Here's the algorithm I awoke with:

All you have to do is take the last value, shift it once left and XOR it with the current value. If bit 1 (zero relative) is 1 then its one direction if its 0 its the other. This occurs because the xor result is 1 or 4, its one direction, if its 2 or 7 its the other.

Using the last code as an example:

.dowhat:
. mov a,r7 ;get last dibit
. rl a
. xrl a,r6 ;combine with current
. jb acc.1,doup ;jig dial up
.dodn: ;else dial down
...
.doup:
...

You'll have to screen the no change and skip conditions or figure out their reslts.

That is a cool algorithm!

Jay C. Box