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Date:      Fri, 21 Jul 2000 14:47:07 -0600
From:      Warner Losh <imp@village.org>
To:        norami@unlimited.net
Cc:        Gunther Schadow <gunther@aurora.rg.iupui.edu>, freebsd-small@FreeBSD.ORG
Subject:   Re: are there any *inexpensive* SBC with just the right features? 
Message-ID:  <200007212047.OAA02675@harmony.village.org>
In-Reply-To: Your message of "Fri, 21 Jul 2000 13:42:51 PDT." <3978B5CB.F920A0DA@unlimited.net> 
References:  <3978B5CB.F920A0DA@unlimited.net>  <397885FD.40281ADE@aurora.rg.iupui.edu> 

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In message <3978B5CB.F920A0DA@unlimited.net> John Oram writes:
: > - CPU i486 or i586 100 - 200 MHz is just fine
: > - VGA is *not* required at all, instead I want
: > - on board Ethernet 10/100 at least one interface,
: >   some would even need two

two is a problem.

: > - one or two SIO ports, one or two LPT ports.
: > - CompactFlash ram (PCMCIA type is probably best at
: >   this time for it's easier to interoperate with.)
: > - IDE disks are not needed (if CompactFlash works
: >   and can be booted from.)
: > - really small form-factor
: > - low power consumption
: > - low heat production
: > - simple power requirements (e.g., 12 V DC only)
: >   (so that it can be fit into a small box with a simple
: >   external AC adapter.)
: > - low price <= $300 including i486 CPU, 32 MB RAM
: >   and 8 MB CompactFlash RAM.

For all of those, excpt price, the megatel boards are nice.  These are
a 2.5"x2.5" square board that's 1" thick.

: > I imagine the following problems:
: > - without VGA, debugging of system startup sequence will
: >   be a pain in the butt (nothing happens and you don't
: >   know why...)

serial consoles work great.  I use them all the time.

: > - the PCMCIA-based CF card is not the typical thing found
: >   on SBCs. Most have DiskOnChip kind of setup which is
: >   not too robustly supported by FreeBSD at this point.

That's not completely true.  We have some half height boards here from
teknor that have a CF saughter card.

DiskOnChip is well supported by FreeBSD.  We had bad luck with the
parts themselves, but I'm told that the supply problems we got caught
in have been fixed.

Also, there are lots of CF <-> IDE adapters out there.  Tapr
(http://www.tapr.org) has one, as does pcengines.  They run about
$20-$25 each.  You can use a desktop with a CF <-> PCCARD adapter to
burn them.  Works great now that I fixed the multiple insert bugs in
FreeBSD before 4.1.

: >   Furthermore DiskOnChip would raises a bootstrapping problem,
: >   i.e., how to get the first image onto the chip without one
: >   of those computers running already...

You can buy a card that lets you plug them into desktops.  Also, if you
have a passive bus backplane, you can plug an SPC into the bus and
install onto it.  Be warned you'll need to do some hacking to get a
small set of FreeBSD programs, either via the pico bsd rout, or
through hand rolled scritps like I have to build our CF and DOC
parts.

: > - noone will put 2 Ethernet interfaces on board and stacked
: >   PC104 cards turn into an unwieldy form-factor and PC104
: >   is quite expensive

True.  The ISA backplanes also have similar problems.

: > - my wishlist looks like custom - and custom is expensive.

It isn't all that custom.  You can find cards by Axiom and Teknor
might fit your needs.  Also, if you have to go very small, there's the
megatel board.

: > Anyone please offer any thoughts?

Good luck.  That second ethernet might kill you (or at least make
things expensive).  Your other option with the second ethernet might
eb to go USB, as the teknor card has USB built into it.  We don't use
it in our app, so I don't know how well/poorly it works.

Warner


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