[Coco] New 6821, 6551 replacements

[jdaggett at gate.net]

On 2 Feb 2009 at 15:20, Roger Taylor wrote:

> Here's a company we need to keep an eye on.  The Western Design
> Center, Inc. If they can do for the 6809 what they did for the 6502,
> (creating a 100+mhz and 200+mhz version), what an amazing thing this
> would be.

Be aware of when looking at cores that are intended for FPGAs. WHile they 
may very well claim to have 100+ MHz clock speeds, that may not very will 
be the same as machine cycle time. For example most CPU cores I have 
seen for FPGA uses two to four clocks per machine cycle. So if the FPGA 
clock is at 100MHz the actual machine cycle time is only 25 MHz with four 
clocks per machine cycle. 

I also noted that they quoted doing ASIC with 0.8 micron CMOS process to 
get their 14 MHz processor. I would rather believe that getting much faster 
than that will be hard for that old CMOS technology.  That was state of the 
art back in the 80's. Today the technology is at 0.045 micron. About 20 
times smaller. 

There used to be three different commercial cores for the 6809 that was 
availble. Lat time I checked I can only find reference to one IP core left on 
the web. It claims 40 MHz speed but does not state whether that is in an 
ASIC or FPGA. Alas I have yet to see a 6309 core. 

james