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From: dvukovic@csn.org (Donald VuKovic)
Subject: Re: 68HC11 vs. 8080...etc
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Date: Wed, 2 Feb 1994 09:40:25 GMT
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PETER W. ELLISON (pwelliso@major.cs.mtu.edu) wrote:
<snip>
: Can some one post some more details on the INTEL products (past application,
: thoughts, feelings ...) ???


I use both the HC11 and '51 is all sorts of projects.

Last year (1993) we did four '51 projects and one HC11 project.

The projects useing the '51, were prety brain dead. One was a pump/value
timer/controller. This project needed to be as cheap and as small as possible.
A single 87c51 did the entire project. Mylar keypads ( 10 inputs ) on one
side of the chip and 6 opto triacs on the other side. Some very simple
software ( we use Archimedes C compilers ) got the project running with
out every seeing a single op-code. The project took 4 weeks after the spec
was written to finished prototype. Four more weeks to get a layout and
turn some boards. 25 units were in the clients hands before they could get
the color scheme for the brochures. (sales people... ;-)

The project should ditcate what processor you should use, not what you
feel you would like to work (play) with. 

The speed of the '51 family is not great. But once you truly understand
the problem you wish to solve, any processor may do the job.

The hc11 project is a PID controller for a pressure controller. The 2Mhz
thruput of the HC11 was really needed to get this project done on time.
Software was all written in C ( Archimedes again ).

Writting software on a PC in Turbo C to test any algrothms before
inserting the code into the controller board helps. Be sure you keep in
mind that you keep the same type of variables in the Turbo C code as in
the target system. ( you can do a lot of this on any PC that you can never
do with a uP ).

Some things to remember:

1) In many microcontroller you have only 128 BYTEs of memory.
	This means you have to check how much the compiler needs to run as
well as how many variables you can use.

2) Most compilers will have librarys that may do what you want to do.
	But, they may not be written in a way that will help you.
	( ie speed or memory usage ) 

3) A C compiler will help you keep track of all your memory and ROM usage.
	I know somebody will say that 'I do all my programming in
assembly and do just fine'. But if you quiz these people you will find
that they have a library of working code that they reuse from project to
project. ( sounds like a compiler doesn't it ;-)

We have done over 50 micro-computer projects useing all of the 8-bit
processors and most of the 16-bit processors on the market. The specs will
tell you which processor to use ( once you know the differance ;-)


thanks for listening
donaldV

PS: be sure to develop a spec in writting.
    If it ain't writ, it don't get done.

