Digitalker, SP0256, and SC-01 speech chips

[Dave McGuire]

On Feb 14, 2008, at 8:56 PM, Chuck Guzis wrote:
>>    Doubtful, as it's just the same architecture, and far from the
>> same implementation.  The 8X30x chips are bipolar, if memory  
>> serves.   But
>> either way, I'm not sure what the point would be, aside from   
>> possibly
>> building new boards using an existing 8X30x MSCP  implementation.
>
> As one who has had the extreme displeasure of programming both the
> 8X300 and an 8X305,

   Are they really that bad?  How so?

> I'd have to say that the two have about as much
> in common with a PIC as a pocket knife to an CNC EDM system.  The
> instruction sets aren't even close, nor is the data path
> architecture.  In some respects, the bipolar chip has a bit more
> flexibility (e.g. variable-length operations and an "execute"
> instruction) even with its limitation of an instruction set of size
> 8.
...
> Do you have a cite that states that the PIC1640 is a direct
> descendent of the SMS 300?  Microchip certainly doesn't admit it--and
> I'd be hard pressed to find the similarity beyond both being Harvard
> architecture binary CPUs.

   I went to gather references and I found that I may have  
misunderstood something a very long time ago!  Here's a quote from  
the PIC FAQ:

> The roots of the PIC originated at Harvard university for a Defense  
> Department project, but was beaten by a simpler (and more reliable  
> at the time) single memory design from Princeton. Harvard  
> Architecture was first used in the Signetics 8x300, and was adapted  
> by General Instruments for use as a peripheral interface controller  
> (PIC) which was designed to compensate for poor I/O in its 16 bit  
> CP1600 CPU. The microelectronics division was eventually spun off  
> into Arizona Microchip Technology (around 1985), with the PIC as  
> its main product.

   I (more than a decade ago) took that to mean that the processor  
architecture (the instruction set and register layout, not just  
"Harvard") was traced back to the 8X300.  It was *Harvard  
architecture* that was used by GI, not the 8X300 architecture...does  
that make more sense?  In that case, I stand corrected and apologize  
for my error!

   That said, what can you tell us about the 8X30x processors?  I  
don't think I've ever known anyone else who designed with them.

            -Dave

-- 
Dave McGuire
Port Charlotte, FL