Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!mcsun!ukc!edcastle!ercm20
From: ercm20@castle.ed.ac.uk (Sam Wilson)
Newsgroups: alt.folklore.computers
Subject: Re: Y VAX? [was : TECO on a DEC-System 10]
Message-ID: <1665@castle.ed.ac.uk>
Date: 17 Jan 90 12:44:21 GMT
References: <34346@mips.mips.COM> <147.UUL1.3#5131@mvac23.UUCP> <50898@bbn.COM> <1990Jan16.065338.24185@world.std.com>
Reply-To: ercm20@castle.ed.ac.uk (Sam Wilson)
Organization: Edinburgh University Computing Service
Lines: 12

[What does VAX stand for?  Someone answered 'Virtual Address eXtension.]

Virtual Address eXtension it is! The PDP 11/34 that I used to work on
had an 18-bit real memory address.  Some of the other 11s had 22-bit
real memory addresses.  The instruction set of all 11s has 16-bit
addresses, referred to in the memory manager dox as the virtual address. 
So the virtual address space was SMALLER than the real address space,
that's why, when they built the VAX as an upgrade to the 11, they
decided it needed an eXtension! :-)

Sam Wilson				Dislaimer: Wisnae me, Jum!
Edinburgh University