SUMMARY: serial expanders

From: Steve Harris (etnibsd!vsh@uunet.UU.NET)
Date: Wed May 06 1992 - 15:32:46 CDT

Sun Managers,

Sorry for the long delay in summarizing, I wanted to make sure there
were no "straggler" responses, and then I was swamped by a series of

My original request was:

> We are looking to add additional serial ports to our IPCs.
> We have been using the Sun "Serial Parallel Controller", but have had
> problems with this product. In addition, it ties up an Sbus slot.
> We are looking for alternatives to this product, particularly (but not
> exclusively) those that do not use the Sbus. We know about at least
> one SCSI-bus based serial extender, from Central Data.
> If you have had experiences, good or bad, with this or any other serial
> expander product, I would be most interested in hearing about them.

Responses came in four flavors:

    Sbus-based expanders (and Sbus expander)
    SCSI-bus-based expanders
    Serial multiplexers
    Ethernet terminal servers

Because our requirements are perhaps somewhat unique, the terminal
server is not a viable option, and the Sbus expander is probably not
cost effective. Consequently, I did not dig for more info than was
emailed to me. I've included what info I have in the summary.

A thorough survey would include individual and aggregate throughput
specs. However, because bandwidth is not crucial to our application, I
have not dug for those data points.

A thorough survey would also include whether or not the serial ports
support: full modem control, synchronous RS-232-C, RS-422. Maybe one
of the mags (Sun World/Expert/Observer/...) will fill in the blanks.

We have not determined what route we will take. Next step will be to
evaluate the SCSI-bus expanders and the serial multiplexer. If that
becomes a priority (i.e., when it becomes a crisis ;-) and we actually
get around to doing it, I will post a further summary.

Thanks to everybody who responded.

If anybody wants a copy of ALL the email I received (56K bytes), I will
be happy to forward it.


Format of summary:

    Vendor: name of vendor
    Address: address of vendor
    Phone: phone number of vendor
    Fax: fax number of vendor
    Contact: contact persons at vendor
    Product: name, type, or general description
    Ports: s/p, s/p, ...
    Ref from: non-vendor respondents that mentioned product
    Notes: my comments

re: Ports info: s/p => number of serial/parallel ports
                s/p ... s/p => indicates endpoints of range of products


Sbus-based expanders

    Vendor: Sun Micro
    Phone: 800-USA-4Sun
    Product: SPC (Serial Parallel Communications card)
    Ports: 8/1
    Notes: kit was uprev'ed without notification,
                kernel with old driver does not work with new unit :-(

    Vendor: Aurora Technologies, Inc.
    Address: 176 Second Ave.
                Waltham MA 02154
    Phone: 617-290-4800
    Fax: 617-290-4844
    Contact: Jeff Martin (
                Steve Valencia (
    Product: family of serial expanders, and Sbus expander
    Ports: 16/0, 8/0, 4/0, 2/1, 0/1, 0/2
    Ref from: David Gunn (ldavis!
    Notes: suggest using Sbus expander

    Vendor: GNP Computers
    Phone: 818-577-4252
    Product: DEI
    Ports: 8/1 ... 32/4
    Ref from: John Uhley (
                Kevin Sheehan (uunet!fourx.Aus.Sun.COM!kalli!kevin)
    Notes: Uhley wrote driver for GNP,
                Kevin is happy with his unit

    Vendor: Artecon
    Phone: 800-USA-ARTE
    Product: family of serial expanders, Sbus expander
    Ports: 3/? ... 16/?
    Ref from: Brian Woodson (

SCSI-bus-based expanders

    Vendor: Central Data
    Address: 1602 Newton Drive
                Champaign IL 61821
    Phone: 800-482-0315
    Fax: 217-359-6904
    Product: family
    Ports: 2/1, 8/1, 16, 0/3, ... 392/49
    Ref from: stephen dowdy (
                Jeff Crilly (
                Russ Poffenberger (
                Don Mac Leod (
    Notes: well liked, easy to install, "it works"
                old driver sometimes failed to see unit at boot time

    Vendor: Uninet Peripherals, Inc.
    Address: 17981 Skypark Circle, Suite O
                Irvine, CA 92714
    Phone: (714) 263-4222
    Fax: (714) 263-4299
    Contact: Neil Gorsuch (uunet!uninet!neil)
    Product: SLAT -1, -2, -3, -4 (families of serial expanders)
    Ports: many combinations, incl: 0/1, 0/2, 4/1, 8/1, 12/1, 16/0
    Notes: serial ports are RJ45 (DB25 adapter available)
                parallel ports are DB25
                other parallel interfaces: Data Products, DRV11-J, Versatec
                No special device driver needed, unit emulates SCSI disk!!!
                    (daemon process services I/O requests via ptys)
                Working on a high-end unit (~500000 cps aggregate)

Serial multiplexers

    Vendor: Vector Technologies
    Address: 3289 E. Hemisphere Loop
                Tuscon, Arizona 85706-5028
    Phone: (602) 741-0120
    Fax: (602) 889-5790
    Ports: 14/2
    Ref from: Marcel Bernards (Bernards@ECN.NL)
    Notes: ref. from co-worker (no direct experience)
                aggregate bandwidth must be limited by max
                    bandwidth of Sun serial port

Ethernet terminal servers

    Vendor: Xyplex
    Ref from: Brent A. Wiese (
                Jim McManus (uunet!Think.COM!jjm)
    Notes: Brent is happy with his unit,
                Jim is evaluating one

    Vendor: Xylogics
    Product: Annex 3
    Ports: 8/? ... 64/?
    Ref from: Stuart McRobert (uunet!!sm)
    Notes: "integrates into unix well (tip, cu, printing software work fine)"

.. Steve Harris - Eaton Corp. - Beverly, MA - uunet!etnibsd!vsh

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