Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10 beta 3/9/83; site vaxine.UUCP
Path: utzoo!linus!vaxine!ptw
From: ptw@vaxine.UUCP (P. Tucker Withington)
Newsgroups: net.arch
Subject: Re: uP architecture - (nf)
Message-ID: <241@vaxine.UUCP>
Date: Tue, 5-Jul-83 10:55:39 EDT
Article-I.D.: vaxine.241
Posted: Tue Jul  5 10:55:39 1983
Date-Received: Thu, 7-Jul-83 11:40:34 EDT
References: <4745@cornell.UUCP>
Organization: Automatix Inc., Billerica, MA
Lines: 27

Personal opinion only and no offense...

I think that unfortunately the first microprocessors were doomed to reinvent
the wheel because hardware and software were still separate disciplines at
that time.  To a software type, the first u-cpu's looked like nothing more
than a hardware type's attempt to formalize the finite state machines they had
been building out of shift registers for years.  The u-cpu instruction set was
an accident of the Karnaugh map.

Yes, the 4004 fell out of a contract to build a shift register for a
calculator and the 8008 out of a contract for a CRT controller.  Their use a
cpu's was mostly fortuitous, as the many early programming hacks to implement
stack disciplines (and register saves) make evident.

The 6800/6502 were the first move to attempt to profit by the the existing
knowledge of u-computers, and were modelled on the 11, within the limits of
technology at the time.  The 6502 group split off because they saw the limits
as not as restrictive as the 6800 implementation would make one think.

It's unfortunate that the [Z]80[.*] is a slave to upward compatibility, given
its feeble root stock.  It's unfortunate that the 6809 was left in the dust of
its younger and abler cousin.  But that's history and we can't really complain
about whats being produced now.  The 432 is even a little too advanced!

...end of personal opinion caveat.

				       --Tucker (ptw@vaxine.UUCP)