vault backup: 2022-07-11 10:31:04

content/notes/01-bits-and-bytes.md

@@ -57,4 +57,26 @@ tags:
 - characters are joined together to make human readable numbers and words
 
 - `char ch` 
-- ch is a variable name
+- ch is a variable name (identifier) 
+- used to label a location in the computer's memory where a byte is stored
+- when the code is compile, the name is assigned an address, in memory. The meaning of that data depends on how a human interprets it. it might be small integer, or a character, or a color etc.
+
+## ASCII Character Code
+1. The computer uses ch as a integer index into a pre-existing table 
+2. 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](https://i.imgur.com/9uvKRVo.png)
+
+- 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 p
+