What explains the counter-intuitive numbering of chip pins?
- Thread starter cyrano
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john12ax7
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I never knew either, pretty cool info.
> I had no idea chip pin numbering came from tubes:
Probably, like railroad rail gauge, comes from the width of a Roman horse's ass. But...
> Octal base vacuum tube numbering (7AK7)
Integrated circuits seem to have inherited this numbering scheme from vacuum tubes.
SEEMS? Doesn't sound real researched or conclusive.
The writer seems to have missed a major step in packaging history, the 8-pin TO-5. IC pins were in a circle. Only later did the cheaper DIP package come out. For a while we were bending TO5 pins to fit DIP sockets and even DIP pins to fit TO5 holes (did not work well).
Probably, like railroad rail gauge, comes from the width of a Roman horse's ass. But...
> Octal base vacuum tube numbering (7AK7)
Integrated circuits seem to have inherited this numbering scheme from vacuum tubes.
SEEMS? Doesn't sound real researched or conclusive.
The writer seems to have missed a major step in packaging history, the 8-pin TO-5. IC pins were in a circle. Only later did the cheaper DIP package come out. For a while we were bending TO5 pins to fit DIP sockets and even DIP pins to fit TO5 holes (did not work well).
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This question is not worth the electrons it has disturbed.
Tube pin-out was usually seen from the bottom, because that's how you wired the sockets. Numbering was CW bottom-view. This continued with semiconductors in round metallic package (TO5 and TO3). http://ronja.twibright.com/datasheets/metal_cans.pdf
When PCB's took over hand-wiring, it made sense to represent components in top view, where numbering appeared in CCW rotation.
Tube pin-out was usually seen from the bottom, because that's how you wired the sockets. Numbering was CW bottom-view. This continued with semiconductors in round metallic package (TO5 and TO3). http://ronja.twibright.com/datasheets/metal_cans.pdf
When PCB's took over hand-wiring, it made sense to represent components in top view, where numbering appeared in CCW rotation.
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