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Inside the 74181 ALU chip: die photos and reverse engineering

Posted on Wednesday, January 11th, 2017 in reversed by DP

pics-die-layout-600

A detailed die photos and reverse engineering 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 popular chip in the 1970s used to perform calculations in the arithmetic-logic unit (ALU) of minicomputers. It is a moderately complex chip containing about 67 gates and 170 transistors3, implemented using fast and popular TTL (transistor-transistor logic) circuitry.

More details at Ken Shirriff’s blog.

This entry was posted on Wednesday, January 11th, 2017 at 3:17 pm and is filed under reversed. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.

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  • Drone: So these go for around $330 USD and NO published calibration procedure online or otherwise? Given what's inside - I don't think I'll be considering...
  • Pekka Akselin: This is ridiculous!? :-) We are back at 256(!) byte EPROMs that needed multiple, a handful, of voltages to run! :-(
  • KH: Let's try a back-of-envelope calc balancing energies. From MCP1700 datasheet, there are graphs for a 200mA load step. Estimate the energy shortfall as 12uJ. Say...
  • Daniel: It's been a week and my comment is still awaiting moderation. Apparently the CIA doesn't want their involvement known?
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