Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!wuarchive!gem.mps.ohio-state.edu!apple!baum
From: baum@Apple.COM (Allen J. Baum)
Newsgroups: comp.arch
Subject: Bootstrapping, was Self-modifying code
Message-ID: <35922@apple.Apple.COM>
Date: 25 Oct 89 22:27:06 GMT
Reply-To: baum@apple.UUCP (Allen Baum)
Organization: Apple Computer, Inc.
Lines: 11

[]
I once built a machine that had, as instruction 0x00, push i/o device 0 onto
the stack. The stack ran backwards. Bootstrapping started by clearing out
memory, and initializing the stack point and PC. The processor proceeded to
execute all zero instructions, which read bootstrapping code from the I/O
device and pushed it onto the stack. The PC continued to be incremented, the
stack continued to be decremented, and when the met, you took off. In
hindsight, of course, it would havebeen easier if the stack ran forward.
--
		  baum@apple.com		(408)974-3385
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