In message 
<0...@c58g2000hsc.googlegroups.com>, 
Tomás Ó hÉilidhe <t...@lavabit.com> writes
>On Jun 1, 2:00 am, Jim Granville <no.s...@designtools.maps.co.nz>
>wrote:
>
>> The most used CORE, by far, is the 80C51.
>
>
>By "core", do you mean the processing of instructions? If two
>microcontrollers have the same set of assembler instructions, then are
>they said to have the same core?

Sort of.
As far as most programmers are concerned the 8051is a family with the 
same core as code that runs on one will run on another, even at a binary 
level... but why am I telling you this as you are the resident genius on 
portability...

In fact for the 8051 family there are over 40 cores currently in use. 
Whilst the basic instruction set and the basic core has the same API 
they are very different being 12, 6, 4, 2 and single cycle cores with 
several different memory systems.   Especially the extended ones...

There is a Lot more to it than  just changing header files.

However whilst, if you are careful a small program from one 8051 will 
run on any 8051.... but once you start using the peripherals and 
extended memory and registers you loose the portability even though you 
can use the came compiler for all variants. .

>> The largest 8 bit uC vendor by dollars is Freescale, and by volume is
>> Microchip.
>When you say Microchip, are you talking about PIC chips,

Wow!  Your lack of knowledge even on the things you have worked on is 
astounding!!!

When some one tells you that you don't have the first idea about 
portable C you really only argued because you had so little grasp and 
understanding of the subject.  I hope you realise that now.

> e.g. the
>PIC16F684? Is the PIC really the most ubiquitious uC?

No.  But PICs in general might be. They are very low cost small parts. 
Though about  8 years ago the 8051 family was the most ubiquitous with 
about 30% of all  micros (including the x86 family as most PC's up to 
then had a couple of 8051's in them)

>So do Freescale make more advanced uC's that cost more?

Yes... The Power PC range.
http://www.freescale.com/webapp/sps/site/homepage.jsp?nodeId=0162468rH3bT
dG

BTW what is your collage course on?
It does not appear to be on software or electronics.

-- 
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
\/\/\/\/\ Chris Hills  Staffs  England     /\/\/\/\/
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/

On Sun, 1 Jun 2008 04:10:07 -0700 (PDT), Tomás Ó hÉilidhe
<t...@lavabit.com> wrote:

>On Jun 1, 1:19 am, Rich Webb <bbew...@mapson.nozirev.ten> wrote:
>
>> Personal preferences:
>> 8 bits: AVR
>> 16 bits: MSP430
>> 32 bits: NXP's LPC2xxx ARM7s
>
>
>What influences your choice of 8-Bit, 16-Bit or 32-Bit? Is one more
>expensive than the other? I understand that if you're commonly dealing
>with 32-Bit numbers on an 8-Bit uC, that you'll be using 4
>instructions (at least) all the time instead of 1. So, before
>embarking on the project, do you have a think about what kind of
>numbers you'll be working with?
>
>I've only ever done one full embedded project and I didn't use
>anything larger than an 8-Bit number. However, if I were making
>something like an internet router, would I be wise to get a 32-Bit
>microcontroller because I'd be dealing with IP addresses all the time?
>Or then again, what if I can find an 8-Bit CPU that runs 6 times
>faster and is half the price... would I be better going with that?
>
>What other reasons are there for deciding on bitness of the core?

Essentially, matching the requirements and constraints to the
solution. Engineering, ya know. What parts are actually available? Is
EOL an issue, and what's the manufacturer's EOL history? What's the
cost? The lifecycle quantity? Production quantity? Should we spin our
own board or use somebody else's? What peripherals are needed? How
complex is it? What tools are available? Cost? How are they supported?
Personal project, where free is good and the GPL isn't an issue or
commercial where it may be?

An ATtiny15 that has 8 pins and no RAM at all, just the processor
registers and a 3-level stack, was great for a little temperature
monitor and fan controller.

OTOH, an Infineon C515C (MCS51-family) was the solution for something
else because it was living on the best-fit SBC.

For a CAN gateway, is it better to use a couple of small 8-bitters
with one CAN controller each and an SPI link between them, or an ARM
with two integral CAN controllers? It depends ...

-- 
Rich Webb     Norfolk, VA

In article <0246d634-8d49-44b5-b35c-
5...@j22g2000hsf.googlegroups.com>, Tomás Ó hÉilidhe says...
> On Jun 1, 1:16 am, Robert Adsett <s...@aeolusdevelopment.com> wrote:
> 
> > > I mean if I
> > > programmed one now and put it in a circuit, should it still be doing
> > > its job perfectly in 80 years time?
> >
> > I doubt any manufacturer would be willing to give you that assurance.  I
> > don't remember seeing any flash memory with a quoted lifetime beyond 20
> > years.
> >
> > Jack Gansle had an article a decade back or so IIRC about running into
> > that issue with some of the original Intel EPROMs in the field.
> 
> But aren't the old PC's like the 286's still running perfectly? Or are
> they on the brink of failure in the next few years?

I don't think I've seen an original 286 PC still running.  Usually the 
power supply will fail at some point, often leading to damage to 
everything else.  Most are retired from service before having a chance 
to die of old age.

> I've got two cars at the moment, one is from 1990 and the other is
> from 1991, and they're both running well. That's an 18-year-old car
> and a 17-year-old car. Granted, one of them is a Toyota and is a much
> nicer driver than the other, but they're both still running well.

And I take it you've had no maintenance performed on them? You've never 
replaced the tires?  

> Would it be fair to say that today's cars won't last as long because
> of all the electronics in them? Will the engine's electronic
> management unit fail before the engine does?

That has been remarked on before.  Unlike early automobiles where parts 
can be duplicated even though they are no longer in manufacture it will 
less possible to duplicate the higher end electronics in more modern 
vehicles.  Electronics in the engine compartment are obviously at higher 
risk.

You perform routine maintainence on an engine but when a micro processor 
board fails your only alternative is replacement.
 
Heat, temperature cycles, radiation, power supply spikes all take their 
toll.  If you want assurance of an 80 year life you will have to be 
prepared to do the testing to determine which parts are capable of 
supporting it.  And expect to retest continually to make sure process 
changes haven't affected the undocumented margin.  

Besides which how many electronics devices actually still have a purpose 
over that period?  They have usually been replaced by something more 
capable or less expensive (or just dissapeared from use).  

Although memory is a prime culprit for limiting life (due to charge 
leakage for instance), power supplies are vulnerable as well due to 
exposure to spikes, high operating temperature and of course the drying 
of electrolytes.  There has also been some speculation that the upcoming 
generations of high end microprocessors may be subject to wearout 
because of the high operating temperature coupled with increasingly fine 
geometries. 

Another thing to keep in mind is the operating environment.  Check the 
datasheet, lifetime will be specified under certain operating 
conditions.  Generally as a designer you cannot guarantee a benign 
operating environment.  Remember those Abs Max conditions?  They come 
into play again.

Robert
** Posted from http://www.teranews.com **

Tomás Ó hÉilidhe wrote:
> On Jun 1, 2:00 am, Jim Granville <no.s...@designtools.maps.co.nz>
> wrote:
> 
> 
>>The most used CORE, by far, is the 80C51.
> 
> By "core", do you mean the processing of instructions? If two
> microcontrollers have the same set of assembler instructions, then are
> they said to have the same core?

  Normally, if they run the same binary opcodes, then they are said
to be binary-compatible, and must be definiion, be 'the same core'.
(some 8051 cores run at different speeds, but can still execute
the same hex file - just like your PC.)
> 
> 
>>The largest 8 bit uC vendor by dollars is Freescale, and by volume is
>>Microchip.
> 
> 
> When you say Microchip, are you talking about PIC chips, e.g. the
> PIC16F684? Is the PIC really the most ubiquitious uC?

PIC is the highest volume brand name, but the PIC brand covers many 
different cores, (there is NO single PIC core), so they are not really 
the same product.


> So do Freescale make more advanced uC's that cost more?

Yes, the Freescale ASP (average selling price) is quite a bit
higher than Microchip, which still has ASP very close to $1.

-jg