Inside the 74181 ALU chip: die photos and reverse engineering

A detailed die photos and reverse engineeringĀ of the 74181 ALU chip by Ken Shirriff: What’s inside a TTL chip? To find out, I opened up a 74181 ALU chip, took high-resolution die photos, and reverse-engineered the chip.1 Inside I found several types of gates, implemented with interesting circuitry and unusual transistors. The 74181 was a […]

Help your robot do its Math homework

Ladvien over at LetsMakeRobots writes, “Excellent article on clock-cycle costs of math functions for uCs and processors–as they relate to programming robots.” This first point is the single most important one to remember. Integer math is almost always faster than floating point, even on processors that have floating point math units. A whole lot faster […]