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> Why are pins counter-intuitively numbered in a rotating fashion rather than by columns as one would expect for a rectangular package? I am not sure why this

> Why are pins counter-intuitively numbered in a rotating fashion rather than by columns as one would expect for a rectangular package? I am not sure why this is counter intuitive, on a 8 pin package, it makes sense to keep pin 5 close to pin 4 to simplify the layout of the wires, and in general, it makes sense to keep consecutive pins close to one another. This applies to vacuum tubes as well.

thedufer 6y ago
Is there something particularly five-y about pin 5? Surely if you called it 8 nothing else would change. No one is suggesting redesigning the whole thing. Just move a few labels.
- krapht 6y ago
  When I look at pin 5 on a schematic, it makes it easier to find on a PCB if it is physically close to pin 4 and 6. This is true in programming too. Spatially close data should be stored in memory adjacent to each other.
  - thedufer 6y ago
    I am definitely open to the idea that the current labeling is actually more intuitive, but note that this is not at all the argument I replied to.
- bnegreve 6y ago
  Yes, consecutive pins are often related in some way. Let say pin 3,4,5 and 6 belong to the same port, and must be connected to a connector on the other side of the PCB. If pins were numbered by columns, you would have to connect two tracks to one end of the chip and two other tracks to the other end of the chip. Once you've done that, routing the remaining tracks is basically impossible on a single PCB layer.
  - bnegreve 6y ago
    In other words, the standard numbering has the nice property that two pins with a consecutive id number are always relatively close to eachother (whatever the package).
  - thedufer 6y ago
    > If pins were numbered by columns, you would have to connect two tracks to one end of the chip and two other tracks to the other end of the chip. You have missed my point entirely. All you have to do is re-label them. There is absolutely no re-wiring or re-routing implied by changing the pin numbers.
    - bnegreve 6y ago
      No I haven't, but I've failed to convince you, it seems. It does make a difference because the chip designer doesn't know or doesn't care how the chip is going to be packaged and where the pins are going to be placed on the package. With the standard numbering, two consecutive pins are always placed next to eachother no matter the package, and the chip designer can use this information to optimize the placement of related pins. This is not true with the alternative numbering "by column", where pin 4 and 5 are close on most packages, but far away on a DIP 8 package.

thedufer 6y ago

Is there something particularly five-y about pin 5? Surely if you called it 8 nothing else would change. No one is suggesting redesigning the whole thing. Just move a few labels.

krapht 6y ago
When I look at pin 5 on a schematic, it makes it easier to find on a PCB if it is physically close to pin 4 and 6. This is true in programming too. Spatially close data should be stored in memory adjacent to each other.
- thedufer 6y ago
  I am definitely open to the idea that the current labeling is actually more intuitive, but note that this is not at all the argument I replied to.
bnegreve 6y ago
Yes, consecutive pins are often related in some way. Let say pin 3,4,5 and 6 belong to the same port, and must be connected to a connector on the other side of the PCB. If pins were numbered by columns, you would have to connect two tracks to one end of the chip and two other tracks to the other end of the chip. Once you've done that, routing the remaining tracks is basically impossible on a single PCB layer.
- bnegreve 6y ago
  In other words, the standard numbering has the nice property that two pins with a consecutive id number are always relatively close to eachother (whatever the package).
- thedufer 6y ago
  > If pins were numbered by columns, you would have to connect two tracks to one end of the chip and two other tracks to the other end of the chip. You have missed my point entirely. All you have to do is re-label them. There is absolutely no re-wiring or re-routing implied by changing the pin numbers.
  - bnegreve 6y ago
    No I haven't, but I've failed to convince you, it seems. It does make a difference because the chip designer doesn't know or doesn't care how the chip is going to be packaged and where the pins are going to be placed on the package. With the standard numbering, two consecutive pins are always placed next to eachother no matter the package, and the chip designer can use this information to optimize the placement of related pins. This is not true with the alternative numbering "by column", where pin 4 and 5 are close on most packages, but far away on a DIP 8 package.