Path: utzoo!attcan!uunet!crdgw1!steinmetz!sungod!davidsen
From: davidsen@sungod.steinmetz (William Davidsen)
Newsgroups: comp.arch
Subject: Re: 8086 design goals (and Pascal)
Message-ID: <13822@steinmetz.ge.com>
Date: 18 May 89 13:28:55 GMT
References: <912@aber-cs.UUCP> <3312@bd.sei.cmu.edu> <362@verdix.verdix.com> <15766@vail.ICO.ISC.COM> <370@telesoft.UUCP>
Sender: news@steinmetz.ge.com
Reply-To: davidsen@crdos1.UUCP (bill davidsen)
Organization: General Electric CRD, Schenectady, NY
Lines: 26

In article <370@telesoft.UUCP> roger@telesoft.UUCP (Roger Arnold @prodigal) writes:

| The 8085 was really a much better chip than Intel advertised.  The
| undocumented instructions extended the 8080 instruction set in what I
| considered to be a cleaner and more natural manner than the glitzier
| extensions in the Z80.  

  Agreed. I was maintaining a compiler at that time, and just went ahead
and put the extensions in. Having 2 byte indirect was a major win.

  At that time GE was designing a hardcopy terminal called the TermiNet
2000, and I sent a copy of the article in DDJ to Nelson Rosenstein in
Waynesboro. Some time later they sent me a copy of a contract between GE
and Intel for "a superset of the 8085 chip with added instructions."
If you ordered the GE part number you would get the instructions,
documented.

  I assume that Intel has not taken out the instructions, since that
would take a design effort.

  There were also (as I recall) 12 undocumented instructions in the Z80,
at least the Zylog version, of which only a few were useful to a sane
person. Some of the others were really neat, but not useful.
	bill davidsen		(davidsen@crdos1.crd.GE.COM)
  {uunet | philabs}!crdgw1!crdos1!davidsen
"Stupidity, like virtue, is its own reward" -me