!! All information below is for Windows. If you're using another OS, let me know and I'll update the directories to the correct ones
Please also
backup your .dat files before making any changes in the blockchain data directories.
>If I did have the blockchain downloaded and I wanted to move my external hard drive (pruned/no blockchain) and plug it into another computer, could I still access the Bitcoin Core wallet? (Everything is on the external hdd including Bitcoin Core)
As long as you have the data directory files on the external disk and your Core wallet on the secondary computer is configured properly to use the data from it, yes - you could.
If you want to make use of the data from your external hard disk, all you have to do is plug in the external disk, launch the Core wallet on the secondary PC and set the external disk as your data directory.
As far as I know, you can set the data directory the following way:
- If it's the first time you're starting Bitcoin Core, upon launch a window will pop up asking where you'd like to store the blockchain data. Set that manually to the external disk instead of the default folder
- If it's not the first time you're starting the Core wallet, then you probably already have a ".config" file created. Go to the data directory folder of your Core wallet (the default is %appdata%\Roaming\), open the ".conf" file and edit the line "datadir=A:\Example\Path" to send the Core wallet to the correct path.
>If no, could I do that if I did have the blockchain downloaded onto the external hdd?
I think you just said above this question that you had the data already downloaded on the external HDD?
>And if I wanted to setup a new wallet on a new computer, could I just copy and paste the blockchain directory into the Bitcoin Core folder on the other computer?
You can either:
- Plug the external HDD with the existing blockchain data on it into another computer
- Open a Bitcoin Core wallet executable file on the computer and upon the first-start window manually select the external HDD
or
- Plug the external HDD with the existing blockchain data on it into the secondary computer
- From your external HDD, copy all the data directory files except the ".conf" file (if you have one)
- Paste the files into the directory you'd like to store them on the secondary computer (default directory is %appdata%\Roaming\)
- Plug out the external HDD and set the copied directory as the data directory by following the answer of the first question
>And then would I still need to download anything over say 50-100GB to sync that new wallet up?
As long as the files you have in the data directory are up-to-date, no. But if you're missing 50GB of data, affirmative - it'll need to download that much as it obviously needs to keep up with the network or your transaction history and account balance would otherwise not be accurate, real-time.
