Four groups of 32, each group differing in only one bit position.
Why were the first 32 devoted to "control" codes? Because ASCII appeared in the days of mechanical paper teletype interfaces to computers and so there was a need for codes to control the teletype. Additionally the intent was to use other of the control codes for "control" (i.e., use of XON (control-q) and XOFF (control-s) for flow control).
> Why did they have to start the whole "newline vs carriage return" thing,
Because when you have a mechanical paper teletype printer as your interface to the computer, the teletype printer needs to be told to do two things:
1) return the print carriage to the left margin
2) roll the paper up one line
Having the ability to do both independently (for a paper printer) allows for simulating some otherwise impossible effects (i.e., bold face).
> Why is it 7-bit and not 8-bit?
To allow bit 8 to be used for a parity bit for data transmission purposes.
> Why is there no pilcrow, paragraph symbol, dagger and double dagger in it?
> Why no symbols for not equals, subset, intersection, union, (no) element of, AND, OR in it?
Likely because, after choosing to make a 7-bit code (to allow bit 8 to be parity), there is only so much room left in only 128 slots.
Comments
> Why did they make most the first 32 symbols useless codes instead of also symbols?
Why the first 32. Symmetry. Look at the table here: https://commons.wikimedia.org/wiki/File:ASCII_Code_Chart-Qui...
Four groups of 32, each group differing in only one bit position.
Why were the first 32 devoted to "control" codes? Because ASCII appeared in the days of mechanical paper teletype interfaces to computers and so there was a need for codes to control the teletype. Additionally the intent was to use other of the control codes for "control" (i.e., use of XON (control-q) and XOFF (control-s) for flow control).
> Why did they have to start the whole "newline vs carriage return" thing,
Because when you have a mechanical paper teletype printer as your interface to the computer, the teletype printer needs to be told to do two things:
1) return the print carriage to the left margin
2) roll the paper up one line
Having the ability to do both independently (for a paper printer) allows for simulating some otherwise impossible effects (i.e., bold face).
> Why is it 7-bit and not 8-bit?
To allow bit 8 to be used for a parity bit for data transmission purposes.
> Why is there no pilcrow, paragraph symbol, dagger and double dagger in it?
> Why no symbols for not equals, subset, intersection, union, (no) element of, AND, OR in it?
Likely because, after choosing to make a 7-bit code (to allow bit 8 to be parity), there is only so much room left in only 128 slots.
> Four groups of 32, each group differing in only one bit position.
That's impossible. If you have four groups, they have to differ in at least TWO bit positions.
> .. allows for simulating some otherwise impossible effects (i.e., bold face).
A better example is underlining.