vault backup: 2022-07-23 23:04:14

content/notes/04-computer-architecture.md

@@ -7,7 +7,44 @@ tags:
 
 
 - tristate buffer [slide](https://i.imgur.com/2Kb419g.png)
-- ![memory write](https://i.imgur.com/PExnbFm.png)
+- ![memory write](https://i.imgur.com/PExnbFm.png) [circuit simulator](https://tinyurl.com/2bmqovqz)
 - ![memory read](https://i.imgur.com/GZwxuaA.png)
 
+# Bus
+- data bus
+- address bus
+- control bus
 
+- conmmunicate between parts of the computer
+- only one transmitter at a time
+- only addressed device can respond
+- 2 levels
+	- internal
+	- external
+
+# Memory
+- memory size is dependent on bus size
+	- 2n bytes for n-lines on the address bus
+		- 2^8=256B, 2^16=64KB, 2^32=4GB, 2^64=16EB
+
+- flip flops are grouped into bytes (or larger)
+	- each byte has an address
+	- to write
+		- present the address and the data
+		- tell chip to write
+	- to read
+		- present the address
+		- tell the chip to read
+		- look at the data
+
+## Static RAM (SRAM)
+- memory made from flip flops is called static RAM
+	- used mostly in CPU cache
+	- or anywhere where only a small amount is needed
+	- expensive
+
+## Dynamic RAM (DRAM)
+- made from capacitors
+- used where large amount of RAM is needed
+- slower than SRAM
+- inexpensive