diff --git a/content/notes/01-bits-and-bytes.md b/content/notes/01-bits-and-bytes.md index 2af7c98e5..a43e48331 100644 --- a/content/notes/01-bits-and-bytes.md +++ b/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 +