Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10 beta 3/9/83; site microsoft.UUCP
Path: utzoo!linus!decvax!tektronix!uw-beaver!microsoft!gordonl
From: gordonl@microsoft.UUCP (Gordon Letwin)
Newsgroups: net.arch
Subject: 8086 flag bit stylistics
Message-ID: <8725@microsoft.UUCP>
Date: Thu, 8-Nov-84 23:41:26 EST
Article-I.D.: microsof.8725
Posted: Thu Nov  8 23:41:26 1984
Date-Received: Sat, 10-Nov-84 21:28:31 EST
Organization: Microsoft Corporation
Lines: 10

Many "original-design mini" architectures set the flag bits often...
when a register is loaded, for example.  The PDP-11, by my recollection,
does this.

The 8086/286/386 family sets the registers only on logical/arithmetic
operations, not for loads,stores, and moves.  The reason for this dates
back to the 8080 which dates back to the 8008: to do any operation involving
more than 8 bits required a lot of moving around... if the moves modified
the flag bits (espeically CARRY) then multi-byte operations would have
been ruled out.