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From: jer@ipmoea.UUCP (Eric Roskos)
Newsgroups: comp.arch
Subject: Re: byte order: be reasonable - do it my way...
Message-ID: <1@ipmoea.UUCP>
Date: Fri, 16-Jan-87 19:00:00 EST
Article-I.D.: ipmoea.1
Posted: Fri Jan 16 19:00:00 1987
Date-Received: Tue, 20-Jan-87 22:45:22 EST
References: <760@orcisi.UUCP>
Reply-To: jer@ipmoea.UUCP (Eric Roskos)
Organization: None
Lines: 26

uri@orcisi.UUCP writes:

>My point is that the Least-Significant-Byte-first camp (LSBians,
>pronounced: elesbians) has a more correct way than the Most-Significant-byte-
>first (MSBians, pronounced: emesbians), and I am going to try to convince
>the MSBians to go my way. 

It seems to me that the basic premise of the argument that follows the above
statement is that the name (memory address) bound to a long word in memory
is different from the name bound to its least significant byte, whereas
the same name (register number) references a longword (for a
long register operand) or its least significant byte (for a byte operand).
The poster argues that this is inconsistent.

In fact, the problem (and the cause of the whole debate, I often think) is that
separate bytes in a longword in memory have different names bound to them
at all.  What is the 2nd byte of a 4-byte integer good for, on its own?
Why should it be separately addressable at all?  

In the 68000, registers, however transiently, have a type associated with
them that determines their length; but the individual bytes of a register,
when it's a longword register, do not have separate names.
Register 5 is register 5, though its size varies depending on its type
(which persists only for the duration of 1 instruction).  Most problems
arise when you take a datum of one type and suddenly start treating it
as a different type; that is the real inconsistency.