



                               Revision History


      The following changes/additions were made in internal build
      0.113.

           The initialization procedure for enabling the FIFOs of the
           16550 was changed as per directions from StarTech.  The
           StarTech 16550 is used in many Practical Peripherals modems. 
           This change may correct overrun and hanging problems for
           other users.  User reports indicate that the FIFOs
           initialization problem may go beyond the StarTech 16550 and
           thus, solve problems for users of other 16550s.

      The following changes/additions were made in internal build
      0.114.

           Additions to force enabling of comm ports for VMBs under
           2.1GA.

           Version number was changed to 1.01

      The following changes/additions were made in internal build
      0.115.

           The Interrupt Service Routine (ISR) was improved to insure
           that all pending interrupts of all ports sharing the same
           IRQ are serviced.

      The following changes/additions were made in internal build
      0.116.

           Additional changes to decrease the processing time of the
           Interrupt Service Routine.

      The following changes/additions were made in internal build
      0.117.

           Additional information added to the boot time banner.

           Changed the version number to 1.02.

      The following changes/additions were made in internal build
      0.118.

           Corrected erroneous sending of XON when receive flow control
           was enabled.

           Added code to clear the UART's FIFOs during initial file
           open.




      The following changes/additions were made in internal build
      0.119.

           Corrected a problem with hardware flow control for DOS
           processes.  This problem showed up most often in windowed
           DOS programs.

           Removed code specific to the March, 1993 beta of OS2.

           Added support for installable and removable communications
           devices, eg PCMCIA.

           Some users of VX00 will see improved performance from FOSSIL
           aware DOS programs.

      The following changes/additions were made in internal build
      0.120.

           Code added to allow I/O port mapping to DOS sessions.

      The following changes/additions were made in internal build
      0.121. 7/28/93 14:00pm

           Corrected a problem that would cause the system to hang if
           an SIO command line error was detected.

           Additional code added for "hot plugging" of PCMCIA comm
           ports.  Users of PCMCIA comm devices should not remove those
           devices while a comm program active.  Many comm application
           programs can not cope with the modem being removed.  Your
           system may lock up if you remove a modem while a comm
           application program is active.

           Changed the way virtual CTS is handled.  In previous
           versions, the virtual CTS was always on.  Under appropriate
           conditions, the virtual CTS will now be turned off.

      The following changes/additions were made in internal build
      0.122. 8/14/93 14:20

           Corrected a problem in the internal (to SIO) shared
           interrupt chain.  This problem would cause the system to
           lock up when the third device checked in on the same IRQ.

           Added command line options for PCMCIA.



      The following changes/additions were made in internal build
      0.123. 8/18/93 19:05

           Added code to wake sleeping receive threads when a Flush
           Input command is received.  This additional code allows HA/5
           Version 3.1 to work with SIO.

           Changed the version number to 1.10 and released it for
           downloading.

      The following changes/additions were made in internal build
      0.124. 8/28/93 14:50

           Corrected a serious error in SIO.  This problem could show
           up in almost any way.  The most common symptom is/was trap
           000e and inordinate processor overhead when comm is active.

      0.125. 9/09/93 08:15

           Changed version number to 1.11

           Corrected problem associated with generating a virtual
           transmit interrupt.  This problem was introduced with the
           released version 1.10.  It broke PCBoard, among others.

           Added DTR/DSR handshaking.  It seems that several printers
           requires this type of handshaking.  This addition
           necessitated the addition of the DOS Setting
           SIO_Virtual_DTR_is_HS.  This new DOS setting is the first
           SIO setting that should normally be off.  When a DOS or
           Windows session is using DTR/DSR handshaking, this setting
           should be turned on.  The HP laser printers are the only
           devices that I know of (or ever heard of) that use DTR/DSR
           hardware handshaking.  All modems that I know of use RTS/CTS
           hardware handshaking.

      0.126 09/22/93

           Corrected problems that were introduced when the PCMCIA code
           was added and released in V1.10.  These problems caused
           several DOS and Windows programs to work poorly or not at
           all.  These problems also caused some DOS and Windows comm
           programs to use inordinate amounts of processor time.

           Changed the version 1.13.

           Corrected a problem in the FOSSIL implementation of VX00. 
           Some FOSSIL aware programs that previously did not work
           under VX00 may now work.




      0.127 09/30/93 17:20

           Changed version number to 1.15 and released.

           Added DOS settings to allow for individual mode settings for
           each DOS session.  The DOS Settings SIO_Virtual_RTS_is_HS
           and SIO_Virtual_DTR_is_HS have been removed.  Their function
           is more completely covered in the new DOS Settings.

           Optimized code to eliminate unnecessary virtual transmit
           interrupts.  This change should cut down the amount of
           overhead placed upon the system by DOS and Windows comm
           programs.

           Changed the way the DCB is processed so that CTS may be
           ignored (if instructed by the DCB) even when RTS is a
           handshake signal.

           Previously, SIO would force RTS/CTS handshaking if the baud
           rate is locked in the command line.  The forcing of RTS/CTS
           handshaking has been removed.

           A flow control problem that showed up on some systems has
           been corrected.  The flow control problem most often showed
           up at transmission simply stopping.  This problem was
           introduced when the DTR/DSR handshaking was added.

           Added the "SIO_Share_Access_With_OS/2" DOS setting.

           Changed version number to 1.20.

      0.129 10/30/93 12:30

           Added code to support SU's VIRT command and additional
           information from the ABOUT command.  It should be noted that
           SU's MODE command will show the mode of an active comm
           program, and that SU's output can be redirected to a disk
           file.  For example SU 1 MODE > XXXX will direct SU's output
           to a file named XXXX.  When submitting a problem report, one
           should use SU's mode command while the problem program is
           active and include the information in the problem report.

           A new DOS setting has been added, SIO_Idle_Sensitivity. 
           This setting parallels the IDLE_SENSITIVITY setting of OS/2
           to some degree, but the new SIO setting applies only to DOS
           comm and not to the system in general.  Lowering the value
           of this setting will increase the processor time made
           available to other processes.  However, setting the value
           too low will screw up the operation of some DOS comm
           programs.  Setting the value to 100 (the default) will cause
           SIO to use its previous methods of releasing processor time
           (which are not very good).




           Added code to support SU's new CLOSE command.  The CLOSE
           command attempts to force a DOS session to release a comm
           port.

           The method in which the SIO_Mode setting are implemented has
           been changed.  These settings specify only the initial mode
           settings to use for a DOS session.  Changes made to the mode
           (via a MODE or other command) within the DOS session are no
           longer lost.  The SIO_Mode settings isolate the DOS VDM's
           mode from that of OS/2 sessions in all but one case.  The
           one case is when the port is already opened when DOS first
           accesses it.  In this one case, the SIO_Mode settings are
           not applied.  Except for this one case, one should view OS/2
           as having its mode settings and DOS sessions as having an
           independent group of mode settings. 

           Corrected a problem in the SIO_Mode_Xon/Xoff implementation. 
           If this setting enabled the sending of Xon/Xoff, then under
           some conditions, an Xon would not be sent following the
           sending of an Xoff.  This problem only applied to DOS
           programs using the above DOS Setting.

      0.130 11/16/93 12:00

           Code added to SIO.SYS to support PMLM.EXE.  PMLM.EXE is a
           line monitoring program similar to X00's BOB.EXE.

           Corrected a problem that would cause erroneous "Port in use"
           errors from a DOS session if sharing with OS2 sessions was
           disabled.

           Added the "SIO_Screen_Sync_Kludge" DOS setting.  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.

           Corrected a problem in SIO with sending break.  At high bit
           rates, SIO would lock the entire system if a break was sent. 
           That problem has been corrected.

           Added a warning message at load time about possible IRQ
           conflicts with other device drivers.

           Added code to support SU's IRQ usage report.

           Corrected a problem that caused an opened comm port to
           lockup when the SU IRQS command is used.




           Added additional FOSSIL baud rates to function 1Eh.  See
           X00REF.DOC in X00153A.ZIP for additional information.

           Corrected a problem in SU with enable/disable commands. 
           Enable now works following a disable.

           Added the Lock command to SU, allowing a locked baud rate to
           be reset or unlocked.

           VSIO.SYS will now refuse to load if COM.SYS has been loaded.

      0.131 12/22/93 18:00

           Changed version to 1.24 and released.

           MERRY CHRISTMAS!!!!

