ASCII Character Code

The computer uses ch as a integer index into a pre-existing table
the computer screen is made up of a thousand little dots called pixels. theyre in a rectangular grid like a table.a

ascii code example
There are several tables that describe what to draw
- fonts describe how to draw them
ASCII (american standard code for information) describes what should be drawn for Roman (english like) alphabets
e.g.,
- A 1000001 (65)
- B 1100001 (97)
- 9 0111001 (57)
There are only a few letter numbers and punctuation marks. The remaining ASCII code are non-printing and have other meaning (line feed, for feed, tab etcc)
ASCII characters are stored using 7-bits
- so there are 128 (2^7) possible characters
- stored as a byte with the 8th bit set to zero
- For sorting purposes characters are compared on their numeric value (called the collating sequence)
- 'A' is before 'Z' but 'a' is after 'Z'!