UN: how to computer

content/notes/ready/how_to_computer/index.md

@@ -530,7 +530,105 @@ A Bus is useful to simplify wiring. One bit controls which input should be selec
 
 ![[bus.png]]
 
-### ASCII
+### 1 Bit of Memory
+
+There are many ways to achieve a bit of memory.
+
+#### Using Transistors and a Tick Delay
+
+The oval component is a delay. This replaces the concept of a clock, however, in an electronic circuit, the save and load states are attached to a clock.
+
+![[transistor_latch.png]]
+
+#### AND-OR Latch
+
+TODO!!!
+
+![image80](image80.png)
+
+### 8bit Register
+
+After obtaining one bit of memory, a byte of memory can be built.
+
+![[8bit_register.png]]
+
+### Binary Decoder
+
+A decoder splits two states of a bit into two separate outputs.
+
+![[decoder.png]]
+
+### 3bit Decoder
+
+![[3bit_decoder.png]]
+
+---
+
+## Remembering Data
+
+An `OR` gate could be used to store a single bit.  
+![image76](image76.png)  
+If the input `A` is changed to `1`, the `OR` gate will output `1`, and then receive it.  
+![image77](image77.png)  
+Even after the input `A` is set to `0`, the output does not change. The `OR` gate "remembers" that, at one point in the past, the `A` input was set to `1`.  
+![image78](image78.png)  
+The inverse can be done with an `AND` gate.  
+![image79](image79.png)  
+To remember either a `1` or a `0`, we can do the following:  
+  
+
+### AND-OR LATCH
+
+The input `A` sets the output to `1`, and the input `B` sets the output to `0`. This circuit is able to store a bit of information, while powered on, even after both inputs are set to `0`.  
+A slightly more advanced and intuitive version can be built as follows:  
+![image81](image81.png)  
+
+### GATED LATCH
+
+The input `A` is the value to store, and when `B` is set to `1`, the value is stored.  
+This is not the only way to store data using logic gates, but it is one of the simplest.
+
+## Registers
+
+A single bit isn't very useful, so we can use the previous circuit to create an 8bit register.  
+![image82](image82.png)
+
+## Binary Decoder
+
+Select which circuit to activate, depending on the task at hand.  
+![image83](image83.png)
+
+## RAM
+
+Registers don't scale well, however, as storing a large amount of data would require millions of wires.  
+We can organize latches in a matrix instead of a long, horizontal line.  
+![image84](image84.png)  
+To access a specific latch, binary decoders can be used.  
+![image85](image85.png)  
+This way, a single, short memory address can select any latch in the matrix.
+
+### Reading and Writing to the Matrix
+
+We can modify the latch to reduce the amount of wires needed.  
+![image86](image86.png)  
+This new latch uses the same wire for both input and output.  
+![image87](image87.png)  
+This circuit would store the same value on every latch, which isn't useful. With some modifications, however, we can use the memory address to select which latch to modify.  
+![image88](image88.png)  
+![image89](image89.png)
+
+### Storing Bytes Instead of Bits
+
+![image90](image90.png)  
+In this example, we can provide 1 byte of information, a `write` or `read` signal, and a memory address. Since we are storing a full byte, the same memory address applies for all 8, single bit circuits.  
+This configuration is more commonly known as **RAM**.  
+To make it easier to understand, we can abstract these concepts further.  
+![image91](image91.png)  
+The largest the Address Bus is, the more bits can be managed. This is why a 32bit CPU can't manage more than 4 GB of RAM.  
+![image92](image92.png)  
+This kind of RAM is Static RAM (**S**RAM), which uses many transistors, making it faster, but more expensive to produce than **D**RAM.
+
+## ASCII
 
 Binary can also be used to represent characters.