Mailinglist Archive: opensuse (3434 mails)

[James Knott <james.knott@xxxxxxxxxx>]

Aaron Kulkis wrote:
> James Knott wrote:
> > Aaron Kulkis wrote:
> >
> > > A true modem doesn't have an on-board CPU.
> > > Not even 56k modems using frequency, amplitude, and phase shifting.
> > > There are hybrid digital/analog ICs (integrated circuits) which
> > > dothis right from the factory, needing only connectivity to power,
> > > a few external discreet elements (resistors, capacitors and/or
> >
> > I think you'll find even those chips have an embedded CPU in 'em.
>
> Those CPUs are only to implement the Hayes command set,
> and those don't need any external drivers, either,
> because the programming needed to run that is all
> self-contained in some sort of ROM (seperate, or
> on-chip if it's something like a Motorola 68HC11
> microcontroller.

There's more than just the command set.  Modems are also capable of data
compression & error detection among other things, that while technically
possible with custom logic are simply easier to implement in a CPU. 
BTW, what do you think is at the heart of a microcontroller?  A
microcontroller has a CPU, memory and I/O all built into one package. 
Take a look at this info on the 68HC11:
http://bd.thrijswijk.nl/mcca1/68hc11_intro.htm   A designer who needs a
custom chip will take a microcontroller and program it to do what he
wants, slap a new part number on it and ship it in a product.


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