Almathera Ten Pack 3: CDPD 3/Almathera Ten on Ten - Disc 3: CDPD3.iso/scope/051-075/scopedisk55/muserial/multiserial

Text File | 1995-03-19 | 12.1 KB | 329 lines

CS-ID: #13336.amy/amynet@pro-pac 8442 chars
Date: Fri,  3 Feb 89 06:44:08 HST
From: [e-mail] (Bryce Nesbitt)
Subject: Multiple serial article from the European Developer's Conference

--------------------------------------------
-- Amiga Multiple Serial Ports: User View --
--------------------------------------------


Software
--------

The current version of the Amiga has only one serial port.  Since many
devices can interface with a serial port, having more serial ports is an
obvious improvement.

New system software has been developed for the Amiga which will allow
plug in cards with extra serial ports to be used.   A typical setup on a
four port machine might be:

        Port 1 - Connected to a MIDI keyboard
        Port 2 - connected to a modem
        Port 3 - connected to a printer
        Port 4 - connected to a home-control device

Extra serial ports will also allow applications such as a multiple line
bulletin board system (BBS) with several modems connected to a single
computer.  Such a BBS could support simultaneous users.



Multiple serial ports are implemented in a way which is compatible with
existing software.

    o  Old applications that ask for the serial port will be given
       the "default" port.  Using the Preferences tool, the user will
       be able to set the default to any valid port.

    o  New programs will provide a way for the user to select the serial
       port to use.   If the user selects the number "0" or the word
       "default", the program will connect to the default port which is set
       in Preferences.  The built-in port is unit 1.  Extra serial ports
       are numbered from two upward.

    o  From BASIC and the CLI, ports may be directly accessed in the
       same manner as works today:

                    SER:    = the default port
                    SER1:   = the built-in port
                    SER2:   = the second port
                    SER3:   = the third port
                    SER4:   = the fifth port




Hardware
---------

In addition to the new software support, Commodore is developing a plug in
card with multiple serial ports.  All Commodore multiple serial port cards
will have a simple installation procedure:

    o  Insert the serial card into a slot.
    o  Boot up with the normal Workbench disk or hard drive.
    o  Insert the disk that comes with each serial card.
    o  Double click on the "Install Drivers" icon.
    o  To remove a driver, double click on the "Remove Drivers" icon.

Any number of cards may be installed.  Advanced users may install the
driver software manually instead of using the installation icon.

Commodore's design for matching ports on cards with unit numbers is simple.
Port number 1 is the serial port built into each Amiga.  Higher port numbers
indicate extra serial ports the user has added with a plug in card.
The bottom plug on a card is given the lowest unit number.



---------------------------------------------------
--- Amiga Multiple Serial Ports: Device Driver  ---
---------------------------------------------------

A Commodre support document will be available for people who wish to write
multiple serial port device drivers.  The document is available by request
only.  We may send updates to the document, and require the name and
address of a contact person.

To request the support document, send your name, address, telephone number
and a short description of your hardware to:

            CATS
            Commodore Business Machines
            1200 West Wilson Drive
            West Chester, PA  19380-4231
            USA


------------------------------------------------------
--- Amiga Multiple Serial Ports: Programmer's View ---
------------------------------------------------------

If you are writing serial port applications for the Amiga, you can now
add support for multiple serial port cards.  This is easy to do and
will give your program extra power.

On an Amiga with one serial port the code needed to open the serial port
looks like this:

    error = OpenDevice("serial.device", 0, myIORequest, 0);
    /*
     *      BYTE=OpenDevice(char *,ULONG,struct IORequest *,ULONG);
     *
     *      "serial.device" = name of the device
     *      0               = unit number (unused)
     *      myIORequest     = a blank extended trackdisk IORequest
     *      0               = flags (unused)
     */


To work with multiple serial ports, just one very simple addition is
required:

    error = OpenDevice("serial.device", myUnit, myIORequest, 0);
    /*
     *      BYTE=OpenDevice(char *,ULONG,struct IORequest *,ULONG);
     *
     *      "serial.device" = name of the device
     *      myUnit          = which unit to try and open
     *      myIORequest     = a blank extended trackdisk IORequest
     *      0               = flags (unused)
     */

Notice that the second parameter has changed.  Under the old system, unit
number was always set to 0.  Now the unit number is used to identify
which of the serial ports should be used.  The unit assignments are:

    Unit 0  =   default port, settable from Preferences
    Unit 1  =   the built-in serial port
    Unit 2  =   the first extended unit
    Unit n  =   last extended unit

System support for a multiple port serial card requires changes to some of
the system files on disk.  These files have been changed:

        devs:serial.device      ;exec support
        l:port-handler          ;AmigaDOS support
        Preferences             ;default port selector buttons


User Interface
--------------

Your application must allow the user to set the unit number.  There are
several ways to do this.

   o  Use the TOOLTYPES field of the icon.  Each icon has a
      TOOLTYPES field which you can fill in with UNIT=0.
      The user can modify the number later if needed.  You
      could also go one more step, and add DEVICE=serial.device
      to this field.

   o  Have an option that brings up a box with a "default" gadget
      and a string gadget for typing in a number.


   o  Add a menu or submenu like this:

        ---------------
        |             |
        | unit number |
        |         -----------
        ----------| default |
                  |    1    |
                  |    2    |
                  |    3    |
                  |    4    |
                  |*   5    |
                  |    6    |
                  |    7    |
                  |    8    |
                  -----------

      There are two disadvantages to this method.  First, you
      cannot find out how many units are connected with the
      current serial.device.  Second, the number of ports
      available could exceed the vertical size of a menu.



Future Design Issues
--------------------

Plans for the V1.4 serial.device include several sensible extensions to the
current command set.  For example, the best way to read under the current
serial.device is:

    o  Send a CMD_QUERY to see how many bytes are in the buffer.

    o  If there are any bytes, get them ALL with a CMD_READ.

    o  Else post a CMD_READ for exactly one byte.  When it returns,
       loop back to step #1.


With the old serial.device, this was the only way to get acceptable
performance at high baud rates.  With the new serial.device, one will be
able to set a bit to request all available bytes from the serial port
(up to the size of the user buffer).  The request will be held by the
device until at least one byte is ready.

The OpenDevice() call does not support a version number check at present.
In most cases there is no need to check the version number since the new
serial device is backward compatible.  However, if you do need to find the
version number of the serial device, you should first open the device and
then look at the LIB_VERSION word in the device base.  Versions 36 and higher
support multiple ports.  Versions 35 and lower ignore the unit number field.

The Amiga's built-in serial port can generate any baud rate in the range
108 to 1,000,000 baud.  However, off-the-shelf serial chips usually only
support the standard rates such as:

             110      600       9600
             150     1200      19200
             300     2400      38400

Also, standard serial chips usually do not support the MIDI baud rate (31250).
Since most multiple serial port cards will be using standard serial chips,
the extra ports will not support all the different baud rates that the
built-in serial port does.  There is no way for a serial.device client to
find out the capabilities of a specific serial unit at present.



|\_/|  . ACK!, NAK!, EOT!, SOH!
{o O} .     Bryce Nesbitt
 (")        BIX: bnesbitt
  U         USENET: cbmvax![e-mail] -or- rutgers!cbmvax!bryce
CS-ID: #13339.amy/amynet@pro-pac 739 chars
Date: Fri,  3 Feb 89 06:44:28 HST
From: [e-mail] (Shawn Clabough)
Subject: Re: 68020 boards

I have a short benchmark that I ran using my old Processor Accelerator
benchmark.  It plots two sine waves on the screen and displays how long
it took to complete.  In standard 68000 mode it took 51.3 seconds to
complete.  With my A2620 in 68020 mode it took 1.5 seconds (yes 1.5).
The program was compiled with the 1.3 IEEE libraries, so it took
advantage of the 68881.  I imagine that if this program was written with
inline code for the 68020/881 it would be even faster.

How much do the A2620's cost?  I'm selling them for $1575 (retail $1995)

                                        Shawn Clabough
                                        Lombards Underground Computers
                                        [e-mail]


CS-ID: #13345.amy/amynet@pro-pac 2544 chars
Date: Fri,  3 Feb 89 06:44:55 HST
From: [e-mail] (Perry Kivolowitz)
Subject: Re: Serial Ports

Kim,

Your facts are all basically correct concerning the serial port solution
provided by the Twin-X General Purpose I/O board. Let me clarify a few
points:

The list prices are:

Twin-X board (supports 2 modules): $329
SBX-Serial/2 (dual serial ports):  $199
SBX-Serial/4 (quad serial ports):  $299 * you might have missed this one.

There's also

SBX-GPIB     (ieee-488 interface): $199

You might have missed the information on the SBX-Serial/4 which will
allow up to eight serial ports on one Twin-X card.

I agree with you that the general approach of the Twin-X concept comes
with some added cost. Our goal was to be able to make the Amiga available
to many hundreds of different input/output modules with one broad stroke.
It is true that while providing the capability for adding rather esoteric
i/o functions, we've caused the price of basic i/o functions to be a little
higher (do keep in mind the average discount a dealer gives so the prices
are actually a little lower).

Wouldn't it be nice though to be able to combine an esoteric function like
a VPI interface (Versatec Plotter Interface) with a 16 bit a to d converter
for that otherwise impossible application your boss may have just handed
you? Or maybe you need a stepper motor controller and a 32K static battery
backed up ram module. Or......

It is no secret that ASDG has always provided industrial grade equipment (as
opposed to consumer grade). And, we've never pretended our hardware products
were the cheapest, either.

It is also no secret that we aren't consumer oriented when it comes to hardware
(software is a different side of our business altogether). We
certainly don't entertain any false hopes of going one on one with consumer
oriented producers competing solely on a basis of price. Especially with a white
bread type function as serial ports.

But then... we do have the advantage of being first you see. And another
advantage of high reliability and performance. So there'll be a large
amount of consumer sales of even this product. When these advantages are
gone (perhaps in 6 to 12 months) we still have our primary customer who
requires some extra serial ports AND an i/o function that only Twin-X
can provide.

So, in summary...sure our serial port solution might be higher in cost
than some. But then again...its available now...and it works.

See ya.

Perry

--
Perry Kivolowitz, ASDG Inc.

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