Lpc2000

>   while (1)
>   {
>     acc = acc + adder;      //update phase accumulator
>     ptr = (acc &= 0xFF);    //pointer into table
>     IOSET = sawtooth[ptr] << 8;
>     IOCLR = (~sawtooth[ptr] << 8);
>    }
>
>apart from glitches - spurs on the waveforms. I think I had the ~ in the
>wrong place.
>
>I didn't get those glitches with the AVR, using the same DAC.

Scope your output lines and compare to the glitches.  I suspect they are 
coming from the fact that not all of your lines change at the same 
time.  Going from a value of 3 to a value of 4 I would expect to see a 
sequence of 3, 7, 4 given your code.

I think there may be either a HW or a SW fix.  THE SW fix would involve 
going against the User manuals recommendations though.

Robert