Comments: Logic Levels
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Although TTL and CMOS are by far the most common "level definitions", readers should be aware that there are.many others, although most of them are rare. There are even ones that use current rather than voltage to convey logic levels, but the typical hobbyist is very unlikely to encounter these.
In the "another way" (second) picture, the .5 should be a .4, I believe. (I tried to send this as "feedback," but that screen does not work on my computer. It lets me fill stuff in, but it doesn't "confirm a send." I might be blocking something such as Google. Indeed, on another screen, your system told me it needed Google Captcha. So I allowed the normally blocked Google, and the page worked. The feedback page is not telling me anything it needs is blocked.)
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Thanks for the simple diagram of the TTL and CMOS levels and ranges. Made things much more clear for me and it was a more clear explanation than I've found elsewhere.