Computer science is the study of algorithm

Modern computers are built using Von Neumann machine architecture.

Von Neumann machine have 3 aspects:

1. Architecture: I/O + Memory + CPU (CU: Control Unit + ALU: Arithmetic & Logic Unit)
   1. Those components are connected to the BUS
2. Stored Programs: All programs and data are in stored as binary information in the memory
3. Sequential Execution: The CPU will do 1 thing at a time. In 1 cycle the CPU will do one and one thing only.
   1. This is also known as Fetch Decode Execute
      1. Memory (is binary information) → fetched → CU → Decoded → ALU → Execute (the task).
      2. Decode and Execute are done by the same computer chip: the CPU

Computer memory is organized as a hierarchy. At the bottom, there is the hard drive. At the top level there is the CPU.

Because hard drives are slow, when a software is loaded, the software gets loaded in the Random Access Memory (RAM).

The RAM is still not fast enough for the CPU, so the instructions are actually executed in the Cache memory. HD: Probably TB in size RAM: Probably GB in size Cache: Probably KB in size

The memory is organized as an array or a table. Each row is 1 byte. 1 byte is 1 bit. 1 byte = 1 word

• Step 1: Do something
• Step 2: Do something
• Step 3: Do something
• … : …

A sequential step is a single task; for example a 1 to x.

Ask a question that is answered with a logic answer. The answer can be true/false. For example:

if (x > 0) add 1 to x
else substract 1 from x

Iterative steps.

add 1/2 cup to mixture
while mixture is dry