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asm: lec10 ready for master

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shockrahwow 2018-10-03 00:29:53 -07:00
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@ -30,3 +30,20 @@ The carry bit will propagate along the operation now if we chain these together,
![fig1](../img/fig1lec10.png)
With this we can start chaining together multiple Full-adders we can start adding multiple bits at the same time since the carry now propagates along the chain.
## Ripple Adders
An N-bit adder is really just made up of Full adders chained together.
Each adder is chained to the next by the carry-out line which then acts as the next adder's carry-in line.
If we have say a 4-bit ripple adder, then each bit in the bit strings will go to a different adder.
For now the initial carry in bit will be fed a 0 everytime.
![fig2](../img/fig2lec10.png)
Here we see that our 4-bit input A & B have the values `1111` & `0000` respectively.
The 0th bit goes to Adder0, the 1th goes to Adder1, and so on.
You should have also noticed that each one also takes a carry-in, which for now is 0 but it does mean we have to let the comutation happen one adder at a time.
None of the sequential adders can do anything if the previous have done anything yet either.
At the end of it all we get some bit results, and a carry-out.
We can then simply reassemble the results back into one bit-string to assemble our final result.