Date: Thu, 18 Dec 1997 17:19:05 -0800 (PST)
Message-Id: <199712190119.RAA12044@adit.ap.net>
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To: Anthony DOT Appleyard AT umist DOT ac DOT uk, djgpp AT delorie DOT com
From: Nate Eldredge <eldredge AT ap DOT net>
Subject: Re: assembler; reading keyboard events by hooking int09
Precedence: bulk

At 11:55  12/18/1997 GMT, Anthony.Appleyard wrote:
>Query: When a TSR is set up, it seems that the installer program's PSP remains
>as 256 dead bytes taking up space below the TSR. Would any disaster happen if
>the interrupt handler in the TSR used this dead PSP as working space? How
>would the DOS instruction MEM react if such an old embedded PSP was corrupted?
I'm pretty sure you can overwrite at least the part with the command line
(128 bytes starting at offset 0x80), but I would be very hesitant to mess
with the rest. Looking at the structure of the PSP, several fields seem to
have no meaning to anything except DOS; the implication is that DOS uses
them and would probably be very unhappy if they were changed.

Nate Eldredge
eldredge AT ap DOT net