~snip~
But I can put all of the data of a floppy 1,44mb in a block?
However we can not open or use this data?
Yes, you can upload and download data from the Blockchain.
Here is for example how to grab the bitcoin whitepaper from the blockchain:
seq 0 947 | (while read -r n; do bitcoin-cli gettxout 54e48e5f5c656b26c3bca14a8c95aa583d07ebe84dde3b7dd4a78f4e4186e713 $n | jq -r '.scriptPubKey.asm' | awk '{ print $2 $3 $4 }'; done) | tr -d '\n' | cut -c 17-368600 | xxd -r -p > bitcoin.pdf
You end up with a bitcoin.pdf file in your computer, grabbed from the blockchain.