TE
TechEcho
Home24h TopNewestBestAskShowJobs
GitHubTwitter
Home

TechEcho

A tech news platform built with Next.js, providing global tech news and discussions.

GitHubTwitter

Home

HomeNewestBestAskShowJobs

Resources

HackerNews APIOriginal HackerNewsNext.js

© 2025 TechEcho. All rights reserved.

Reverse-engineering the carry-lookahead circuit in the Intel 8008 processor

9 pointsby parsecsover 4 years ago

2 comments

ncmncmover 4 years ago
&gt;<i>According to 8008 designer Hal Feeney, &quot;We built the carry look-ahead logic because we needed the speed as far as the processor is concerned. So carry look ahead seemed like something we could integrate and have fairly low real estate overhead and, as you see, the whole carry look ahead is just a very small portion of the chip.&quot;</i><p>This is a very strange remark. Setting aside whether Feeney actually did design it, that look-ahead carry takes up a huge area of the chip -- almost as much as the whole rest of the ALU.<p>If they had cared about speed, they would not have shoehorned it into 18 pins.<p>According to Federico Faggin (Italian: &quot;Fah-jeen&quot;), Intel considered itself a memory company, and the 8008 project a waste of attention. They weren&#x27;t about to set up 40-pin infrastructure for a nothing part like that when no memory chip would ever need 40 pins.
kensover 4 years ago
Author here for your 8008 questions and comments!