[Coco] Just a thought‏

[Mark McDougall]

On 13/05/2015 9:18 PM, Francis Swygert wrote:

> Instead of Motorola dumping the 6809 Machine Language and Registers model
> w/ the 68000 they would have in essence done what Intel did w/ the 8086 -
> made the 80186/286/386/486/Pentium etc...

Radio shack were not in the business of designing CPU's - that is a whole 
other ball game and they simply did not have the talent nor the resources.

> I remember feeling cheated when I
> first read in Byte Magazine how the 68000 assembly language and registers
> were completely different than the 6809 - why the 68xxx moniker then?

True, but the 68K is a _really_ nice chip to program with!

> Some of my favorite and most popular arcade games of all time
> (i.e. Defender and others) were running on 6809 chips around that same
> time period - imagine a computer that could run games of that caliber at
> home in the day?

It may interest you to know that Defender hardware was actually inferior to 
the Coco 3. A 1MHz 6809, plain bit-mapped graphics. Some bank-switching for 
ROMs but very little else in way of hardware.

> Running an 8088 program on a modern computer can only be done
> through a virtual machine.

And that makes sense. Building in such back-reaching compatibility into the 
hardware *will* impact the design adversely to some degree (and no doubt 
more-so as the years progress), and when you're running 2GHz+ processor it 
makes much, much more sense to emulate an 8MHz machine in software.

> They did
> sort fo drop the ball when making the CoCo3,

I think it's universally agreed that the Coco 3 was too little, too late.

Regards,

-- 
|              Mark McDougall                | "Electrical Engineers do it
|  <http://members.iinet.net.au/~msmcdoug>   |   with less resistance!"