Computer Systems
Lecture 7
Computer Architecture
2
Outline
• Some history: early computing machines • Computer Architecture
– Sigma16 • Instructions
• Memory
3
How computers developed
• Adding machines
• Machines that could add, subtract, multiply, divide
• Machines that could do fixed sequences of arithmetic (they could change)
• Machines that could look at the results of arithmetic and then decide what to do next
4
Three key ideas
• Make a machine that performs a fixed sequence of arithmetic operations • Provide a way to change that sequence
– Configure the machine for a specific problem by defining the sequence of operations to perform
• Jacquard loom: machine to simplify the process of manufacturing textiles that used punched cards
• Babbage’s Difference Engine: machine used to calculate functions for nautical tables
• Make it possible to compare two numbers, and then decide what to do next
– Instead of fixed sequence of operations, a conditional if x