Basic adder
Half-adder (HA)
Half plus: consider only two-bit binary numbers together, without regard to low carry
c is a carry
Full adder
Taking into account the low order bits
Ci is to carry next
Ci-1 is the former carry up
Half plus: consider only two-bit binary numbers together, without regard to low carry
c is a carry
Taking into account the low order bits
Ci is to carry next
Ci-1 is the former carry up