Summary IB Computer Science Topic 2: Programming and Problem Solving Excellence

IB SL Computer Science
Quarter 1
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Notes




Unit 2: Computer organization
2.1.1 The central processing unit (CPU) and its elements
During the Processing phase of the computer, the computer will sometimes use other
information other than the inputs and new data is also sometimes saved.

The processing happens in the CPU which retrieves and saves information from the
primary memory, so everything data that the CPU uses has to go through the RAM first.

● CPU (central processing unit)
○ Key component of a computer system
○ Contains circuitry
■ Can fetch, decode, and execute program instructions from RAM

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● ALU (Arithmetic Control Unit)
○ Does arithmetic and logic calculations
○ Also referred to as a core
○ Does



● CU (Control Unit)
○ Handles the loading of new commands into the CPU
○ decodes these commands
○ Manages the sequence of executions
○ Directs the dataflow and operation of ALU
○ Contains the registers



● Registers
○ Small fast circuits that store intermediate values from calculations or
instructions inside the CPU
○ Basically the memory of the CPU
○ Memory address register (MAR)