






















                                  USERS MANUAL

            SIO.SYS and VSIO.SYS, Serial Communications Device Driver
            for OS/2 V2 (and up) and its Virtual DOS Machines (VDM).

                     Copyright (c) 1995 by Raymond L. Gwinn
                              12469 Cavalier Drive
                           Woodbridge, Virginia 22192
                               All Rights Reserved

                                January 27, 1995

                                      Email
                              CompuServe 71154,575
                             Internet ray@gwinn.com

                           VOICE ORDERS 1-703-494-4673
                               FAX 1-703-494-0595
                       BBS 1-703-494-0098 or 199.248.240.2






















                                  INTRODUCTION

     SIO.SYS and VSIO.SYS are companion device drivers for Version 2 (and
     up) of the OS/2 operating system.

     Both drivers (SIO/VSIO) have been coded with performance in mind,
     possibly sacrificing some compatibility.  For this reason, SIO and
     VSIO are not exact replacements for the OS/2 drivers COM and VCOM. 
     However, all serial communications programs tested by the author work
     correctly using SIO/VSIO.

     This manual is intended for the SIO user.  A separate SIO Technical
     Reference Manual is included in the distribution zip.  The Technical
     Reference Manual also documents some advanced options and features
     that are not documented here.

     This manual and the software distributed with it is provided with no
     guarantees.  Use it at your own risk.




                                                                         ii

                                TABLE OF CONTENTS


     INTRODUCTION  . . . . . . . . . . . . . . . . . . . . . . . . . .    i
          SIO Technical Reference Manual . . . . . . . . . . . . . . .    i

     WHAT IS SIO . . . . . . . . . . . . . . . . . . . . . . . . . . .    1

     WHAT IS VSIO  . . . . . . . . . . . . . . . . . . . . . . . . . .    2

     DISTRIBUTION AND SUPPORT  . . . . . . . . . . . . . . . . . . . .    3
          Distribution and Ordering  . . . . . . . . . . . . . . . . .    3
               SIO Distribution and Support BBS  . . . . . . . . . . .    3
          Support  . . . . . . . . . . . . . . . . . . . . . . . . . .    3
               OS/2 Vendor Forum on
                    CompuServe . . . . . . . . . . . . . . . . . . . .    3
          Updates  . . . . . . . . . . . . . . . . . . . . . . . . . .    4

     GETTING STARTED . . . . . . . . . . . . . . . . . . . . . . . . .    5
          Installing SIO/VSIO  . . . . . . . . . . . . . . . . . . . .    5
          Quick Start  . . . . . . . . . . . . . . . . . . . . . . . .    5

     COMMAND LINE OPTIONS  . . . . . . . . . . . . . . . . . . . . . .    6
          COM1 thru
               COMn  . . . . . . . . . . . . . . . . . . . . . . . . .    6
          I/O port address . . . . . . . . . . . . . . . . . . . . . .    6
          IRQ number . . . . . . . . . . . . . . . . . . . . . . . . .    6
          Forced 16550A  . . . . . . . . . . . . . . . . . . . . . . .    6

     Development and Debugging Tools . . . . . . . . . . . . . . . . .    8
          The Poor Man's Line Monitor (PMLM.EXE) . . . . . . . . . . .    8
          VIEWPMLM.EXE . . . . . . . . . . . . . . . . . . . . . . . .    9
          SIO's Utility (SU.EXE) . . . . . . . . . . . . . . . . . . .    9
               IRQs that are currently free  . . . . . . . . . . . . .    9

     Intelligent Cards Supported . . . . . . . . . . . . . . . . . . .   10
          Hayes ESP  . . . . . . . . . . . . . . . . . . . . . . . . .   10
               ESP in Compatibility Mode . . . . . . . . . . . . . . .   10
          Telcor Tport . . . . . . . . . . . . . . . . . . . . . . . .   10

     . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   11

     AUTOMATIC IRQ ASSIGNMENT  . . . . . . . . . . . . . . . . . . . .   11

     DOS SETTINGS  . . . . . . . . . . . . . . . . . . . . . . . . . .   12
          SIO_Allow_Access_COMn  . . . . . . . . . . . . . . . . . . .   12
          SIO_Virtualize_COM_Ports . . . . . . . . . . . . . . . . . .   12
          SIO_Virtualize_16550A  . . . . . . . . . . . . . . . . . . .   12
          SIO_Share_Access_With_OS/2 . . . . . . . . . . . . . . . . .   12
          SIO_Screen_Sync_Kludge . . . . . . . . . . . . . . . . . . .   13
          SIO_Mode_DTR . . . . . . . . . . . . . . . . . . . . . . . .   13
          SIO_Mode_IDSR  . . . . . . . . . . . . . . . . . . . . . . .   14
          SIO_Mode_OCTS  . . . . . . . . . . . . . . . . . . . . . . .   15
          SIO_Mode_ODSR  . . . . . . . . . . . . . . . . . . . . . . .   15
          SIO_Mode_RTS . . . . . . . . . . . . . . . . . . . . . . . .   15




                                                                        iii

          SIO_Mode_XON/XOFF  . . . . . . . . . . . . . . . . . . . . .   16
          SIO_Mode_FIFO_Load_Count . . . . . . . . . . . . . . . . . .   17

     Configuration Profiles  . . . . . . . . . . . . . . . . . . . . .   18
          Seiko Smart Label Printer  . . . . . . . . . . . . . . . . .   18
          IBM's SLIP . . . . . . . . . . . . . . . . . . . . . . . . .   18

     Differences between SIO/VSIO and COM/VCOM . . . . . . . . . . . .   19

     PROBLEMS AND SOLUTIONS  . . . . . . . . . . . . . . . . . . . . .   21
          IRQ for a port appears to be wrong . . . . . . . . . . . . .   21
          The modem will not initialize  . . . . . . . . . . . . . . .   21
          WinFax locks up during install . . . . . . . . . . . . . . .   21
          Telemate does not recognize VX00 as a FOSSIL . . . . . . . .   21
          Comm output is very slow from DOS  . . . . . . . . . . . . .   21
           . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   21
          Procomm stops receiving  . . . . . . . . . . . . . . . . . .   22
          WinFax does not work well. . . . . . . . . . . . . . . . . .   23
               Class 1 FAX modem . . . . . . . . . . . . . . . . . . .   23
               Class 2 FAX modem . . . . . . . . . . . . . . . . . . .   23
          Serial Printer messes up on last page. . . . . . . . . . . .   23

     IRQ SHARING ON ISA  . . . . . . . . . . . . . . . . . . . . . . .   24

     Appendix A, Hardware Port and IRQ Assignments . . . . . . . . . .   25
          Addresses and IRQs for COM1 and COM2 . . . . . . . . . . . .   25
          Defacto standard for COM3 and COM4 . . . . . . . . . . . . .   25
          Addresses and IRQ for COM3 through COM8 on the PS/2  . . . .   25

     Appendix B, SIO Chips . . . . . . . . . . . . . . . . . . . . . .   26
          8250 . . . . . . . . . . . . . . . . . . . . . . . . . . . .   26
          8250A  . . . . . . . . . . . . . . . . . . . . . . . . . . .   26
          16450  . . . . . . . . . . . . . . . . . . . . . . . . . . .   26
          16C451 . . . . . . . . . . . . . . . . . . . . . . . . . . .   27
          16550 (Non A)  . . . . . . . . . . . . . . . . . . . . . . .   27
          16550A . . . . . . . . . . . . . . . . . . . . . . . . . . .   27
          16550AF  . . . . . . . . . . . . . . . . . . . . . . . . . .   27
          16550AFN . . . . . . . . . . . . . . . . . . . . . . . . . .   27
          16550s Made by Western Digital . . . . . . . . . . . . . . .   28
          16C551 . . . . . . . . . . . . . . . . . . . . . . . . . . .   28
          16C552 . . . . . . . . . . . . . . . . . . . . . . . . . . .   28
          16C554 . . . . . . . . . . . . . . . . . . . . . . . . . . .   28
          82510  . . . . . . . . . . . . . . . . . . . . . . . . . . .   28
          16650  . . . . . . . . . . . . . . . . . . . . . . . . . . .   29
          ComBic . . . . . . . . . . . . . . . . . . . . . . . . . . .   30

     Appendix C, Multi-Port Serial I/0 Cards . . . . . . . . . . . . .   31
          STB 4COM . . . . . . . . . . . . . . . . . . . . . . . . . .   31
          Connect Tech Dflex-8 . . . . . . . . . . . . . . . . . . . .   31
          Gtek BBS550  . . . . . . . . . . . . . . . . . . . . . . . .   32
          Neotech Quad Serial  . . . . . . . . . . . . . . . . . . . .   32

     INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   33




                                                                          1

                                   WHAT IS SIO

     SIO is a Serial Input/Output (SIO) communications driver.  It provides
     an interface between application programs and the serial
     communications hardware.

     SIO had been designed as a high performance replacement for the OS/2
     device driver COM.SYS.  See the Technical Reference Manual for
     information about the known differences between COM.SYS and SIO.SYS.

     SIO works with 8250 (type) serial I/O devices.  Such devices include,
     but are not limited to the 8250A, 16450, 16550, 16550A and the 82510. 
     If you have a PC that is an IBM or near compatible which has a serial
     communication port, it is likely that it contains one of these
     devices.  In addition, SIO supports some intelligent serial I/O cards. 
     See "Intelligent Cards Supported" for additional information.  SIO
     will identify the type of serial devices that it finds and display
     them at load time.

     Like other Device Drivers, SIO will do very little standing alone. 
     There must be an application(s) program that makes use of SIO's
     functions before one will benefit from SIO.




                                                                          2

                                  WHAT IS VSIO

     VSIO is a Virtual Device Driver (VDD).  Virtual device drivers provide
     services for DOS programs executing under OS/2.  Most Virtual Device
     Drivers emulate a specific hardware device and/or BIOS service.  The
     primary job of a Virtual Device Driver is to convert misbehaved DOS
     input/output into well behaved input/output that can be accepted by
     the OS/2 driver SIO.SYS.

     Using the protection mechanism of the 386 (and up) processor, a
     Virtual Device Driver can instruct OS/2 to trap all input/output for
     given hardware ports.  Once trapped, the Virtual Device Driver (VDD)
     appropriately routes information to/from the Physical Device Driver
     (PDD) and to/from the DOS program.

     VSIO creates a virtual (imaginary) 16550A or 16450 (UART) in software. 
     Additionally VSIO emulates the BIOS INT 14h services.  All of the
     hardware registers of the virtual UART are simulated by VSIO.  VSIO
     does not attempt to simulate the timing of the real UARTs.  DOS
     programs that depend on the timing of real hardware UARTs may have
     problems executing under VSIO.

     All DOS programs that execute under VSIO should have RTS/CTS
     handshaking enabled (in the application) even if SIO proper is not
     using RTS/CTS handshake.  

     The virtualization (simulation) provided by VSIO is not (and can not
     be) exact.  However, most well written DOS programs should not have
     problems.

     VSIO will only work with SIO installed and the versions of SIO/VSIO
     must match.  If VSIO refuses to install, you most likely have a
     version mismatch or COM.SYS is still installed.  VSIO will not work
     with any other device driver like COM.SYS.




                                                                          3

                            DISTRIBUTION AND SUPPORT

     Distribution and Ordering
     The entire package collectively known as SIO is ShareWare.  It is not
     free software or freeware.  See LICENSE.TXT and ORDER.TXT for
     additional information.  The ShareWare version of SIO is distributed
     electronically and supports only 4 ports (registered versions can be
     ordered supporting up to 16 ports).  One may check their favorite
     electronic hangout for the latest version of SIO.  The latest copy of
     the ShareWare version is always posted for downloading from the BBS at
     1-703-494-0098 or 199.248.240.2.

     Registered versions of SIO are distributed by US Mail, electronically
     mail and from the SIO Distribution and Support BBS.  Users desiring to
     register electronically, may call the BBS and register on line (1-703-
     494-0098 or 199.248.240.2) and immediately download their registered
     version of SIO.  Use the ORDER command at the main BBS prompt.

     Registrations/Orders can also be placed by phone, mail, FAX, and
     email.  See the front cover of this manual for the phone numbers and
     addresses.  Also see ORDER.TXT for and order form that may be used.

     Support
     Extensive testing has been done to insure that this product works on
     the widest possible range of OS/2 V2 (and up) systems.  In most cases,
     problems can be resolved by reading this manual carefully.

     Support is provided in section 4 of the OS/2 Vendor Forum on
     CompuServe (GO OS2BVEN).  Section 4 of the OS2BVEN Forum is dedicated
     to the support of SIO.

     In addition, support is provided by BBS, Email and FAX.  Voice support
     would overwhelm the author and is not available.  If, after reading
     the manual carefully, you are unable to resolve a problem, you may
     submit a problem report to one of the following: 
                                      Email
                              CompuServe 71154,575
                             Internet ray@gwinn.com
                               FAX 1-703-494-0595
                       BBS 1-703-494-0098 or 199.248.240.2

     Users should note that Support does not always result in a correction
     of a problem.  In addition, the support provided is support of SIO,
     and not the applications that use SIO.  Questions and/or problems
     about applications programs (such as terminal or FAX programs) should
     be directed to the available support for the application.




                                                                          4


     Updates

     In general, updates/upgrades of SIO are free of charge for all
     releases of SIO with the same major version number.  However, there
     may be a handling charge if the user requires the upgrade to be mailed
     or emailed.

     Registered users of SIO can update to the latest version FREE of
     charge using the BBS and its UPDATE command.  Be sure to have your SIO
     serial number when you first log onto the BBS.  All variations (number
     of ports) of SIO are available for immediate download from the BBS by
     registered users.

     Users that have a registered copy of SIO can also use REREG.EXE to
     transfer the registration information to a new version of SIO.  Simply
     unzip the new SIO files into a temporary directory, change to that
     directory, execute REREG and answer the questions.  After doing the
     above, all of the files in the temporary directory will have been
     registered.  You must then copy all the SYS and EXE files from the
     temporary directory to their normal directory (overlaying the old
     registered version) or execute the SIO install program (INSTALL.EXE). 
     Then you must reboot.  You may also want to check your CONFIG.SYS for
     the path of the SIO/VSIO being loaded and make sure both the new ones
     are being loaded.

     If REREG will not transfer your registration information from a
     previous version of SIO to the new version, then an upgrade must be
     ordered on disk or obtained from the support BBS.




                                                                          5

                                 GETTING STARTED

     Installing SIO/VSIO

     SIO is distributed as a ZIP file.  To extract the individual files
     from the distribution file you need the program PKUNZIP or an
     equivalent.  PKUNZIP is a product of PKWARE and can be downloaded from
     almost any bulletin board system (BBS).  You probably already have
     PKUNZIP and know how to use it, otherwise I doubt that you would be
     reading this.  When PKUNZIP is used to extract the various files, -AV
     should appear after each file name as it is extracted.  In addition,
     the message:

          Authentic files Verified!

     should appear after the extraction process.  If this message does not
     appear, or appears with a name other than Raymond L. Gwinn, the file
     is not an original SIO distribution file.

     The only file that the basic user actually needs is SIO.SYS.  Virtual
     DOS machine (VDM) users will also want VSIO.SYS.  Copy one or both of
     these files to a convenient directory or subdirectory on your system. 
     An installation program (INSTALL.EXE) is provided to install the SIO
     files and modify your CONFIG.SYS

     Quick Start

     Create a temporary directory, change into that directory and unzip the
     SIO distribution zip there.  Type INSTALL followed by the enter key. 
     For a basic setup, that is all that is needed.

     If you choose to install SIO manually, the following should be done.

     BE SURE THAT ANY SERIAL MOUSE DRIVER APPEARS IN THE CONFIG.SYS BEFORE
     SIO.SYS

     If you are going to use standard communications ports, either COM1 or
     COM2 on an ISA bus (AT or clone), or COM1 through COM4 on a PS/2, then
     add the following line to your CONFIG.SYS file:

          DEVICE=SIO.SYS
          DEVICE=VSIO.SYS

     Be sure to REMark out the COM.SYS and VCOM.SYS device drivers if they
     exist in your CONFIG.SYS.

     With the above statements you will be able to use standard COM1 and/or
     COM2 (if they exist) on any PC system known to the author.

     If your setup is more complex, you must read on.




                                                                          6

                              COMMAND LINE OPTIONS

     The command line options are included in the command line that loads
     SIO in the CONFIG.SYS file.  VSIO has no command line options. 
     Command line options are usually grouped by port within parenthesis.

     If you use only COM1 and/or COM2, at the standard IRQ and port
     addresses, you will not need any command line options.  However, up to
     four serial communications ports, COM1 thru COM4, can be specified at
     any base port address and any IRQ.  On PS/2 systems and some ISA
     cards, SIO/VSIO supports multiple communications devices sharing the
     same IRQ.

     The basic command line syntax is as follows:

          DEVICE=SIO.SYS (Cn, An, In, Ig, Fc) [(Cn, An, In, Ig, Fc)]

     Where
          "Cn" is the comm port number (1 thru 4) or the string COM1 thru
          COMn.  The port number may preceeded by an asterisk "*" to
          indicate that the port may be used as a PCMCIA comm port (eg *1
          or *COM1).  Note that it is normal for SIO to display a warning
          about not finding anything at PCMCIA ports.

          "An" is a hexadecimal number that defines the base hardware I/O
          port address for the communications port.  If this field is left
          blank, the default I/O port address is used for the comm port. 
          Note that default I/O addresses exist only for COM1 through COM4
          on AT type systems and for COM1 through COM8 on PS/2 systems.

          "In" is an IRQ number (0 thru 15) or the string IRQ0 thru IRQ15
          or the string NONE.  It is best if one leaves this field blank
          and allows SIO to determine the IRQ, see AUTOMATIC IRQ ASSIGNMENT
          below.  The IRQ choice of NONE is provided for cards that can
          work either with or without an IRQ like the Hayes ESP.

          "Ig" is an ignored parameter.  If exists for compatibility with
          COM.SYS.

          "Fc" is the Forced 16550A chip parameter.  If an F is placed in
          this position, a 16550A UART chip type is forced regardless of
          the automatically detected chip type.




                                                                          7


     For a PC with COM1 and COM2 of standard configuration, the following
     command line will load SIO correctly:

          DEVICE=SIO.SYS (1, 3F8, 4) (2, 2f8, 3)

     A more readable, but identical, command line is:

          DEVICE=SIO.SYS (COM1,3F8,IRQ4) (COM2,2F8,IRQ3)

     Forcing a 16550A on COM1 would be as follows:

          DEVICE=SIO.SYS (COM1,3F8,IRQ4,,F) (COM2,2F8,IRQ3)

     In a similar manner, up to sixteen serial communications ports (four
     in the Shareware version) can be defined and supported by SIO and
     VSIO.




                                                                          8

                         Development and Debugging Tools

     The Poor Man's Line Monitor (PMLM.EXE)

     PMLM is basically of interest to developers of comm applications and
     those providing technical support for those applications.  This SIO
     utility is released largely (in self defense) in the hope that some
     users can diagnose their own problems.  PMLM's feature of saving trace
     information to disk will only work with registered and beta versions
     of SIO.

     PMLM provides basic line monitoring for OS/2, DOS and Windows comm
     programs.  All characters sent or received by application programs are
     displayed in the upper portion of the screen.  Receive characters are
     displayed as "white on blue" and transmitted characters are displayed
     "yellow on violet".  Line signals, such as CTS are displayed as "dim
     white on red" when turned off and "bright white on red" when turned
     on.  In addition, a signal's transition to OFF is displayed in lower
     case and a signal's transition to ON is displayed in upper case.

     Status information is displayed in the lower part of the screen.  A
     bright white display means the signal is on, a dim white indicates
     that the signal is off.  In addition, when bright,  Rxoff and Txoff
     indicate the SIO has sent (Txoff) or received (Rxoff) an Xoff, and an
     Xon is pending.

     When a DOS or Windows session uses a comm port, an additional line of
     signal status appears.  This status line shows the state of the
     virtual UART's signals.  Only the signals which MAY be different from
     the real UART's signals are shown.

     "Rx Chars" and "Tx Chars" reflects the number of characters in SIO's
     receive and transmit buffers respectively.

     The last line on the screen shows the keys (from the keyboard) that
     PMLM will recognize.  The bright character shows the key to hit for
     the associated function.  The font keys will not work in a windowed
     OS/2 session.

     PMLM's command line requires one parameter, the comm port number, and
     optionally accepts an additional parameter giving a save trace file
     name.  For example, PMLM 1 COM1INFO.TRC will monitor COM1 and save ALL
     of the communications traffic in the file COM1INFO.TRC.  The trace
     files created by PMLM contain exactly the same information that is
     displayed by PMLM, video attributes and all.




                                                                          9


     VIEWPMLM.EXE may be used to view trace files created by PMLM. 
     VIEWPMLM.EXE requires one parameter, the trace file name.  The user
     can use the keys UP, DOWN, PAGEUP, PAGEDOWN, HOME, and END to navigate
     the saved trace file.  Registered SIO users may send VIEWPMLM.EXE
     (along with saved trace files) to anyone for technical support
     purposes.

     VIEWPMLM can be used in native DOS, in DOS sessions under OS/2, and in
     OS/2 sessions.  This means that even those developers and support
     people need not have OS/2 to view the captured communications data
     created by PMLM.

     SIO's Utility (SU.EXE)

     This utility program has several useful commands.  You can obtain a
     list of the available commands by typing SU at any command line prompt
     without any parameters.  One very useful command is SU IRQS.  This
     command will show IRQs that are currently free for use.  Commands are
     provided allowing user control (missing from MODE) are available. 
     Status commands provide a wealth of diagnostic information.




                                                                         10

                           Intelligent Cards Supported


     Hayes ESP

     The original ESP (ESP V1) is not supported.  The SIO command line must
     contain the ESP's enhanced I/O port address.  For bit rates exceeding
     180000bps the IRQ MUST be specified for the master port. For lower
     data rates NONE may be specified for the IRQ.  SIO does not search for
     the ESP ports as the Hayes drivers do under DOS/Windows.  This
     searching can (will) break things under OS/2.  The SIO command line
     for an ESP at I/O port 180h using IRQ14 would be as follows:

     DEVICE=path\SIO.SYS (COM1,180,IRQ14)

     If you would like the above reflected to DOS sessions as a standard
     COM1, then use the following command line:

     DEVICE=path\SIO.SYS (COM1,180:3F8,IRQ14:IRQ4)

     Note that the numbers after the colons ":" are the address and IRQ of
     where the port appears to DOS software running under OS/2.  
     Any IRQ specified for an ESP slave port is ignored.  For those that
     like to have a clean looking CONFIG.SYS, SIO will accept NONE as the
     IRQ specification of an ESP slave port.

     If you wish to use the ESP in Compatibility Mode, simply specify the
     base port address that the ESP's compatibility mode is configured for
     (ie 3F8 when configured for COM1).

     Telcor Tport

     The Telcor Tport is supported in both burst mode and 16450 emulation
     mode.  When in burst mode, the Tport's 16k FIFOs are enabled. 
     Additionally in burst mode, no IRQ is used by the Tport.  In burst
     mode, any IRQ specified for the Tport is ignored.  For those that like
     to have a clean looking CONFIG.SYS, SIO will accept NONE as the IRQ
     specification of a Tport.  An example command line defining a Tport
     card to be used in burst mode; and that is configured for COM1
     follows:

     DEVICE=path\SIO.SYS (COM1,Tport@3F8,NONE:IRQ4)

     The Tport's 16450 Emulation mode simply uses a normal SIO command
     line. eg:

     DEVICE=path\SIO.SYS (COM1,3F8,IRQ4:IRQ4)

     In both examples the "IRQ4" following the colon above, means that the
     virtual IRQs are to be sent to a VDM on IRQ4.




                                                                         11


                            AUTOMATIC IRQ ASSIGNMENT

     SIO will automatically locate the IRQ that a comm port is attached to. 
     The IRQ used by SIO for a given comm port is assigned in the following
     manner:

     1 - If an IRQ is specified in the SIO command line then that IRQ is
     used.  However, SIO will display a warning message if the IRQ seems to
     be other than specified.

     2 - If no IRQ is specified in the command line, and if SIO detected
     the IRQ then the detected IRQ is used.

     3 - If no IRQ is specified in the command, and if SIO could NOT detect
     an IRQ then the default IRQ for the comm port is used.  SIO will also
     display a warning message in this case.

     The following STYLE command line is recommended for all but the most
     unusual systems.  That is, specify only the port number for those
     above COM2 (to tell SIO to support those ports) and let SIO do the
     rest.

     DEVICE=SIO.SYS (COM3) (COM4)

     If you do not have a COM3 or COM4, or if the mouse is using the only
     comm port above COM2 then the following command line should be used.

     DEVICE=SIO.SYS




                                                                         12

                                  DOS SETTINGS

     VSIO gets its operational characteristics from DOS Settings.  Several
     basic DOS Settings are provided.  They specify the type of access (if
     any) that a DOS program is to have to a communication port that SIO
     controls.

     All of the DOS Settings default to what most users should use most of
     the time (which is ON).  Also, all of the DOS Settings are prefixed
     with SIO_.

     If any of the DOS settings are changed, then the DOS session must be
     restarted from the Work Place Shell for the changed setting to take
     affect.

     The provided DOS Settings and their meaning follow:

          "SIO_Allow_Access_COMn" (where n is 1 thru 4).  This DOS setting
          defaults to ON.  If this setting is turned OFF for any or all of
          the ports, the DOS program will not be allowed any access to that
          port(s).

          "SIO_Virtualize_COM_Ports"  This Dos setting defaults to ON and
          it applies to all communications ports used by the DOS session. 
          When ON, this DOS setting means VSIO is to act as an interface
          between the SIO and the DOS program.  When OFF, the DOS program
          is given direct access to the hardware ports of the UART(s).

          "SIO_Virtualize_16550A"  This DOS setting defaults to ON and it
          applies to all communications ports used by the DOS session. 
          When ON, VSIO will simulate a 16550A.  When OFF, VSIO will
          simulate a 16450.  Some DOS programs may not work when a 16550A
          is simulated.  Turning this setting off may allow the program to
          work (but slower).

          "SIO_Share_Access_With_OS/2"  This DOS setting defaults to ON and
          it applies to all communications ports used by the DOS session. 
          When ON, SIO will allow an OS/2 session to access a
          communications port which the DOS session first opened (and has
          not closed).  If set to OFF, then the DOS session will have
          exclusive use of the communications port(s) that it uses.

          This setting does not apply to a second DOS session attempting to
          access a communications port,  two different DOS sessions are
          never allowed to access the same port at the same time. 
          Additionally, this setting has no affect upon the access to a
          communications port which is first opened by an OS/2 session.




                                                                         13


          "SIO_Screen_Sync_Kludge" DOS setting.  This DOS setting defaults
          to off and it applies to all communications ports used by the DOS
          session.  Some DOS BBS programs (such as Wildcat) and many DOS
          Door programs attempt to synchronize the screen output with
          transmitted data.  This plays havoc with a multi tasking system
          like OS/2 and results in very slow transmitted data.  When this
          setting is on, an attempt is made to fake out these misbehaved
          programs and allow them to run at normal transmit speed.  This
          setting should not be turned on unless you experience VERY slow
          transmission from a DOS program.

     All of the DOS Settings that begin with "SIO_Mode"  allows one to
     construct a MODE command for a DOS session.  These settings apply to
     SIO proper, and not necessarily to the DOS program itself.  For
     example, if you set XON/XOFF handshake with the appropriate SIO_Mode
     setting, you are specifying that SIO is to implement the handshaking. 
     The DOS application itself will be unaware of this handshaking.  This
     can be very confusing, so think it through before you start changing
     the defaults.

     The "SIO_Mode" settings WILL NOT BE APPLIED IF THE COMM PORT IS
     ALREADY OPEN WHEN THE DOS SESSION FIRST ACCESSES THE COMM PORT.  This
     means that the "SIO_Mode" settings will NOT be asserted for spawned
     DOS comm programs.  That is, for spawned DOS comm programs, the mode
     of operation that is already in effect will continue to be in effect
     and the "SIO_Mode" settings are ignored.

          "SIO_Mode_DTR"  This setting has three options that specify how
          SIO and VSIO are to treat the DTR signal.  The there available
          option are:
                    No Change at OPEN or CLOSE.
                    Turn ON at OPEN, OFF at CLOSE.
                    HandShake Signal, as in DTR/DSR.

               If either of the first two settings is selected, then
               basically the DOS application has direct control over the
               DTR signal.  If the second option is selected, then DTR will
               be turned on by SIO when the DOS program first touches the
               comm port.

               If the third option is selected, then SIO will use DTR as a
               handshaking signal.  That is, DTR will be turned off if SIO
               can not accept any further receive data.  In addition, if
               the DOS application program turns off the Virtual DTR, VSIO
               will stop supplying the DOS application with receive data.




                                                                         14


          "SIO_Mode_IDSR"  This setting specifies how SIO is to react to
          received data and the DSR signal.  The two available options are:
                    Ignore DSR During Receive.
                    Required for Valid Receive Data.

               If the first option (the default) is selected, then SIO will
               ignore DSR and accept all received data.  If the second
               option is selected, then SIO will ignore received data when
               the DSR signal is off.  VSIO ignores this DOS setting.




                                                                         15


          "SIO_Mode_OCTS"  This setting specifies how SIO will react to the
          CTS signal when transmitting data.  The two available options
          are:
                    HandShake Signal, as in RTS/CTS.
                    Ignore CTS During Transmit.

               If the first option (the default) is selected, then SIO will
               not transmit data when the CTS signal is off.  If the second
               option is selected, then SIO will ignore CTS during
               transmit.  Note that this setting should be set to "Ignore"
               for 3 wire connections like the Seiko Smart Label Printer,
               and Laplink.  VSIO ignores this setting.

          "SIO_Mode_ODSR"  This setting specifies how SIO is to react to
          the DSR signal during transmit.  The two available options are:
                    Ignore DSR During Transmit.
                    HandShake Signal, as in DTR/DSR.

               If the first option (the default) is selected, then SIO will
               ignore DSR during transmit.  If the second option is
               selected, then SIO will not transmit data when the DSR
               signal is off.  VSIO ignores this setting.


          "SIO_Mode_RTS" This setting has three options that specify how
          SIO and VSIO are to treat the RTS signal.  The there available
          option are:
                    HandShake Signal, as in RTS/CTS.
                    No Change at OPEN or CLOSE.
                    Turn ON at OPEN, OFF at CLOSE.

               If either of the last two settings is selected, then
               basically the DOS application has direct control over the
               RTS signal.  If the last option is selected, then RTS will
               be turned on by SIO when the DOS program first touches the
               comm port.

               If the first option (the default) is selected, then SIO will
               use RTS as a handshaking signal.  That is, RTS will be
               turned off if SIO can not accept any further receive data. 
               In addition, if the DOS application program turns off the
               virtual RTS signal, VSIO will stop supplying the DOS
               application with receive data.




                                                                         16


          "SIO_Mode_XON/XOFF"  This setting specifies if (and how) SIO is
          to use XON/XOFF flow control.  The four options are:
                    No XON/XOFF flow control by SIO.
                    Received XON is flow control.
                    Sent XON is flow control.
                    Rcvd and Sent XON is flow control.

               The first option (the default) specifies that SIO is not to
               use XON/XOFF flow control at all.  The second option
               specifies that SIO is to treat received XON/XOFF as flow
               control, but that SIO must not send XON/XOFF as flow control
               characters.  The third option specifies that SIO may send
               XON/XOFF as flow control characters, but that received
               XON/XOFF characters are to be treated as normal data.  The
               fourth option turns on XON/XOFF flow control in both
               directions, meaning that all sent and received XON/XOFF
               characters are flow control.




                                                                         17


          "SIO_Mode_FIFO_Load_Count"  This setting specifies how many
          characters that SIO will load into a 16550A UART at one time. 
          The choices are 1 and 16 (16 is the default).  The only case
          known to the author where one would select a setting of 1, is
          when very fast reaction to flow control is needed.  One such case
          is the Seiko Smart Label Printer which uses XON/XOFF flow control
          and a 3 wire connection.  If one is using a 16550 with a load
          count of 16, then 16 additional characters may be sent after an
          XOFF is received.  This condition will overrun the Seiko Printer. 
          If the "Load Count" is set to 1, then SIO will transmit (at most)
          two additional characters following a received XOFF which allows
          the Seiko Printer to work.  A setting of 1 will cause additional
          system overhead due to additional transmit interrupts.




                                                                         18


                             Configuration Profiles

     I will attempt to provide the DOS Settings that one should try for DOS
     communications programs in this section.  The settings may not work on
     all systems.  I will add to this section as I receive information from
     users.  All DOS Settings that are not given should be at their
     defaults.

     Seiko Smart Label Printer.
          I tested the Seiko printer successfully using the following DOS
          settings for SIO:

          SIO_Mode_DTR                No Change at OPEN or CLOSE
          SIO_Mode_FIFO_Load_Count    1.
          SIO_Mode_IDSR               Ignore DSR During Receive
          SIO_Mode_OCTS               Ignore CTS During Transmit
          SIO_Mode_ODSR               Ignore DSR During Transmit
          SIO_Mode_RTS                No Change at OPEN or CLOSE
          SIO_Mode_XON/XOFF"          Received XON is flow control

     In addition, you should run the printer in its own separate Win-OS/2
     session.

     IBM's SLIP
          I have been told by many users that a MODE command is required
          for IBM's SLIP program to work correctly.  The recommended MODE
          command is as follows:

          MODE DTR=ON




                                                                         19

                    Differences between SIO/VSIO and COM/VCOM

     What follows is some of the differences between SIO/VSIO and COM/VCOM
     that are known to the author.

     1 -  COM.SYS will automatically seek out and support four comm
          ports, COM1 through COM4.  SIO.SYS will automatically seek
          out and support only COM1 and COM2.  If SIO.SYS is to
          support more than two comm ports, they must be defined in
          the command line that loads SIO.SYS.  For example,
          DEVICE=SIO.SYS (COM3) (COM4) will cause SIO.SYS to support
          four comm ports.

     2 -  In the absence of overrides in the command line, COM.SYS
          will seek out four comm ports in the sequence of I/O ports
          3F8h, 2F8h, 3E8h and 2E8h.  The first port found in this
          sequence is given the logical name COM1, the second is COM2
          etc.  This means that the comm port at 2F8h could become
          COM1.  In the opinion of the author, this confuses some
          users to frustration.

          With no command line overrides, SIO.SYS uses a fixed I/O
          port concept.  That is, COM1 is always at I/O port 3F8h,
          COM2 is always at 2F8h, etc.  Another way of looking at this
          is;  if no comm port exists at port 3F8h, then you do not
          have a COM1.  SIO.SYS will not move another (found) comm
          port into the logical COM1 slot.

     3 -  VSIO opens a comm port for a DOS session with sharing allowed. 
          VCOM uses an "exclusive use" open for DOS sessions.

     4 -  SIO.SYS always controls the FIFOs of the 16550 UART.  SIO.SYS
          will not allow an application program (OS2 or DOS) to disable the
          FIFOs of a real 16550.  The application may specify the transmit
          fifo load count.

     5 -  SIO.SYS will accept any number between 50 and 115200 (921600 if a
          Hayes ESP) as a valid baud rate.  For example, if an application
          program attempts to set a baud rate of 9990 bps, COM.SYS will
          reject it and SIO.SYS will accept it.

     6 -  SIO/VSIO execute faster than COM/VCOM.  This means that some
          applications, that are timing dependent, may not work under
          SIO/VSIO that do work under COM/VCOM.




                                                                         20


     7 -  SIO/VSIO provides more reliable active flow control for DOS
          sessions.  For example, if RTS/CTS handshaking is in use, VSIO
          processes the RTS settings by the DOS program while SIO
          completely controls the real RTS signal.  COM/VCOM simply passes
          the RTS signal directly to the hardware.

     8 -  COM.SYS will block an application until a write completes.  SIO
          will return to the application program immediately if all of the
          write data will fit into SIO's internal buffers.




                                                                         21


                             PROBLEMS AND SOLUTIONS

     1 -  Port already in use is displayed.

          This message is displayed when the comm port or the IRQ is in
          use.  If the comm port is not actually in use, the IRQ is most
          likely in use.

     2 -  SIO displays a warning message that the IRQ for a port appears to
          be wrong, but the port works.

          SIO probably detected more than one IRQ attached to the comm
          port.  This indicates a possible hardware problem with your
          system that you may want to have checked.

     3 - The modem will not initialize.

          Configure your comm program(s) to insert a delay between modem
          initialization characters as they are sent to the modem.

     4 - WinFax locks up during install.

          During the WinFax install, temporarily turn OFF the DOS setting
          SIO_Virtualize_COM_Ports.  Once installation is complete, the
          setting SIO_Virtualize_COM_Ports can be restored.

     5 - Telemate does not recognize VX00 as a FOSSIL.

          Set the baud rate in Telemate to less than 57600.

     6 -  Comm output is very slow from DOS.

          This is a problem common to many DOS BBS and Door programs.  They
          attempt to synchronize the local screen with the transmitted
          data.  That is, they send a character, wait until it is sent and
          then display the character on the local screen.  This does not
          cause a problem for the single tasking DOS environment.  However,
          this procedure causes at least two (probably more) context
          switches in the multi-tasking environment of OS2, which in turn
          brings the processor to its knees.  One possible solution is for
          the programmer to synchronize line by line instead of character
          by character.




                                                                         22



     7 -  Procomm stops receiving

          Procomm seems to have a bug in its implementation of RTS/CTS
          handshaking.  The problem shows up most often when Procomm is
          windowed.  Under certain conditions, Procomm will turn the
          virtual RTS OFF and does not turn it ON again.  This prevents
          VSIO from sending further data to Procomm if SIO_Mode_RTS is set
          for RTS/CTS handshake.  A solution to the problem that seems to
          work is to set SIO_Mode_RTS to other than RTS/CTS handshake. 
          Note that SIO_Mode_RTS should be set for RTS/CTS handshake under
          almost all other conditions.




                                                                         23


     9 - WinFax does not work well.

          a- Connect problems with recipient's fax station

          b- Cannot send more than one page of a multiple page fax

          c- Transmission fails between pages

          d- Transmitted pages are corrupted, missing parts, or cut off.

          Class 1 FAX modem.
                    The modem init strings set by WinFax 3.0 will work in
                    the single-layered comm world of DOS and Windows. 
                    However, these modem init strings will not work in the
                    multi-layered comm environment used by OS/2. 
                    Specifically, WinFax 3.0 sets the modem to use only
                    Xon/Xoff flow control.  Ideally, both Xon/Xoff and
                    Hardware handshaking needs to be set.  If only one
                    handshake can be set, set the modem to Hardware
                    handshake.  For USR FAX modems, use &H3, for many other
                    modems, the setting is &K3.  Additionally, for WinFax
                    3.04 and up, place the following in your WINFAX.INI
                    file:
                         HdwFlowControl=1

          Class 2 FAX modem.
                    It seems to the author that hardware handshake screws
                    up some (possibly all) class 2 FAX modems.  Therefore,
                    when using a class 2 modem, WinFax should be configured
                    to use XON/XOFF handshaking.  For WinFax 3.04 and up,
                    place the following in your WINFAX.INI file:
                         HdwFlowControl=0

                    The author feels that the inability to use hardware
                    handshake with class 2 FAX modems is a serious design
                    deficiency.

     10 - Serial Printer messes up on last page.

          Add the following command line to your CONFIG.SYS file:
               RUN=MODE COM1 TO=ON




                                                                         24

                               IRQ SHARING ON ISA

     Sharing the same IRQ for multiple communications ports on ISA systems
     is not for the weak of heart (or mind).  If you have problems with
     shared IRQs, DO NOT contact the author.  Contact the board or computer
     manufacturer for help.

     Some general rules are as follows:

     1 - Two different boards (plugged into different slots) can not share
     the same IRQ.  This is a hardware limitation of ISA systems and can
     not be corrected by software.  This means that you can not plug in two
     internal modems, set them for the same IRQ and expect them to work. 
     This does not apply to PS/2 systems.  The problem of multiple boards
     sharing the same IRQ was corrected in the PS/2's bus design.

     2 - SIO can not (will not) share an IRQ with other device drivers at
     the same time.  SIO releases IRQs that it is currently not using. 
     This is different form how COM.SYS works.  This difference may show up
     as an unexpected "port already in use" error that does not occur with
     COM.SYS.  I have received reports that the SDLC drivers try to
     concurrently share IRQs with the ASYNC driver.  SIO.SYS will not allow
     this while COM.SYS will.




                                                                         25

                  Appendix A, Hardware Port and IRQ Assignments

     I have obtained the following information from various sources. 
     Accuracy is not guaranteed.  In fact, nothing in this document is
     guaranteed.

     Addresses and IRQs for COM1 and COM2

          COM1 uses 03F8h and IRQ4
          COM2 uses 02F8h and IRQ3

     Defacto standard for COM3 and COM4 for PC, XT and AT

          COM3 uses 03E8h and IRQ4
          COM4 uses 02E8h and IRQ3

     Addresses and IRQ for COM3 through COM8 on the PS/2

          COM3 uses 3220h and IRQ3
          COM4 uses 3228h and IRQ3
          COM5 uses 4220h and IRQ3
          COM6 uses 4228h and IRQ3
          COM7 uses 5220h and IRQ3
          COM8 uses 5228h and IRQ3

     All PCs (known to the author) prior to the PS/2 and EISA only use 10
     bits to address hardware I/0 ports.  Systems prior to the PS/2 and
     EISA can not address the standard PS/2 addresses for COM3 through
     COM8.  If an AT or below attempts to address COM3 through COM8 using
     the PS/2 addresses, only the low 10 bits of the address are used. 
     That is, the high digit of the hexadecimal address will be ignored. 
     This means that any reference to COM3 through COM8 will actually
     address ports 220h through 22Fh on older PCs.

     One should avoid expansion boards that use ports 220h through 22Fh
     unless the expansion board is a serial I/O board. 

     SIO will (attempt to) determine the hardware architecture (ISA/EISA
     and PS/2) that it is being executed on and use the appropriate
     hardware port addresses for COM1 thru COM4 as defaults.




                                                                         26

                              Appendix B, SIO Chips


     The following is a collection of comments developed from hearsay,
     random documents, experience, and technical specifications. So, take
     it with a grain of salt.  Order information from the various
     manufactures if you want accurate information.

     Very good reference books are available from National Semiconductor
     Corporation.  They cover most of the SIO devices (also called UARTs)
     that you will find in many PCs and clones.  I am not sure that books
     can be ordered directly from National semiconductor. They may require
     that you get it from a distributor.  In any case, the address on the
     back of the one manual is:

          National Semiconductor Corporation
          2900 Semiconductor Drive
          P.O. Box 58090
          Santa Clara, CA 95052-8090

          Tel:(408)721-5000
          TWX:(910)339-9240

     8250

     As best that I know, the 8250 was the first SIO chip (integrated
     circuit) that was used by the IBM PC and many clones.  In my opinion,
     it was a poor choice on the part of IBM.  I feel many superior
     devices, at comparable prices, were readily available.  At that time,
     I feel the 8251A or the 8530 would have been better choices.  But,
     they used the 8250 and therefore we must use it.

     From a hardware standpoint the 8250 is a relatively slow device.  It
     is advisable that programmers not perform successive inputs or outputs
     to this device.  It seems that software programs can load the various
     registers of the 8250 faster than it can process the information.  The
     8250 had a total of 7 registers.  The specifications state that 56kb
     is the maximum baud rate.

     8250A

     I believe the 8250A is the 8250 with some bug fixes.  I have no idea
     what the bugs may have been.  A quick glance at the specifications
     shows the speed of the 8250 and 8250A to be much the same.  The 8250A
     added an 8th register.  This additional register enables software to
     detect if an 8250 is installed.  The specifications state that 56kb is
     the maximum baud rate.




     16450

     The 16450 seems to be a speeded up version of the 8250A.  There is no
     direct way (that I know of) for software to detect the difference




                                                                         27

     between an 8250A and a 16450.  I believe the 16450 was developed to
     eliminate the need for software to insert delays between successive
     accesses to the device.  The specifications indicate the 16450 is a
     much faster device than its predecessors.  The additional speed is
     only the speed at which the processor can access the device.  The
     maximum baud rate for the 16450 is still stated at 56kb.  However, I
     have been told by some people that they have run the 16450
     successfully at much higher speeds. I do not believe there was ever a
     16450A.

     16C451

     The 16C451 is a CMOS version of the 16450.  CMOS is a term for the
     material and manufacturing process used to make the part.  CMOS
     typically uses less power than other technologies.  If you are not
     designing hardware, you should view the 16C451 as a 16450.

     16550 (Non A)

     It is hard to find a 16550 (Non A).  I was told by National
     Semiconductor that they did everything they could to get all 16550s
     back.  SIO will detect a 16550 and tell you if you have one.  I am
     told that the 16550 was installed in early PS/2 systems.

     The 16550 was the first shot at a FIFOed version of the 8250 family
     from National semiconductor.  However, I was told by National
     Semiconductor that the FIFOs of the 16550 are not reliable and they
     should not be enabled.  SIO will treat a 16550 like a 16450.  In this
     mode, they are reliable.  National Semiconductor would not provide me
     with a specification for the 16550.  However, I suspect its maximum
     baud rate is the same as the 16550A which is 256kb.

     16550A, 16550AF and 16550AFN

     In the manuals that I have, National Semiconductor does not explain
     the differences between the 16550A and the 16550AF.  I suspect the AF
     part may have a few bug fixes.  I believe the N in AFN describes
     packaging, ceramic versus plastic, DIP versus surface mount etc.

     In the opinion of the author, there is no substitute for the 16550A
     (and its successors) in the 8250 type series.  The 16550A is
     compatible with most software written for the entire family of 8250
     type devices.  Programs that are 16550A aware can provide much
     improved performance over previous devices.


     The maximum baud rate for the 16550A is specified at 256kb.  However,
     due to the hardware design of the PC et al, 115kb is the maximum baud
     rate that can be programmed by software.

     The 16550A can be plugged into the same socket that contains an 8250,
     8250A or 16450.  If your SIO expansion board has the SIO chips in
     sockets, you can upgrade to the 16550A by simply removing the old
     chips and replacing them with 16550As.




                                                                         28

     The key to the performance increase of the 16550A is its FIFOs.  It
     has 16 byte FIFOs for both transmit and receive data.

     16550s Made by Western Digital

     I have been told, but I have not verified for myself, that 16550s made
     by Western Digital have a problem with their FIFOs when working at
     2400 baud or below.

     16C551

     The 16C551 is a CMOS version of the 16550AF.  See the above
     description of the 16C451 for a discussion of CMOS.  Do not feel you
     need to upgrade from a 16550A or AF to a 16C551.  There is no gain
     from an existing users point of view.

     16C552

     The 16C552 is two 16C551s on a single chip.

     16C554

     The 16C554 is four 16C551s on a single chip.

     82510

     I believe Intel is the only company that manufactures the 82510.  The
     82510 is feature rich with several modes of operation.  Its default
     mode is to operate as a 16450.  The 82510 has a 4 byte FIFO for both
     transmit and receive data.  A 4 byte FIFO is sufficient to provide
     significant performance over a basic 16450.

     The 82510 is small in size.  Therefore, it is found in many lap tops.

     The 82510 is somewhat of a sleeper.  I believe it would be much more
     widely used if Intel had promoted it more.  However, given a choice
     between the 82510 and the 16550A, I would select the 16550A.




                                                                         29


     16650

     The 16650 by Startech seems a good logical step in the evolution of
     the 8250 type UARTs.  One of the many flavors of the 16650 is a
     package that is pin compatible with the 40 pin (DIP) 16550s.  This
     means that the 16650 can be placed into the same socket as any 16550,
     8250, etc.

     The 16650 has enhanced the FIFOs to 32 bytes, added on chip flow
     control ability, and increases the maximum bit rate to 460800.  The on
     chip flow control is a really nice feature.  On chip flow control
     practically eliminates the possibility of missed receive characters. 
     On chip flow control also means that some devices that require
     immediate attention when it sends Xoff, like the Seiko Label Printer,
     will work much better in environments like OS/2 and Windows.

     The 32 byte FIFOs of the 16650 is an improvement over the 16550, but
     is still a disappointment.  I feel that 1k, or larger, FIFOs would
     have been a much better choice.  When I quizzed Startech about this,
     they replied that the 32 byte FIFOs were chosen to keep the cost down. 
     They added that if the 16650 is successful, they plan a 16750 with
     larger FIFOs.

     The 16650 powers up in a 16550 compatible mode, meaning most software
     written for the 16550 should work.  I have discovered a serious
     incompatibility in the current (Oct 1994) versions of the 16650.  All
     previous UARTS in the 8250 family will issue only a single transmit
     interrupt if no additional data is sent to the UART.  The 16650 on the
     other hand, will issue continuous transmit interrupts making it
     necessary to mask the transmit interrupt.  I quizzed Startech about
     this and was told that a new revision of the chip would be available
     within a few months that would correct this incompatibility.




                                                                         30


     ComBic

     The ComBic is a very impressive UART used on the Hayes ESP card and
     some others.  The ComBic is basically a 16550 UART with on chip flow
     control and 1k FIFOs and a maximum bit rate of 921600.   Like the
     16650, on chip flow control practically eliminates the possibility of
     missed receive characters.  On chip flow control also means that some
     devices that require immediate attention when it sends Xoff, like the
     Seiko Label Printer, will work much better in environments like OS/2
     and Windows.

     The ComBic has two modes of operation, compatibility mode and enhanced
     mode.  In compatibility mode, the UART acts as a 16550.  However, when
     in compatibility mode, the 1k FIFOs and on chip flow control can still
     be used.  In enhanced mode, software gains the ability to look into
     the FIFOs and determine the exact number of bytes loaded.  This
     feature enables software the use block input and output to the ComBic
     which greatly reduces processor overhead.




                                                                         31

                     Appendix C, Multi-Port Serial I/0 Cards

     I have received many requests for information about multi-port serial
     I/O card.  I will describe the boards that I know about (or have heard
     about) here.  I will add to the list as I receive precise information
     from manufactures, users, or I develop it myself.

     Please do not contact me for support on the following boards, contact
     the manufacturer.  The following tells of my experiences with the
     boards and does not imply support.  Your experiences with a given
     board may be different.

     STB 4COM  (ISA bus)

     I am very impressed with the STB 4COM card, they have almost got it. 
     Yes, its the same company that makes the VGA cards.  The 4COM card
     uses a 16554 which is the equivalent of four 16550A.  Comm ports can
     use IRQs 2/9, 3, 4, 5, 10, 11, 12, and 15.  Any or all ports can share
     IRQs, and they have done this right.  I tested SIO with all four ports
     of the 4COM on IRQ12 and they worked correctly.  The user can select
     any of the following I/O port address for a comm port: 3F8, 2F8, 3E8,
     2E8, 1A8, 1E8, 1F8, 2A8.

     The 4COM card is priced at $110 and I ordered mine from Prerapture
     Solutions which can be reached by telephone at 1-919-286-1502 for
     information and foreign callers.  In the US orders can be placed by
     calling 1-800-735-5266.  Their mailing address is:
          Prerapture Solutions
          1806 Albany St.
          Durham NC 27705-3135

     Connect Tech Dflex-8

     This is one of the most configure able communications cards that I
     have ever seen.  It has on board simms to configure the electrical
     characteristics (RS232, RS442 etc).  The board that I tested was
     configured for RS232 and has 8 Startech 16550 on it.  All 8 ports can
     be jumpered to the same IRQ and the IRQ sharing seems to work well
     with SIO and I detected no performance problems.

     I have no pricing information, the Dflex was supplied to me at no
     charge.  Connect Tech can be reached at 519-836-1291.  Their mailing
     address is:

     Connect Tech Inc.
     727 Speedvale Ave. West
     Guelph, Ontario, Canada
     N1K 1E6




                                                                         32


     Gtek BBS550 (ISA bus)

     The Gtek BBS550 is a communications card with the equivalent of 8
     16550s (in reality two 16554s) UARTs.  Where were these cards 5 years
     ago!  Like the STB 4COM, I am very impressed with the BBS550.  It has
     a wide range of selectable I/O port address, some in the 16 bit range
     (above 3FFh) which can be very useful.  I tested the board with all 8
     ports installed using IRQ3 (although I never had more than 3 ports
     active at the same time).  The board performed well using shared IRQs.

     The BBS550 has 8 RJ-45 connectors (10 pin), 6 of which comes directly
     off the back of the card.  The other two RJ-45 connectors are internal
     and special cables with grommets are supplier for these 2 ports.  The
     cables supplied with the BBS550 expands the RJ-45 out to standard DB-
     25 connectors.

     Gtek is located in St. Louis Mississippi.  Their phone number is 800-
     282-4835 or 601-467-8048.

     Neotech Quad Serial (MCA bus)

     Well, I just got my first PS/2 system (for testing of SIO) and I am
     using the NeoTech Quad Serial card in that system.  What can I say, it
     works beautifully and interrupt sharing has never been a problem on
     MCA systems.  This card (as shipped) came with four individual 16450
     chips installed, but they were in sockets so I installed 16550 UARTs
     before I installed the card.  The card has one large connector on the
     back of the card and the supplied cable expands that to 4 standard DB-
     25 connectors.  Those of you needing a good 4 port card for an MCA
     system contact:

          Neotech Inc
          30295 Solon Industrial Pkwy.
          Solon, Ohio 44139

          Voice     (216) 248-4114
          FAX       (216) 248-5701




                                                                         33

                                      INDEX

     16450 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
     16550 (Non A) . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
     16550A  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
     16550AF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
     16550AFN  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
     16550s Made by Western Digital  . . . . . . . . . . . . . . . . . . 28
     16650 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
     16C451  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
     16C551  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
     16C552  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
     16C554  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
     8250  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
     8250A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
     82510 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
     Addresses and IRQ for COM3 through COM8 on the PS/2 . . . . . . . . 25
     Addresses and IRQs for COM1 and COM2  . . . . . . . . . . . . . . . 25
     Allow_Access_COMn . . . . . . . . . . . . . . . . . . . . . . . . . 12
     Appendix A, Hardware Notes  . . . . . . . . . . . . . . . . . . . . 25
     Appendix B, SIO Chips . . . . . . . . . . . . . . . . . . . . . . . 26
     Appendix C, Multi-Port Serial I/0 Cards . . . . . . . . . . . . . . 31
     AUTOMATIC IRQ ASSIGNMENT  . . . . . . . . . . . . . . . . . . . . . 11
     BBS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  3
     ComBic  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
     COMn already in use . . . . . . . . . . . . . . . . . . . . . . . . 21
     CompuServe  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  3
     CONFIG.SYS  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  5
     Connect Tech Dflex-8  . . . . . . . . . . . . . . . . . . . . . . . 31
     Defacto standard for COM3 and COM4  . . . . . . . . . . . . . . . . 25
     Development and Debugging Tools . . . . . . . . . . . . . . . . . .  8
     Differences between SIO/VSIO and COM/VCOM . . . . . . . . . . . . . 19
     Distribution  . . . . . . . . . . . . . . . . . . . . . . . . . . .  3
     DOS SETTINGS  . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     Email . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  3
     ESP in Compatibility Mode . . . . . . . . . . . . . . . . . . . . . 10
     Exclusive use . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     FAX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  3
     FAX Modems
          Class 1 FAX modem  . . . . . . . . . . . . . . . . . . . . . . 23
          Class 2 FAX modem  . . . . . . . . . . . . . . . . . . . . . . 23
     FaxWorks  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
     FIFO  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27, 28
     FMD.SYS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
     GETTING STARTED . . . . . . . . . . . . . . . . . . . . . . . . . .  5
     Gtek BBS550 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
     Hayes ESP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     Installing SIO/VSIO . . . . . . . . . . . . . . . . . . . . . . . .  5
     Intellegent Cards Supported . . . . . . . . . . . . . . . . . . . . 10
     IRQ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  6, 11
     IRQ SHARING ON ISA  . . . . . . . . . . . . . . . . . . . . . . . . 24
     ISA buss  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
     MCA buss  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
     National Semiconductor Corporation  . . . . . . . . . . . . . . . . 26
     Neotech Quad Serial . . . . . . . . . . . . . . . . . . . . . . . . 32




                                                                         34

     Ordering  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  3
     OS2BVEN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  3
     PCMCIA  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     PDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  2
     Physical Device Driver  . . . . . . . . . . . . . . . . . . . . . .  2
     PKUNZIP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  5
          Authentic files  . . . . . . . . . . . . . . . . . . . . . . .  5
     PMLM.EXE  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  8
     PROBLEMS AND SOLUTIONS  . . . . . . . . . . . . . . . . . . . . . . 21
     Quick Start . . . . . . . . . . . . . . . . . . . . . . . . . . . .  5
     RTS/CTS handshaking . . . . . . . . . . . . . . . . . . . . . . . .  2
     Seiko Smart Label Printer . . . . . . . . . . . . . . . . . 15, 17, 18
     Serial Printer  . . . . . . . . . . . . . . . . . . . . . . . . . . 23
     SIO Chips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
     SIO Technical Reference Manual  . . . . . . . . . . . . . . . . . .  i
     SIO's Utility (SU.EXE)  . . . . . . . . . . . . . . . . . . . . . .  9
     SIO_Mode_DTR  . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     SIO_Mode_FIFO_Load_Count  . . . . . . . . . . . . . . . . . . . . . 17
     SIO_Mode_IDSR . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
     SIO_Mode_OCTS . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
     SIO_Mode_ODSR . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
     SIO_Mode_RTS  . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
     SIO_Mode_XON/XOFF . . . . . . . . . . . . . . . . . . . . . . . . . 16
     SIO_Screen_Sync_Kludge  . . . . . . . . . . . . . . . . . . . . . . 13
     SIO_Share_Access_With_OS/2  . . . . . . . . . . . . . . . . . . . . 12
     SLIP  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
     STB 4COM  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
     Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  3
     Telcor Tport  . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     UART  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
     Updates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  4
     VDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  2
     VIEWPMLM.EXE  . . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     Virtual Device Driver . . . . . . . . . . . . . . . . . . . . . . .  2
     Virtualize_16550A_For_COM . . . . . . . . . . . . . . . . . . . . . 12
     Virtualize_COM_Ports  . . . . . . . . . . . . . . . . . . . . . . . 12
     WHAT IS SIO . . . . . . . . . . . . . . . . . . . . . . . . . . . .  1
     WHAT IS VSIO  . . . . . . . . . . . . . . . . . . . . . . . . . . .  2
     WinFax  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21, 23
