Can I store Bitcoin on a 16 MB SD card?

[Analyticse]

i am same question interest   
if make format and delite posible make this restore walet or fix

[m4ti]

But what happens if I can't restore the vanity adress? The received Bitcoins should stay in my wallet, even if the private key of the vanity adress gets lost, or not?

[cp1]

Wallet is just a collection of keys.  You need the keys to spend the coins.  Don't worry about the wallet, just worry about the keys for your vanity addresses.  Really though don't use vanity addresses.

[m4ti]

Hmm, okay... I will delete the vanity adress. So if I copy the wallet.dat onto the sd and create some adresses later,  they will be safe too?

I don't understand, why I need to recover the adresses for SPENDING Bitcoin. Can't I just spend them with another adress (which I can create, after my PC has crashed), or is there something like a "master adress", which is used for sending Bitcoins?

[cp1]

Hmm think of it like this.

Each address is a unique account.  It has a balance, say 5 BTC.  To spend that BTC you need the key to the address.

You will have more than one address.  Each has their own balances.  Each has their own key.  If you don't have the key corresponding to a certain address you can't spend the BTC stored in that address.

Because you will have many addresses, like 10-100, you group them together in a wallet.  A wallet is just a file (like wallet.dat) that has a list of your addresses and their keys.

Because it's annoying to have to keep track of 100 addresses and 100 keys, there are programs, like electrum, that allow you to only keep track of one long master key (the seed).  Using this seed and some math that I don't understand, the program can generate millions of addresses and corresponding keys.  Because it can generate them from the seed, this allows you to have multiple addresses and keys but only one master seed to have to backup.  Of course you should also backup the wallet file (they're not all called wallet.dat -- it depends on the program you're using).

If you don't use a program like electrum you need to backup each address and its corresponding key.  If you lose the key to the address you can't spend the coins located there.  There are lots of coins that are "lost" forever because people lost the key to them.

[m4ti]

But what if I receive 5 BTC with adress "123" and 5 BTC with adress "abc"?
I can spend the sum of 10 BTC from a third adress "xyz", if all three adresses are in the same wallet. Even if I never received a single Bitcoin with adress "xyz" .....

So if I have written down the seed and backed up my wallet.dat (or how it's named) my Bitcoins are safe from getting lost by PC crash, even if I create a new adress and receive Bitcoin with it later than the PC crash? Or am I wrong?

[byt411]

But what if I receive 5 BTC with adress "123" and 5 BTC with adress "abc"?
I can spend the sum of 10 BTC from a third adress "xyz", if all three adresses are in the same wallet. Even if I never received a single Bitcoin with adress "xyz" .....

So if I have written down the seed and backed up my wallet.dat (or how it's named) my Bitcoins are safe from getting lost by PC crash, even if I create a new adress and receive Bitcoin with it later than the PC crash? Or am I wrong?

You cannot send BTC from xyz if your funds are in 123 and abc. Also, your wallet is safe, unless someone gets your private key and spends your bitcoins.

[cp1]

But what if I receive 5 BTC with adress "123" and 5 BTC with adress "abc"?
I can spend the sum of 10 BTC from a third adress "xyz", if all three adresses are in the same wallet. Even if I never received a single Bitcoin with adress "xyz" .....

If you have $1000 in checking account abc and $0 in checking account xyz, try to write a check for $1000 from xyz and see how that goes.

[m4ti]

Ah, finally I understood 

But another last question:

In Multibit I could spend my complete wallet balance at once. At first It sent the BTC received with other adresses to the first adress and then to the receiving adress. Everything full automatic. Is this in Electrum automatic too, or do I have to do this manually?
e.g. 1 BTC is on adress 123, 1.5 BTC are on abc and 0.5 on xyz - now I could send all 3 BTC at once. It sent 1.5 + 0.5 to adress 123 and then all 3 to the adress, receiving it. Everything in one transaction.

[byt411]

Ah, finally I understood 

But another last question:

In Multibit I could spend my complete wallet balance at once. At first It sent the BTC received with other adresses to the first adress and then to the receiving adress. Everything full automatic. Is this in Electrum automatic too, or do I have to do this manually?
e.g. 1 BTC is on adress 123, 1.5 BTC are on abc and 0.5 on xyz - now I could send all 3 BTC at once. It sent 1.5 + 0.5 to adress 123 and then all 3 to the adress, receiving it. Everything in one transaction.

Yes. That happens with almost all wallets, and no hassle required.

[cp1]

That's why we use wallets.  Because they have info on all of our addresses (accounts) and all the corresponding keys, we just tell it to send our desired amount and it can send from multiple addresses that add up to our desired amount.