Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!accuvax.nwu.edu!tank!eecae!cps3xx!cpsvax!dulimart
From: dulimart@cpsvax.cps.msu.edu (Hansye S. Dulimarta)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Help from TSR Gurus requested
Keywords: TSR, PSP, Process, Allocation
Message-ID: <3845@cps3xx.UUCP>
Date: 18 Jul 89 21:07:55 GMT
References: <536@cybaswan.UUCP>
Sender: usenet@cps3xx.UUCP
Reply-To: dulimart@cpsvax.UUCP (Hansye S. Dulimarta)
Organization: Michigan State University, Computer Science Department
Lines: 21

In article <536@cybaswan.UUCP> iiit-sh@cybaswan.UUCP (Steve Hosgood) writes:
>[deleted stuff...]
>Now the Question: Can the resident part of a TSR get away with using the area
>below 5Ch? I would *think* that DOS has no further use for the PSP after the
>program becomes resident, but of course the area may still figure
>in some sort of linked-list internally in DOS.
>
>Steve

Once you hooked up your TSR routine to any interrupt handler, the PSP is not
used anymore. BTW, I knew a TSR routine which used its PSP to store the old
vector interrupt address it handles.
Also remeber the way we put our routine into TSR, by calling DOS call
(int 21h function 31h or by int 27h), in these calls we have to specify
the address which we want to be resident in memory. The PSP is below this
address, but of course our interrupt handler's entry point is not exactly
at the PSP, instead the entry point is somewhere _after_ the PSP.

Hope it helps.

Hans.