Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!boulder!ccncsu!longs.LANCE.ColoState.Edu!gs940971
From: gs940971@longs.LANCE.ColoState.Edu (glen sunada f84)
Newsgroups: comp.sys.ibm.pc
Subject: Re: HELP! Using DOS print
Message-ID: <3296@ccncsu.ColoState.EDU>
Date: 29 Nov 89 17:13:18 GMT
References: <3289@ccncsu.ColoState.EDU> <6534@brspyr1.BRS.Com>
Sender: news@ccncsu.ColoState.EDU
Reply-To: gs940971@longs.LANCE.ColoState.Edu (glen sunada f84)
Distribution: usa
Organization: Colorado State U. Center for Computer Assisted Engineering
Lines: 52

In my article I expressed ignorence to the mechanism used to communicate
with print
I recieved a mail message from Raymond Chen at Berkley that set me on
the correct path
to locateing that method.  I then looked up the specifics in the Waite Group's
_MS-DOS Developers Guide_ Second editions.

What follows is my reply to him:

>>Print uses some mechanism to detect if it is already resident to prevent
>>multiple copies of the resident code.  I do not know how this is done
>
>It installs itself into the DOS multiplex interrupt (Int 21, ah = 2f,
>I think).  This is a quasi-standard way of checking for multiple
>installations, once you get an official multiplex ID number.

I found my DOS reference and print does install itself on the DOS
Multiplex interrupts.
That is interruipt 2f.  The calling parameters for interrupt 2f are as follows.

    AH = program code (supplied DOS codes as folows)
          01 - print
          02 - assign
          10 - share
          b7 - append
   
    AL = requested function code
          00 - get installed state (all)
          01 - submit file to print
               DS:DX = pointer to submit packet
                       0 + DWORD pointer to ASCIIZ filespec
          02 - cancel file in print queue
               DS:DX = pointer to fully qualified (no wild card) ASCIIZ
filespec
                       to cancel
          03 - Cancel all files in print queue
          04 - pause print and return status
               (I don't know the return codes here)
          05 - end of print status
               (I don't know these reutrns either)

    Gaurenteed return codes
    if CF = 1 AX = error code
    if AL = 0FF a program with your identifier is installed
    if AL =   0 no program with your identifer installed ok to install
    if AL =   1 no program with your identifer installed not ok to install

Glen Sunada
gs940971@longs.LANCE.ColoState.EDU    ARPA Internet (preferred)
...ncar!boulder!ccncsu!longs.LANCE.ColoState.EDU!gs940971 UUCP

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