Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ukma!rutgers!att!mtunb!dmt
From: dmt@mtunb.ATT.COM (Dave Tutelman)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Intra Applications Communication Area - Help?
Keywords: ICA
Message-ID: <1383@mtunb.ATT.COM>
Date: 31 Jan 89 13:09:44 GMT
References: <32985@tut.cis.ohio-state.edu> <242@donk.UUCP> <10997@s.ms.uky.edu>
Reply-To: dmt@mtunb.UUCP (Dave Tutelman)
Distribution: na
Organization: AT&T Bell Labs - Lincroft, NJ
Lines: 37

Answers from Norton's book, p.58:

In article <10997@s.ms.uky.edu> simon@ms.uky.edu (Simon Gales) writes:
>
>How large is this area?  
	16 bytes.  (not much.  Enough for a few pointers perhaps.)

>Does DOS ever touch it?  
	No, but some applications do.  Norton cites IBM Async Comm,
	Volkswriter, and TimeMark.

>Any warnings before I go and use it?  
	Note that the name is INTRA-application, not INTER-application.
	It's intended to be used by multiple executables in THE SAME
	application.  Don't count on long-term stability of the data;
	when you run another app, it may change the data.  In fact, Norton
	recommends including a signature and checksum to assure its
	integrity.  I see some limitations to this strategy:
	   -	There's very little room for it.
	   -	If you restrict yourself to ONLY a single running of
		one application, you're only vulnerable to apps that
		use the data area on an interrupt (say, a TSR).  I
		know of no such apps, BUT if they existed....
	   -	...you'd have to disable interrupts to maintain the
		checksum/read-data pair as an incorruptible atomic
		unit.

>Is this place set up by the BIOS or by DOS?
	It's at the end of the BIOS data area.


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