From:	"Chris Davis" <cjdavis@t-systems.com>
To:	"Linux-Embedded" <linux-embedded@waste.org>
Subject: A new "Linux SBC" proposal
Date:	Wed, 6 May 1998 16:08:06 -0700

Greetings fellow embedded Linux subscribers,

I work for a small company, Technologic Systems, that designs and
manufactures single board computers. I have been watching the discussion on
the embedded Linux list about doing a custom "Linux SBC" for the last month
or so, and have wanted to see what we could do.

Our current 386EX based boards are fixed at 2MB of system DRAM, which has
ruled out my getting Linux running on them. Fortunately, we began work
recently on a new board with the critical feature necessary - a 72 pin SIMM
socket. I have managed to convince the rest of the design team that adding
the features necessary to run Linux on our new SBC would be a Very Cool
Thing to do. Board layout is in progress now, and will probably be completed
in the next week or so. A limited production run should be available in
roughly 4 to 6 weeks.

Here is the major problem that I am looking for help on: the ~800K flash
disk that our current SBCs have works just fine for our customers writing
software for DOS, but won't cut it for a Linux system. But just how much
storage space is needed? (My own experience with Linux has been on
comparatively huge desktop machines.) Looking at the Linux Router Project
makes me think that ~1.2 MB is an absolute minimum (so close!) but that 2 MB
would work ok. Is this about right?

Various options that come to mind:

* The board will have a socket for the DiskOnChip 2000. Are there Linux
  drivers for the DiskOnChip? I have seen no mention of them, and the
  price of adding one can be prohibitive -- we currently have the 4 MB
  size for sale around $90, which is almost half the price of the board
  itself.

* Adding another 1 MB of basic flash, bringing it to just under 2 MB. But
  once again, I have not seen a flash disk driver for linux. The BIOS
  has native support for the flash disk as an INT 13h device, but that's
  not going to do any good for Linux. Or is it?

* Adding an IDE interface, which opens access to a wide range of devices -
  hard disks, flash disk, zip drives, floptical drives, even cdrom..
  This might be the best idea - drivers are all standard, for example. And
  the prices I just saw on this list for the SanDisk pulls were not bad at
  all.

Currently, the major feature list for our "Linux SBC" is as follows:

* 25Mhz i386EX processor
* 72 pin SIMM socket - will accept 4 MB, 16 MB, or 32 MB SIMMs
* 8-bit PC/104 bus
* 32 pin socket for DiskOnChip 2000, or battery backed SRAM
* General Software BIOS and DOS-ROM
* ~800K flash disk with BIOS support
* 2 serial ports, RS-232 or RS-485/422
* Parallel printer port (8 data + strobe out, 8 in)
* Interface for an alphanumeric LCD display
* A 'programmable I/O' area. This will consist of a programmable logic
  device and header which can be customized for different uses by simply
  programming the PLD (a MACH 120 or MACH 220 specifically) with new
  equations. The board will probably ship standard with a full
  bi-directional parallel port implemented. Other uses might include:
	* an Opto-22 interface
	* an 'input parallel port' for a customer doing data filtering aps.
	* an IDE interface! (maybe..)

* Quantity one pricing is currently looking like ~$190 with a 4 MB SIMM.

At this point, I am looking for ideas on just how to implement inexpensive
non-volitaile storage under Linux. If this goes well, we will build on this
design for future products -- adding an ethernet interface, for example.

For those who are interested, this board will be very similar to our TS-2325
product. Info and the full manual are available on our web site. The web
site is a bit anemic, but we are slowly adding to it as time permits.

	http://www.t-systems.com/

Thanks,
Chris Davis
cjdavis@t-systems.com

---------------------------------+-------------------------
Chris Davis, Technologic Systems | voice:  (602) 837-5200
16610 East Laser Drive Suite 10  | fax:    (602) 837-5300
Fountain Hills, AZ 85268         | web: www.t-systems.com