i cant understand somt part of this circuit..

[transgalactic]

**broken link removed**

its supposed to get to number and out their sum in base 5

for example 3+4=1 2

the first part of the circuit is the sum of the input number

i cant understand the next part:

what is the logic behind this gate system in between
and what is the role of the HA adders that comes after that


????

 

[tkbits]

Supposedly, all the logic that follows the basic adder will conditionally adjust the output for base 5.

With decimal adjust circuits, one adds 6 to the sum digit when it is greater than 9, but add nothing if the sum is not. That will adjust the sum digit, and force a carry out for sums > 9.

Work it out in hex or binary to see that the above method works.

The base 5 circuit ought to be doing a similar thing, but with a different adjustment value.