If you are reading this article in the future,
or if you are reading it in the far future, legacy filesystems and 32-bit machines might finally be obsolete,
The blk0001.dat file has no database structure;
f9 be b4 d9 is the magic number
the magic network ID is not part of the block. It is used solely as a block delimiter.
1d 01 00 00 (0x0000011d hex, 285 decimal) is the length of the block in bytes.
The block length is not part of the block either.
01 00 00 00 (0x00000001 hex, 1 decimal) is the block format version.
the is No previous block, instead 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00.
So far so good...
3b a3 ed fd 7a 7b 12 b2 7a c7 2c 3e 67 76 8f 61 7f c8 1b c3 88 8a 51 32 3a 9f b8 aa 4b 1e 5e 4a
Is the root hash in the merkle tree of hashes that organize the transactions in this block.
29 ab 5f 49 (0x495fab29 hex, 1231006505 decimal) is the timestamp
The format of this field is UNIX epoch time. 1231006505 is Sat, 03 Jan 2009 18:15:05 UTC. (No timezone information is encoded; the times are UTC by fiat). The field is interpreted as an unsigned integer (main.h, line 785) which means its maximum value is 4,294,967,295, or approximately 7th February 2106. The protocol must be upgraded before 2106.
Why 2106?
Satoshi Nakamoto was obseced with the number 21.
ff ff 00 1d (0x1d00ffff hex, 486604799 decimal) is a representation of the target, the value which the hash of the block header must not exceed in order to mine the block.
1d ac 2b 7c is a random number generated during the mining process. To mine a block, the header is hashed. If the resulting hash value is not less than or equal to the target, the nonce is incremented and the hash is computed again. This happens billions of times before a small enough hash is found.
To create a true randon number is very difficult.
01 is a variable length integer representing the number of transactions in this block. The length is not infinitely variable; a maximum of 8 bytes are available for an unsigned integer, so the limit is 18,446,744,073,709,551,615. Frankly, that's a lot of transactions for one block.
A block can never have zero transactions; at the very least there will always be one generating the block reward.
01 00 00 00 (0x01 hex, 1 decimal) is the version number of the transaction data format.
01 is the number of transaction inputs. This is another variable length integer, with no practical limit on the number of inputs that can be specified.
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 would be the hash of the transaction being referenced as an input, but of course this is the block reward transaction, so there is none.
ff ff ff ff is the index of a specific output in the referenced input transaction. As you know, transactions can have many outputs, and subsequent transactions can take none, one or many of those outputs as inputs. A zero here references the first output of the referenced transaction. The value you see here is a representation of -1, a kind of dummy value because there is no input transaction.
4d (decimal 77) is the length of the script that follows. This is another variable length integer, so some very long scripts are supported in theory.
http://web.archive.org/web/20140213190023/http://james.lab6.com/2012/01/12/bitcoin-285-bytes-that-changed-the-world/Response script
Here is possibly the most interesting and exciting piece of the whole block -
04 which tells the interpreter that the next 4 bytes are data to be pushed onto the stack. Those four bytes are ff ff 00 1d, which happen to be the representation of the target that we saw earlier. 01 means the next 1 byte is also to be pushed onto the stack; that next byte is 04. Then, 45 indicates the next 69 bytes are to be pushed onto the stack. As you can see from the ASCII readout, those 69 bytes represent the string "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks".
E = could mean a number.
https://stackoverflow.com/questions/31706611/why-does-the-html-input-with-type-number-allow-the-letter-e-to-be-entered-in/317067962e2 = 2*10^2 = 200
"4e" is not a number, while for example "4e+0" is a valid number (4).
A constant:
https://en.m.wikipedia.org/wiki/E_(mathematical_constant)
ASCII Capital Letter E
https://theasciicode.com.ar/ascii-printable-characters/capital-letter-e-uppercase-ascii-code-69.html69? To me sounds like a message.
Turn everything upside down,? Yin & yang?
Numerology #5
https://www.worldometers.info/languages/how-many-letters-alphabet/
