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From: darrylo@hpsrlc.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Re: Where to get started with TSR's
Message-ID: <3320069@hpsrlc.HP.COM>
Date: Fri, 20-Nov-87 11:27:20 EST
Article-I.D.: hpsrlc.3320069
Posted: Fri Nov 20 11:27:20 1987
Date-Received: Mon, 23-Nov-87 01:22:09 EST
References: <188@owlmnt.UUCP>
Organization: HP Network Measurements Div - Santa Rosa, CA
Lines: 33

In comp.sys.ibm.pc, jim@owlmnt.UUCP (Nite Owl) writes:

> I have to develop a system that sets up a background TSR to receive and transmit
> files from an async port.  I know how to do simple things with TSR's but I'm not
> sure about all the places where I might get burnt.
> 
> More specifically, what, if anything, do I need to do to be able to safely open
> and close files from a TSR?  Are the use of the DOS "Critical Region" flag and
> INT 28H enough?
> -- 
> 
> Jim McCool
> Owl Mountain Inc.
> Usenet: wright!owlmnt!jim
> ----------

     Writing a reliable TSR that does DOS calls, etc. is not much different
than opening pandora's box.  Not only should the "INDOS" flag be checked,
but you have to make sure that a video or keyboard interrupt is not in
progress (among many other things).

     If you or anyone is interested, I have some examples on how to write a
TSR, some written in assembly (TSRDEMO.ASM, TSRDEMO2.ASM, & TSRSH.ASM) and
one written in Turbo Pascal V3.0 (STAYRES 4.2).  If you want a copy, send
Email.

     -- Darryl Okahata
	{hplabs!hpccc!, hpfcla!} hpsrla!darrylo
	CompuServe: 75206,3074

Disclaimer: the above is the author's personal opinion and is not the
opinion or policy of his employer or of the little green men that
have been following him all day.