This adder is made from 5 of the little adders in the last page. It can add a pair of numbers each between 0 and 31 and produce a result between 0 and 62
If you stare at that long enough, you might start to see the paterns of how the logic works. You can go back to the simple adder to see what is inside each box. Remember: It's all done with NANDs!
The 2 bit to 4 line active low decoder puts things in order.
It should be easy to see how we could add more adders to build a circuit that would add 6, 7, 8 or more bit numbers together. Most computers today can add 32 bit numbers in a single operation; they have 32 bit adders. A 32 bit number can have a value between 0 and 4,294,967,296 (about 4 billion).
See also:
| file: /Techref/logic/add5.htm, 1KB, , updated: 2010/5/25 09:34, local time: 2010/9/2 21:38,
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