Binary Negative Numbers - Step-by-Step - Signed Magnitude, One's Complement, Two's Complement
00:00 3 Systems
00:25 Unsigned vs Signed Values
02:48 Signed Magnitude System
12:16 One's Complement System
18:46 Two's Complement System (Modern System)
These are historically the most common ways of writing negative numbers using binary. It's important to highlight that we only 'care' if there are negative numbers, if we know that the data contains signed numbers. It's all based on the context of the data, and the type of data we are reading. The memory cells that contain the data don't know or care what each byte contains, or how it combines with other bytes. They are simply bytes -- 8 bits -- and it's up to us (the reader) to interpret it based on whatever system was used to write it.