EMC / BDI / Linux / RTLinux / RTAI confusion

--- In CAD_CAM_EDM_DRO@y..., Ray Henry <rehenry@u...> wrote:

>
> <snippage>
>
> A CD based real-time kernel should be easy enough but would
> probably need to be rtai rather than rtlinux since this is
> the latest debian distro.
>
> <more snippage>

Well, I just read over what I typed below, and I see that it
turned into a combination question/rant. Sorry - if you aren't
a Linux/ EMC person, stop here. If you are, please bear with
me, and perhaps point me in the direction of enlightenment.

Thanks - here goes....

I am a newbie to Linux & CNC, planning a Shoptask CNC conversion.
I have been reading webpages, etc. about Linux, real time Linux,
and EMC, but the more I read the more confused I get. I'm no
dummy, I have been a serious hobby machinist for 4+ years, have
20+ years of programming experience (including real time) and
work as an EE on motor drives. In fact, that's why I want to
use EMC - I want something that let's me get under the hood and
play around. In spite of all that, I was confused long
before Ray's post, and am even more confused now.

Here's my problem:

After reading all kinds of info on the web, including this board,
the NIST site, and many others, I still don't know what plays
with what. I understand that EMC runs under RTLinux, which is a
real time patch of the Linux kernel, which comes as part of a
distribution from Red Hat, SuSE, Debian, or others. BDI is a
disk containing a one version of one distro, with one version
of the kernel, carrying one version of RTLinux, and running one
version of EMC. Very convenient for folks like me who don't have
fast internet connections to D/L a whole CD-ROM worth of stuff.
However, I don't know _which_ versions of anything are on the
disk, and can't seem to find that info anywhere. Then there
is something called BDI TNG, which seems to have newer versions
of everything, but again I don't know which versions.

Does TNG replace the original BDI, or are they on parallel paths?
I've heard people here post that they are using old pre-BDI stuff
(RedHat 5.2, RTLinux 2.0?, kernel version 2.?, EMC version ?.?) to
make parts using relatively low end PCs, and other have said that
you need lots of speed and RAM to use TNG. Are the demands of the
software really getting worse with each new version? Avoiding
bloat is one reason I _don't_ want to use Windoze, please don't
tell me bloat is taking over in Linux land too.

More version confusion - The rtlinux.org site linked to by
NIST and others is now gone, redirected to a commercial company
run by the same folks called FSMLabs.com. They are now delivering
RTLinux 3.0, which supposedly has a different API than 2.0, and
all traces of RTLinux 2.0 seem to have dissappeared. Meanwhile,
RedHat is now shipping version 7.something, kernels range from
2.0 to 2.4, and I haven't the slightest idea what is the current
version of EMC. And now Ray is mentioning RTAI. I thought RTAI
was a competing, and non-compatible, real time alternative
to RTLinux.

So if I want to set up a CNC machine, and want a programming
environment for real time programming, what do I do? Do I stick
with old reliable software (RH 5.2, RTLinux 2, etc.) if I can
find it, and accept that the world is passing me by and I'm
coding to an obsolete API, or do I get the latest and greatest
and try to find more powerful machines to run it on?

Is there some website or document out there that I just haven't
found yet that is going to enlighten me? Or is my situation
(confused) the norm....

Here's what I have right now:

1) Old HP Vetctra, originally P5/100, upgraded to P5MMX/233,
64M ram, 1.7G HD, dual boot WIN95B and Red Hat 6.0, kernel
2.2.15 - my Linux sandbox. I did the dual boot install,
not anywhere as bad as I'd been led to believe. I've
played around with Linux command line basics, written
and compiled "Hello, World", etc. One of these days I'll
rebuild the kernel, maybe that is a rite of passage and
all will be made clear to me. <yeah, right> Nothing on
that machine is critical, so I can hack to my hearts
content.

2) Not quite so old Gateway, P5/233, 64M RAM, 4G & 2G hard
disks. Currently running Win95B, partitioned with half
of each disk reserved for Linux. I've got RH6.0 & RH7.0
CDs, and I could buy BDI, but no Linux is installed there
yet - I need to get un-confused first. This machine will
be my drafting/office PC - on the Win95 side it will run
EasyCad (a great program), and other general purpose
programs. It is the one that I will sit down in front of
to write programs (both g-code and computer programs).
I really don't want to have to re-install on this machine.
Right now it's kinda empty, but it will eventually fill
up with apps and data and be a major pain to rebuild.

3) Allen Bradley model 8160 Industrial PC - saved from the
scrapheap at work. P5/200, 64M RAM, 4G HD, 14" 800x600 LCD
display, and membrane keypad, all in a chip- and oil-proof
box, with connectors for a conventional keyboard and mouse if
needed. This one will be the machine controller, mounted
next to the Shoptask. I have network cards for all three
computers, and plan to connect them so I can move programs
from the drafting computer to this one. All the hardware
works, the hard disk has been wiped and is awaiting the
gentle touch of FDISK and format/diskdriud....
I'm getting good at putting together PC's if nothing else!

Thanks for your patience,

John Kasunich