If I download optiboot burn a nano optiboot bootloader into a 328p on one pc, can I upload a sketch using another pc that does not have optiboot installed into the Hardware folder? In not clear if the optiboot bootloader will work on a freshly installed IDE on another pc.
When the ATmega328P on the Nano has the optiboot bootloader you can just treat it as an Arduino UNO. You won't be able to use A6 and A7. To get those back you need to add 'boards.txt' to your Arduino/hardware/ folder:
[quote]
##############################################################
nano328o.name="Arduino Nano w/ ATmega328 & optiboot"
nano328o.upload.protocol=arduino
nano328o.upload.maximum_size=32256
nano328o.upload.speed=115200
nano328o.bootloader.low_fuses=0xff
nano328o.bootloader.high_fuses=0xde
nano328o.bootloader.extended_fuses=0x05
nano328o.bootloader.path=optiboot
nano328o.bootloader.file=optiboot_atmega328.hex
nano328o.bootloader.unlock_bits=0x3F
nano328o.bootloader.lock_bits=0x0F
nano328o.build.mcu=atmega328p
nano328o.build.f_cpu=16000000L
nano328o.build.core=arduino
nano328o.build.variant=eightanaloginputs
Since your hardware folder is in your sketch folder it will still be usable when you update the Arduino app. If you move to another machine with a fresh Arduino install you either select "Arduino UNO" and loose the two additional analog inputs or you copy the boards.txt entry and use "Arduino Nano w/ ATmega328 & optiboot".
To clarify, the IDE does not need to have Optiboot present in the file system to talk to Arduinos. It is only needed if you want to burn bootloader.
However, yo do need to have the proper boards.txt entries to select the proper Tools->Board type, so that it will communicate at the proper serial baud rate.
So for a fresh IDE install you should be able to talk to any Arduino as long as you have the proper Board definition to select from.
Perfect. Thanks for the replies.
Mike