Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!uakari.primate.wisc.edu!aplcen!ginosko!uunet!lll-winken!tekbspa!optilink!elliott
From: elliott@optilink.UUCP (Paul Elliott x225)
Newsgroups: comp.realtime
Subject: Re: 80c51 vs. 68hc11
Summary: 68HC11 / 80C51 comparison
Keywords: realtime, 8051, 68hc11
Message-ID: <2316@optilink.UUCP>
Date: 12 Sep 89 16:54:32 GMT
References: <2127@uceng.UC.EDU>
Organization: Optilink Corporation, Petaluma, CA
Lines: 45

In article <2127@uceng.UC.EDU>, skohls@uceng.UC.EDU (Steve Kohls) writes:
> 
> 	I have a few questions for those out there that have used the
> 	Intel 80C51 or Motorola 68HC11 series of processors.


At Optilink, we evaluated the 80C51 and the 68HC11 for use on telecom
equipment linecards (literally hundreds per system) so our criteria were
somewhat different than yours, but for what it's worth...

80C51 advantages:
-Multiple sources.
-Faster interrupt response (the 68HC11 stacks all registers automatically,
 whether you need to or not).
-More mature product, therefor wider choice of development tools.

68HC11 advantages:
-More internal features (extra counters, async AND sync serial support,
 a-to-d converter, eeprom, etc.).
-Flexible startup (boot) options-- can be started out of eeprom, for example.
-Real stack (the 80C51 has a limited internal stack-- this might be a critical
 issue for a real-time kernal).
-Better external memory support (the HL register on the 80c51 is a bottleneck).

In the final analysis, we decided that the Motorola chip was a better fit for 
our application.  There are several c compilers for the 68HC11; we evaluated 
a handfull and found that the code generated ranged from pretty good to 
absolutely horrible (I can follow up on this if you are interested).

By the way, I have used the 80C51 in several projects in the past, and it
is an excellent chip where appropriate.  It just has some architectural 
features that optimize it for smaller controller jobs.

Good luck in your project!
--Paul





-- 
Paul M. Elliott      Optilink Corporation     (707) 795-9444
         {pyramid,pixar,tekbspa}!optilink!elliott
"I used to think I was indecisive, but now I'm not so sure."
Disclaimer: Like Horton, I meant what I said and I said what I meant.