that until the
> battery is fully depleted. Wow.
>
> I wonder if a graceful suspend when there is say only 50% of battery
> power left wouldn't be nicer to the users. Else, kids who come to the
> same conclusion may prefer to fully turn off the laptop to have some
> power left to read books/play games/whatever in the bus after school
> etc. There should be a good equilibrium between the user own interest
> (having some power left) and the community interest (keeping the mesh
> network up)
>
> Also I noticed SHM support has been compiled in, but /dev/shm in not
> used. Is it by design? I couldn't find references on the wiki.
>
> /var /tmp and similar files could certainly live there to save some
> nand write cycles. Did that on the zaurus : you simply keep a tarball
> of a clean /var in / (say /.var.tar) which you untar as soon as the
> shm has been mounted. Before the shm is mounted, you keep a skeleton
> /dev/shm/var so that  /var symlink is not broken and application which
> may depend on the existance of the directories won't be confused.
>
> Guylhem
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>


-- 
Walter Bender
One Laptop per Child
http://laptop.org


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