The network difficulty can not go below below a minimum level (Described as "1" these days... I.e. "the minimum", all normal difficulty numbers are expressed as multiples of this minimum value), so due to lack of sufficient hashpower the network under-produced during its first year or so.
I see. I was actually going by Blockchain.info's charts which shows the difficulty stayed at 1 during all of 2009 and also reports that Satoshi mined pretty much consistently throughout the year using multiple machines.
What was the reason for enforcing a minimum difficulty? If the network hashrate is too low and the previous blocks took too much time to generate at the prior difficulty, wouldn't it be better to change the protocol so that the difficulty is retargeted to a value under 1?
The difficulty must not be too low or an attacker may rewrite the chain very easily.
The slow period in 2009 also suggests that Satoshi did not try to maximize his bitcoin holding in the early day. He was mining only because he wanted to keep the system alive. There were only 4 blocks on 18/07/2009, while that should be 144 in the normal case
Just 1 year later, on 13/07/2010, we had 692 blocks. And that cycle is the only one with 4x jump in difficulty
