[Coco] DW and 6551

[Darren A]

On Wed, Feb 11, 2015 at 8:37 AM, Joe Grubbs <jsgrubbs at hotmail.com> wrote:

> That makes sense... The faster your tx/rx speed, the buffer has to grow as
> well to be effective. So realistically, it's possible that using an old
> 6551 with high speed will have a small or perhaps insignificant impact on
> CPU load reduction versus the bit banger. Bummer.
>
>
Using a 6551 at 115 kbps will not free up the CoCo's cpu for any other
tasks.  At that speed you would still need to mask interrupts and run a
tight loop to service the 6551.  The difference between a 6551 driver and
the DW bit-banger code is that the CPU will spend much of the time spinning
its heels while waiting for the status register to indicate that its time
to transfer another byte.

- Darren