Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!dogie.macc.wisc.edu!uwvax!shorty!rose
From: rose@shorty.CS.WISC.EDU (Scott Rose)
Newsgroups: comp.sys.ibm.pc
Subject: Where does it all start: memory control blocks?
Message-ID: <7495@spool.cs.wisc.edu>
Date: 9 May 89 14:35:34 GMT
Sender: news@spool.cs.wisc.edu
Reply-To: rose@shorty.WISC.EDU (Scott Rose)
Distribution: na
Organization: U of Wisconsin CS Dept
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1. For various reasons too ugly to publicly admit, I wish to be able to follow
the chain of memory control blocks.  I have a very lovely little program that
does just that, and in a very informative fashion: mapmem, particularly
useful in conjunction with its /v switch.  It works every time, which is
evidence that if an entirely elegant technique is not available there is at
least some repeatable way to find the head of the chain.  While I can
find *some* of the MCBs- that associated with the PSP of my program and any
that follow- these beasties are not doubly-linked, and no documentation that
I have found describes how to find the root.

2. Another lovely little program that has fallen into my hands keeps a little
queue of events in memory and eyes the system clock to determine when to 
execute one.  Called 'at', it only executes a job if it is determined that
the machine is at the DOS prompt.  HOW DOES IT KNOW?

3. Alright, I've asked this before... How, specifically, do I move back into
real from protected mode, on an AT?  Yes, I know, it requires a reset.  Yes,
there is a way to get the keyboard to generate the required signal.  Yes, a
PC Tech article back in 1985 tells just how to do it.  I don't have access
to this issue of PC Tech (you remember PC Tech, don't you?), and *still* want
to know how to do this?

Thanks, in advance, to anybody who can provide me with answer(s) to these
burning questions of the day.