Arduino IDE Programmer Confusion

Hi all. I'm just starting out with the Arduino, and am confused about two of the programmer options under "Tools", "Programmer".

Can someone please explain to me the difference between "ArduinoISP" and "Arduino as ISP"?

ie Under what circumstances is each used?

Thanks in advance, Steve

Edit: Also, when uploading a sketch to a UNO board using the "Upload" button, which programmer needs to be selected? It's not mentioned at all in "Getting Started with Arduino on Windows". https://www.arduino.cc/en/Guide/Windows

There is an example sketch you can run on an Arduino, and it is (incorrectly and confusingly) named ArduinoISP. It appears in the menu File, Examples, ArduinoISP. When you upload this sketch to an Arduino, the Arduino becomes an ISP programmer. To use the programmer you would go on the Tools, Programmer menu and select "Arduino as ISP"

In the Tools, Programmer menu is another selection called ArduinoISP. This is the programmer you select when you have purchased an ArduinoISP device to use as a programmer. It is a retired or discontinued device but you can still find them from various sellers. https://store.arduino.cc/product/A000092

dmjlambert: There is an example sketch you can run on an Arduino, and it is (incorrectly and confusingly) named ArduinoISP. It appears in the menu File, Examples, ArduinoISP. When you upload this sketch to an Arduino, the Arduino becomes an ISP programmer. To use the programmer you would go on the Tools, Programmer menu and select "Arduino as ISP"

In the Tools, Programmer menu is another selection called ArduinoISP. This is the programmer you select when you have purchased an ArduinoISP device to use as a programmer. It is a retired or discontinued device but you can still find them from various sellers. https://store.arduino.cc/product/A000092

Thank you very much, dmjlambert, that clears up my confusion on that issue. I'll leave the programmer selection set on "Arduino as ISP" and pretend that the other "ArduinoISP" programmer option doesn't exist. :) I've already figured out how to burn the bootloader to a new chip and designed a small PCB to do so. (Haven't etched the board yet.)

I'm confused about one other small issue. The instructions I read said to fit a ceramic resonator on the target PCB, connected to pins 9, 10 and ground, yet I just saw another set of instructions on the ADAfruit site that don't mention a resonator, but instead said to connect pin 9 on the target chip to pin 9 on the programming Arduino. Do you know which is correct, or are both methods acceptable? (I might need to change my PCB layout.)

Edit: I should add at this point that I haven't actually got my UNO yet - still waiting for it to arrive.

Adafruit has a version of the Arduino as ISP sketch which produces a clock signal on pin 9 of the programmer Arduino. This is useful in case you are programming a chip which is not connected to a crystal or resonator but the fuses on it are set so it requires an external oscillator. If you are programming a chip which is installed in a supporting circuit which includes a crystal or resonator, then you would not need to use that extra feature of the Arduino as ISP sketch. Nick Gammon’s bootloader sketch also has that same feature of providing a clock signal on pin 9.

It is just a handy thing in case you are trying to do something tricky. For example, you can pull a chip from a working circuit which has a crystal, and use it for another purpose where you want to reset the fuses and use the internal oscillator. Instead of saying “oh darn it” when you find out you can’t program the lone chip when it is out of its support circuit and returning it to the original board just long enough to reset the fuses, you can just hook up pin 9 to the crystal-in pin.

dmjlambert: Adafruit has a version of the Arduino as ISP sketch which produces a clock signal on pin 9 of the programmer Arduino. This is useful in case you are programming a chip which is not connected to a crystal or resonator but the fuses on it are set so it requires an external oscillator. If you are programming a chip which is installed in a supporting circuit which includes a crystal or resonator, then you would not need to use that extra feature of the Arduino as ISP sketch. Nick Gammon's bootloader sketch also has that same feature of providing a clock signal on pin 9.

It is just a handy thing in case you are trying to do something tricky. For example, you can pull a chip from a working circuit which has a crystal, and use it for another purpose where you want to reset the fuses and use the internal oscillator. Instead of saying "oh darn it" when you find out you can't program the lone chip when it is out of its support circuit and returning it to the original board just long enough to reset the fuses, you can just hook up pin 9 to the crystal-in pin.

Thanks once again. Much appreciated. I'll leave my PCB layout the way it is then, and fit a ceramic resonator. Now if only my Arduino would hurry up and get here, I'm good-to-go.