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From: "Mark Habersack" <grendel AT hoth DOT amu DOT edu DOT pl>
Organization: PPP (Pesticide Powered Pumpkins)
To: "Colin W. Glenn" <cwg01 AT gnofn DOT org>
Date: Sat, 15 Mar 1997 18:36:42 +0100
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Subject: Re: [opendos] IOSYS Magic?
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On 14 Mar 97 (at 22:09) Colin W. Glenn became famous by saying:

> > loaded up or high - the the shell goes there as well) while the transient
> > portion is pushed up towards the end of TPA to protect it from being
> > overwritten too 
> 
> Command.com does this itself, says so in the DOS Programmer's reference,
> pages 56-57.  I psuedo-quote:
> 
> After completing the initialization process, SYSINIT closes all file
> handles, opens CON for STDIN STDOUT STDERR, PRN as STDLIST, AUX as STDAUX.
> It then calls upon DOS EXEC to load and execute COMMAND.COM or (shell)..
> 
> When COMMAND.COM is loaded, it immediately relocates part of itself in
> high memory.  The low-memory section of C.C (the resident section)
> contains code for INT's 22h, 23h, 24h....
> 
> End psuedo-quote.
A moment... true that's right. So, it seems it *might* just might be 
possible... With some magic behind, of course

> > > shell have to meet certain requirements to be a shell?  Can a shell have
> > > a
> > I'm not sure, but I suspect the answer is yes. From what I investigated,
> > M$-DOG kernel does some undocummented calls into the shell on load time. 
> 
> How can the kernel make undocumented calls into (shell)?
AFAIR, there are many undocumented hooks in the shell during the startup - 
they are set up to establish a two-way communication between the OS and the 
shell. I remember to read it in some version of TechHelp (a thing I've lost 
ages ago and cannot find it anywhere now ;-(())

> > Besides try to set *any* program as a shell?
> 
> fraid not, not daring enough.
Point for you - it'd hurt...

> > > Inquiring minds need to know!
> > Inquiring minds join together! ;-)
> 
> Just watch out for brain bruises. ;)
Ouch! Hurts already ;_))

----------------------------------------------------------
Doctor said my liver looks like living with my lover -
needs another time-out now. Like any sort of hero turning
down to zero, standing out in any crowd. [snip]
Dr. Finlay: And my advice is if you maintain this lifestyle
you won't reach 30...