FILE MSPSPD.HLP          SERIAL PRINTER DRIVER                 September 1991

MSPSPD.ASM is a public domain serial printer driver for MS-DOS computers,
written by Frank Whaley in 1989 and found by Joe Doupnik in the mirror/printer
directory on wuarchive.wustl.edu.  The original name of the program was
XONXOFF; it has been renamed to MSPSPD to fit the Kermit Distribution naming
conventions.

MS-DOS allows you to define a COM port as a printer device using the MODE
command, for use with a serial printer, for example:

  MODE COM1:9600,N,8,1,P
  MODE LPT1:=COM1

However, MS-DOS does not provide flow control between itself and a serial
printer.  MS-DOS Kermit uses standard DOS calls for printer operations (print
screen, transparent print, autoprint, etc).  A common complaint is that these
print operations do not work well with serial printers -- characters are lost
or garbled, etc.

The MSPSPD program provides the needed flow control for serial printers.  It
works only for COM1 only.  It installs itself as a terminate-and-stay-resident
(TSR) program, intercepts DOS interrupt 17H, leaves the port baud rate and
other parameters as found (so you must set them with the MODE command), and
contains no provisions for de-installation.

The program is written in assembly language.  To build it:

  MASM MSPSPD;
  LINK MSPSPD;
  DEL MSPSPD.OBJ
  EXE2BIN MSPSPD.EXE MSPSPD.COM
  DEL MSPSPD.EXE

Then run it from your AUTOEXEC.BAT file after giving the necessary MODE
commands, for example:

  MODE COM1:9600,N,8,1,P
  MODE LPT1:=COM1
  C:\MSPSPD

For generality, this program needs to be modified to accept command line
arguments to specify which port address (and IRQ) to use, and to allow
deinstallation.  The normal port values are:

  Port  Address IRQ
  COM1   03F8H   4
  COM2   02F8H   3
  COM3   03220   3 (PS/2)
  COM4   03228   3 (PS/2)

NOTE: Non-PS/2s probably use different addresses and IRQs for COM3 and COM4.
If you make these modifications, be sure to send the improved program back
to Kermit Distribution at Columbia University so everybody can benefit from
your work.

[End of MSPSPD.HLP]