-snip- I find it hard to believe that someone was mining Bitcoin that early on in its existence but is struggling to understand how to work the private keys and can't point out his address. But exceptions do occur.
It was too easy for newbies actually, just have to download "
Bitcoin" which was exclusively for Windows, then tick "
Option->Generate Coins" and pooof... it's mining.
If his "
friend" is honest that it's not bought, then I think they accidentally made a fork back then and mined a block in their own blockchain.
How do it with new computer, which files do I need to move to new computer?
Copy the wallet.dat from bitcoin's data directory (
en.bitcoin.it/wiki/Data_directory#Default_Location)
Paste it to the new PC's "
wallets" folder inside bitcoin data directory, rename the wallet file or put it inside a folder with your preferred wallet name
then Open Bitcoin Core and load using the menu: "
File->Open Wallet".
You don't have to put it to a fully synced Bitcoin Core since it's only @4111 which is a few (
nearly)empty blocks away from the genesis block.
After getting past that height/block timestamp, you can immediately see in the transactions tab if your generated bitcoin is verified (
with check) or invalid (
with questionmark)
Spoiler:
hover-over your mouse pointer