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DPRG: software donation

Subject: DPRG: software donation
From: R. Steven Rainwater srainwater at ncc.com
Date: Mon Jun 16 10:27:05 CDT 1997

On Mon, 16 Jun 1997 09:14:10 -0500 you wrote:

>Here's some of the issues we've discussed:

I might as well throw in my two cents...

>1.  Price:
>	Windoze95: *$54,  Linux: $20.00(CD-Rom), WindozeNT: $???

You can install Linux for free via Internet. (might take a while over
a modem connection, though)

>2.  Users having it installed on their desktop PC:
>	Windoze95: nearly everone
>	Linux: just a few

This is probably the best point in favour of Win95 over linux. For every
one person that has Linux you'll find 10 that have Win95...


>3.  Compatibility:

How about:
	Source to kernel and device drivers available?
        Win95: No,    Linux: Yes

>	16 Serial ports:  Windoze95: Yes, Linux Yes
>	Languages (C, Tcl/Tk, Java, etc): Win95:  Yes, Linux: Yes
>	Multitasking:  Win95: Barely-Yes, Linux: Yes
>	Other hardware:  Win95:  Yes, Linux: Some

>	Video Capture for robotic sight:  Windoze95: Yes, Linux: Probably not

Just did a quick search of the Linux Software Map (LSM) and found lots 
of Linux software for use with frame grabbers. Software is listed for
still and motion video devices including Cortex I, ImageNation CX100,
ProMovie Studio card, PCTV1000, Video Blaster, WinVision card, Screen
Machine II, Matrox Meteor, Data Translation DT2851, and others. They also
listed mpeg and mpeg2 codecs, and CUSeeMe stuff - for when GARP gets
enough donations to buy that IP address :-)  


>5.  Maintenance:
>	Win95:  Next to none.
>	Linux:  Constant tinkering with the kernal.

If you're running a stable, release version of Linux, you shouldn't need
to recompile the kernel any more frequently than you have to download
patches for the Win95 kernel.  The difference is that Linux offers you
the option of tinkering with the kernel if you want to whereas Win95
doesn't.

>6.  Familiarity of the OS amoung the Group:
>	Win95:  Almost everyone
>	Linux:  Just A few

Valid point but if we plan to use the high-level portable languages
mentioned above (Tcl/Tk, C, etc.) being familiar with the internal 
workings of the OS isn't going to matter as much as being familiar
with the language. printf("hello world\n"); works on both of 'em...
And when it comes to programming the OS-specific points, I use so
many different ones at work I have to look that stuff up in the
manuals anyhow.

>8.  Speed:
>	Granted, Windoze will be slower than Linux most of the time,
>	but is it a significant difference for the various operations
>	we expect GARP to be able to do (movement, arm movement, video
>	processing, etc.)

The only danger I see is relying on Win95 for multi-tasking - it
just can't do it.  It's designed to switch between tasks like a word 
processor and a spreadsheet without crashing too frequently but it's
not designed to be a real-time OS.  Even MS warns companies not to 
use it for anything they consider "mission critical".  Here's a good
test we use to compare the smoothness of multitasking on various OS'.
Make a batch file or script that does a recursive dir ("dir /s" under
dos/windows) and then calls itself recursively.  Open up 4 or 5
command prompt windows and start up the batch file in the root in
each one.  On a smoothly multitasking OS like linux, OS/2, or even
NT you'll see the various processes scrolling by consistently.  On
Win95 you'll frequently see them moving for weird, unpredictable
amounts of time at varying speeds (assuming you don't cause a GPF
or something).  If that isn't enough, try printing, downloading a file,
or formating a disk at the same time (note don't try this on a machine
you haven't backed up recently!) If we've got Garp, say, operating
steering servos, measuring the distance to the nearest obstacle, and
articulating it's arms all at the same time, it's may be difficult to
get consistant results under Win95 (not impossible, perhaps - we could
boost the priority of the robot tasks above everything else or declare
critical code sections to get around the problem).  What we have to
consider is a modest learning curve for those who haven't used a unix
system vs. a lot of extra programming work to make GARP work well under
Win95.

>I talked with a guy in the Linux Users Group this weekend about some
>of our issues with Linux.  Of course, they'd like for us to use Linux

Ask him about the real-time version of Linux that was being worked on.
I heard about it a while back but haven't kept up with it.  It was 
supposed to be a very lean version of the kernel designed for real-time
and embedded applications.  Might be ideal for us.

You'll never get everyone to agree on the ideal OS but, whatever we
end up with will be usable, I'm sure.  One thing that might be worth
doing is take a survey of who thinks they might actually be writing
any of GARP's software and just have them vote on it.  Everyone's got
an opinion on the OS but I bet we won't all be writing software for
it... :-)

- -Steve


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