Glenn,

If you want to "build out" a bus you can. I would consider the advise within the previous posts.

Peter's suggestion is not difficult to do and has some advantage if you are interfacing to slow devices.

The result of "building out" your own bus, (that i can see) is that you result in a 20 pin processor driving your bus with 15 lines. With these few lines interfacing multiple peripherals will be where the "trouble" will emerge.

You might consider using some "serial" parts to augment your '2051/'4051. These devices allow a great deal of expansion and still retains a small footprint.

regards,
p