Path: utzoo!attcan!uunet!cs.utexas.edu!usc!apple!motcsd!mcdcup!mcdchg!ddsw1!corpane!herman
From: herman@corpane.UUCP (Harry Herman)
Newsgroups: comp.misc
Subject: Re: Wanted: easter eggs
Message-ID: <2629@corpane.UUCP>
Date: 20 Jul 90 23:00:23 GMT
References: <31567@cup.portal.com> <3021@unocss.unomaha.edu>
Distribution: na
Organization: Corpane Industries, Inc., Louisville Ky
Lines: 36

In <3021@unocss.unomaha.edu> mlewis@unocss.unomaha.edu (mlewis) writes:

>From article <31567@cup.portal.com>, by dbell@cup.portal.com (David J Bell):


>> remember what, when I spotted the string "XYZZY". That looks
>> familiar, I mumbled; what if I tried it as a command? Sure enough,
>> instead of the expected "Syntax Error", it responded "I see no caves here."


>Data General's AOS and AOS/VS CLI (Command Line Interpreter) responds to
>XYZZY with a simple 'nothing happens'

>Marc

Heathkit used to make an 8080 based system called the H-8.  The operating
system consisted of a core image and two overlay regions (originally just
one overlay region).  The system call dispatcher had a table of which
calls were in the core and which were in the overlay(s).  If an overlay
was needed, the overlay was read in and the function was executed.  In
order to support single disk drive operation and allow you to switch
disks, the command interpretter had an undocumented command to cause the
operating system to load the overlay(s) permanently into memory, which
naturally reduced the space available for your program.  When you executed
this command, the command interpretter printed "It is now pitch dark.  If
you proceed you will likely fall into a pit.", or something similar.

In one of the later releases, they added a new system call that allowed
you to load either of the overlays under program control, and either
have them stay resident until the space was needed for something else, or
have them become permanently resident.  Of course you did not get the
message if you loaded them yourself.

					Harry Herman
					herman@corpane	or
					..uunet!corpane!herman