On Feb 9, 11:32 pm, Tim Smith <reply_in_gr...@xxxxxxxxxxxxxxxx> wrote:
> In article <nG5kl.1850$v...@xxxxxxxxxxxxxxxxxxxxxx>,
> Chris Ahlstrom <ahlstr...@xxxxxxxxxxxxxxx> wrote:
>
> > After takin' a swig o' grog, Tim Smith belched out
> > this bit o' wisdom:
>
> > > In article <gmpoq0$ks...@xxxxxxxxxxxxxxxxx>,
> > > Sermo Malifer <sermomali...@xxxxxxxxxxx> wrote:
>
> > >> No it doesn't. Netbooks and the Kindle weren't limited by the GPL or
> > >> Linux, they were created because of them.
NetBooks were created in response to an initiative by Nicholas
Negroponte, who approached the Linux/OSS community with the idea of a
$100 laptop for kids in areas where traditional desktops and laptops
aren't practical because generators are often locally operated and are
turned off during various parts of the day or night.
The One Laptop Per Child project was more successful that people ever
imagined, lowering the costs of components and creating a machine that
could function with minimal memory and storage.
The result has been a computer that can be re-charged with solar
panels, small windmills, or even a kid peddling a stationary bicycle
hooked to a generator.
> > > The Kindle would almost certainly have been created even if they did not
> > > have Linux. *BSD would have worked fine for them. VxWorks would have
> > > been fine, too.
I remember the original VRTX. The VxWorks is much more *nix like.
Embedded Linux is also stripped down to be more "real-time" more like
VRTX.
Personally, my favorite "Real Time Environment" was FORTH. It's
almost a lost art because FORTH programmers are so rare - because it
takes very little time to go from concept to pilot to production with
few if any surprises. The only down-side is that FORTH doesn't scale
up well. It's create for a PDA, a Microwave oven, or even a remote
control for your television, but it isn't so great for use as a Web
Server or relational database.
Many of the concepts of FORTH live on in the Java JVM.
> > Wouldn't VxWorks have added a significant cost to the Kindle, though?
> Maybe. Maybe not. Linksys has switched some models of router from
> Linux to VxWorks, without raising cost, but they have usually at the
> same time dropped the amount of memory on those routers.
This is a good example of competition at it's best. VXWorks competes
with QNX as well as about 4 different flavors of embedded Linux, and
LYNX. They all have similar *nix like API sets, but they have kernels
specifically designed to support real-time and/or near real-time
interactions.
The fundamental difference between traditional Linux and Real-Time
Linux is that a "Nice -20" application (highest priority) always gets
executed immediatly after the interrupt indicates it's ready to run.
In traditional Linux or Unix, the priority is raised to make sure that
every process gets a chance to run proportionally to it's nice-ness.
This prevents "starvation" of lower priority processes by high
priority processes. Starvation would be a real problem in a
traditional server environment, but is often necessary if you have to
pecisely time engine ignition, guide a missle or predator flying at
300 mph or faster, at low altitude, or fire a machine gun or rapid
fire rockets.
> --Tim Smith
Tim, thanks for pointing out some of the other *nix like RTOS. It
does help to remember that Linux isn't the ONLY game in town other
than Microsoft.
Linux does tend to be better at keeping Microsoft OUT of the appliance
market.
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