Play/D command line options

-a     Indicates the amount of memory (in K bytes; 1K = 1024 bytes)
       to allocate for MIDI file storage.  The default is -a24 (24K bytes).


-m     Selects the operating mode: 1, 2, or 3.  The default is -m1.

       Mode 1:      Use background interrupt stepping (default mode).

       Mode 2:      Same as mode 1, plus conditional timer stepping.

       Mode 3:      Same as mode 1, plus unconditional timer stepping.

       Mode 1 relies on the underlying TSR mechanism, TesSeRact, to
       determine when it is absolutely safe to interrupt DOS in order to
       play.

       Mode 2 adds use of the system timer (about 18 ticks per second)
       to advance play.  This permits play to continue while running
       programs which otherwise would not allow Play/D to operate at
       all.  Any DOS activity will temporarily suspend play, however. 
       See warnings for mode 3 below. 

       Mode 3 combines idle time processing with forced timer stepping
       to assure high accuracy and continuous play regardless of other
       system activity.  While it is unlikely that timer interrupts will
       cause any problems, this is technically "unsafe".

       Users of 2/3/486 processors may select an additional command line
       option, -c, to specify AT real-time clock usage, in which case
       the mode 2 and 3 interrupt interval changes to 5 milliseconds.


-l     Specifies that LIM EMS (expanded memory) is to be used for MIDI file
       storage if available.  This reduces the resident size of Play/D.


-d     Specifies the type of MIDI interface in use.  Also, it is used to
       give additional information about the device if a non-standard setup
       is being used.  For the majority of users, this option will not be
       needed.  The supported MIDI interfaces are listed below.  Use -d,
       followed by the device name as shown to select one.

         Roland MPU-401 and compatibles               -dmpu
         IBM PC Music Feature                         -dmfc
         Sound Blaster MIDI interface                 -dsbmidi
         Key Electronics MIDIator                     -dmidiator

         The first 3 letters of the device name are sufficient.

       Note: The MIDIator cannot be detected automatically and the
       -dmid option must always be specified if one is in use.

       Non-standard IRQ and I/O port information can be added
       following the device id if necessary:   -d<dev>:<irq>:<ioaddr>

       For example, to define an MPU-compatible interface using IRQ 5
       and I/O address 336 (hex), use:  -dmpu:5:336
       If only the I/O address was required but the default IRQ was
       alright, use:  -dmpu::336

       The irq and ioaddr are not relevant to the MIDIator, though the
       first option number can be given to indicate use of com port 2
       instead of the default com 1.  (ex: -dmid:2)


-v     Shows the MIDI device, I/O address, and IRQ number selected prior
       to program startup.  You may wish to include this option if you
       suspect that automatic detection is not choosing the desired options,
       or to verify the IRQ being used.


-s     Determines the size of the MIDI receive buffer.  Follow -s with
       a number up to 63, indicating the size of the buffer in K bytes
       (1K=1024 bytes).  By default, no buffer is used, and Play/D operates
       in polled input mode.


Using environment variables:

Since it may be inconvenient to add these options every time Play/D is
run, options may be set up ahead of time through the use of DOS environment
variables.  A pool of environment variables named "opt1" through "opt9" are
available.  Pick any of the 9 available variables for the options which you
would like to preset.  For example, if you would normally use -dmpu:5 and
-m2, you could use the DOS set command as follows:

             set opt1=-dmpu:5
             set opt2=-m2