understanding timestamp from blockexplorer.com What is the timestamp used for the blocks on blockexplorer.com 
For example block 233969 has: 
Time: 2013-04-30 23:27:36 

is this time converted to 32bit hex for hash calculation, if so how ?
In the network protocol, times are represented as Unix timestamps stored as unsigned 32-bit integers.


  is this time converted to 32bit hex for hash calculation, if so how ?


Bitcoin uses a binary protocol. Nothing is hex. When viewing the binary data, your tools may display the data in hex, but you can't directly use these hex characters for hashing, etc.