[Coco] CoCo gcc project

[jdaggett at gate.net]

Neil:

My thoughts on CORDIC approach is to do the algorithms in FPGA 
and stick the chip off as a coprosessor. One can tap off the 28MHz 
clock of the Gimme chip and buffer it to provide the clock to the 
FPGA. Inside a Spartan II/IIe part you can then double that 
frequency and run the coprocessor at 56MHz. If it takes the Cordic 
processor 21 cycles to generate the sine of an angle, that will be 
about 375 nS. 

There are a few cordic cores for FPGA that are open and free to 
use on the internet. Just need to write and add more functions.

james


On 2 Nov 2003 at 12:03, Neil Morrison wrote:

> 
> If you really want to do math, you might want to look at CORDIC
> functions. They are fast, accurate, and can even do integer trig. A
> search of the web should bring up many references (Google found about
> 11,500). HP use(d) these in their pocket calculators to great effect.
> I have to admit they are weird to understand and implement, however I
> did manage to do it once, long ago.
> 
> Neil
> 
> 
> ----- Original Message ----- 
> From: "John Donaldson" <jadonaldson at charter.net>
> 
> 
> >   The fastest divide is a shift command. IIRC, one way does
> multiply by
> > 2 the other does divide
> > by 2.
> 
> 
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