3 ms·

I studied as an EE. I struggled as a freshman to figure out how flip-flops work (building blocks of registers) when it dawned on me while in the shower that the

I studied as an EE. I struggled as a freshman to figure out how flip-flops work (building blocks of registers) when it dawned on me while in the shower that they only work due to propagation delay. What an eye openning shower that was...

acjohnson55 7y ago
I feel like some teacher failed you that this wasn't made more explicit.
- CamperBob2 7y ago
  Eh, it's a subtle point. Unequal propagation delays are how a bistable F-F finds its initial state, but once static operation is established, only the maximum toggle rate depends on propagation delay. And astable flip-flops usually have separate, explicit timing elements rather than relying on gate charge or whatever.
  - acjohnson55 7y ago
    I think you might be talking about deeper elements of design than the basic fact of delayed feedback through logic gates implementing memory.
  - hermitdev 7y ago
    I agree. I actually think my instructors were excellent. I had a mental block that needed clearing. My EE instructors went out of their way to spend as much time in office hours as needed to students that needed it. I remember spending several hours in one instructors office trying to figure out where I was going wrong. She was also confused because all of my intermediate work was correct, but I always came up with the wrong answer. Short of it was that I was entering numbers in as reciprocals of what they should have been. E.g. I was entering 1000 in my calculator instead of 1/1000. Took 2 sets of eyes and a couple of hours to spot the problem. Went from barely getting a C at midterms to not losing a point the rest of the semester. Finished with a solid B amd the next semester was perfect. Only ended up there because of my instructor's help and accessibility.
    - fatnoah 7y ago
      > I remember spending several hours in one instructors office trying to figure out where I was going wrong. She was also confused because all of my intermediate work was correct, but I always came up with the wrong answer In grad school, I was a TA for some undergrad EE courses. We (the TAs) and professor corrected tests together and whenever we encountered a wrong answer, we'd always replicate the student's work to find where things went wrong so we could a) point it out and b) give partial credit whenever possible. For a class of 120 students, it took four of us two days to get through all of the tests.

acjohnson55 7y ago

I feel like some teacher failed you that this wasn't made more explicit.

CamperBob2 7y ago
Eh, it's a subtle point. Unequal propagation delays are how a bistable F-F finds its initial state, but once static operation is established, only the maximum toggle rate depends on propagation delay. And astable flip-flops usually have separate, explicit timing elements rather than relying on gate charge or whatever.
- acjohnson55 7y ago
  I think you might be talking about deeper elements of design than the basic fact of delayed feedback through logic gates implementing memory.
- hermitdev 7y ago
  I agree. I actually think my instructors were excellent. I had a mental block that needed clearing. My EE instructors went out of their way to spend as much time in office hours as needed to students that needed it. I remember spending several hours in one instructors office trying to figure out where I was going wrong. She was also confused because all of my intermediate work was correct, but I always came up with the wrong answer. Short of it was that I was entering numbers in as reciprocals of what they should have been. E.g. I was entering 1000 in my calculator instead of 1/1000. Took 2 sets of eyes and a couple of hours to spot the problem. Went from barely getting a C at midterms to not losing a point the rest of the semester. Finished with a solid B amd the next semester was perfect. Only ended up there because of my instructor's help and accessibility.
  - fatnoah 7y ago
    > I remember spending several hours in one instructors office trying to figure out where I was going wrong. She was also confused because all of my intermediate work was correct, but I always came up with the wrong answer In grad school, I was a TA for some undergrad EE courses. We (the TAs) and professor corrected tests together and whenever we encountered a wrong answer, we'd always replicate the student's work to find where things went wrong so we could a) point it out and b) give partial credit whenever possible. For a class of 120 students, it took four of us two days to get through all of the tests.