Re: 'Stuck' on one address?

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#686

From: da... David Landis
Date: Thu, 04 Jan 1990 19:25

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The IBM 1130 had 16 bit words, a 5 bit opcode with 3 modifier bits
filling out the first 8 bits, and an addressing scheme that wrapped
from the highest address back to zero.  It turned out that EBCDIC
blanks was a valid instruction, x'4040' == MDX *+64, a short branch
to the current address plus 64.  A short program to fill (clear) 
memory to 'spaces' would then loop forever, cycling through memory.
  
David E. Landis				University of Michigan
Sr. Research Programmer			3126 Argus I Building
Phone:  (313) 763-0592                  535 West William Street
Internet: da...@ifs.umich.edu		Ann Arbor, MI, 48103-4983

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Path: mbox-mo1.pugleaf.net!gmdzi!unido!mcsun!uunet!samsung!shadooby!terminator!ifs.umich.edu!davel

References: <4878@sugar.hackercorp.com> <1990Jan2.113240.4424@gdt.bath.ac.uk>

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Path: mbox-mo1.pugleaf.net!gmdzi!unido!mcsun!uunet!samsung!shadooby!terminator!ifs.umich.edu!davel
From: da...@ifs.umich.edu (David Landis)
Newsgroups: alt.folklore.computers
Subject: Re: 'Stuck' on one address?
Message-ID: <1990Jan4.192554.1101@terminator.cc.umich.edu>
Date: 4 Jan 90 19:25:54 GMT
References: <4878@sugar.hackercorp.com> <1990Jan2.113240.4424@gdt.bath.ac.uk>
Sender: ne...@terminator.cc.umich.edu
Reply-To: da...@ifs.umich.edu (David Landis)
Organization: University of Michigan, Institutional File System Project
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Posted: Thu Jan  4 20:25:54 1990
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