- Zeta Leonis (ζ Leonis, abbreviated Zeta Leo, ζ Leo), also named Adhafera /ædəˈfɪərə/, is a third-magnitude star in the constellation of Leo, the lion. It forms the second star (after Gamma Leonis) in the blade of the sickle, which is an asterism formed from the head of Leo.
- Reverse-engineering a carry-lookahead adder in the Pentium (righto.com)
Addition is harder than you’d expect, at least for a computer. Computers use multiple types of adder circuits with different tradeoffs of size versus speed. In this article, I reverse-engineer an 8-bit adder in the Pentium’s floating point unit. This adder turns out to be a carry-lookahead adder, in particular, a type known as “Kogge-Stone.“1 In this article, I’ll explain how a carry-lookahead adder works and I’ll show how the Pentium implemented it. Warning: lots of Boolean logic ahead.