diff --git a/School/Analyse/Periode 2/Week 1.md b/School/Analyse/Periode 2/Week 1.md
index dc5cb90..49e212b 100644
--- a/School/Analyse/Periode 2/Week 1.md	
+++ b/School/Analyse/Periode 2/Week 1.md	
@@ -4,4 +4,24 @@ Handles devices that allow the computer system to:
 * Communicate and interact with the outside world
 	- Screen, keyboard, printer
 
-* Store information
\ No newline at end of file
+* Store information
+
+![[io-subsystem.png]]
+
+# The Control unit
+Program stored in memory. (machine language in binary)
+
+Task of control unit is to execute programs by:
+* Fetch: from memory the next instruction
+* Decode: instruction to determine what to do
+* Execute: issuing signals to ALU, memory and IO systems.
+
+Repeats until HALT instruction.
+
+# Typical Machine Instructions
+MOV: move data from a to b
+ADD: add numbers
+SUB: subtract numbers
+JMP: transfers program control flow to the indicated instruction
+
+
diff --git a/io-subsystem.png b/io-subsystem.png
new file mode 100644
index 0000000..98a43f8
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