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From: wilt@killer.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Writing TSR's
Message-ID: <1722@killer.UUCP>
Date: Sat, 3-Oct-87 12:37:42 EDT
Article-I.D.: killer.1722
Posted: Sat Oct  3 12:37:42 1987
Date-Received: Sun, 4-Oct-87 07:24:31 EDT
Organization: The Unix(R) Connection, Dallas, Texas
Lines: 26
Keywords: TSR C Assembly

I have recently been trying to write a TSR that will allow our company to
take information off the screen and store it into a file.  I have slowly but
surely found out what I need to do.  However, I have continued to run into
snags because there seems to be "just one more" thing to keep the program
from crashing.  Does anyone out there have a definitive list of internal
PC/MSDOS locations that must be checked?  Following is a list of things I know
that I need to do for the TSR and the things I still need to find out:

Already taken care of:
1.  Saving the interrupt vector addresses and inserting new ones.
2.  Setting up the necessary C segments for a .COM file.
3.  Checking the INDOS flags (Both the one returned by INT 21h Function 34H,
    and the DOS critical flag).
4.  Setting up an internal stack.
5.  Checking the flags to see if can execute.

Remaining problems:
1.  Since I need to write to disk from within the TSR, I need to know if any
    other tasks must be completed.
2.  I can call my TSR while in DOS or DEBUG, but if I try to call from within
    my text editor (z from Manx Software) my machine locks up big time.

Please send me a definitive, but minimal, list of the tasks which I must com-
plete before my program will run.  Please send replies via E-mail.  I will
summarize and post to net if enough interest!  Thanks, 
Paul Wilt