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• 1. Microprocessor and Memory Basics
• What is a microprocessor and where are they used?
• Abstract system architecture
• System communication
  • Data bus, address bus, control bus
  • Reading data from memory
  • Writing data to memory
  • The Address Capacity of Memory
• Inside the microprocessor
  • The Arithmetic and Logic Unit
  • The Program Counter
  • Registers
• Inside memory
  • Memory Read and Write Operations
  • Calculating storage space
  • Address decoders
  • Tri-state buffers
  • Multiple memory chips
  • Other types of memory
  • Memory mapped input/output

The Arithmetic and Logic Unit

The Arithmetic and Logic Unit (ALU) is responsible for performing most of the computation in a modern processor.

This includes basic arithmetic such as binary addition and subtraction, operations to shift and rotate the bits in a binary number, comparison operations (such as testing for zero, negative numbers, etc.) and logical operations such as AND, OR, XOR (exclusive OR) and NOT (negation).

What constitutes "basic" arithmetic varies according to the processor architecture. Many ARM processors include a coprocessor hardware unit which is used to perform much more complex mathematical operations such as arcsine, cosine, floating-point division, etc.

Inside the ALU is a vast array of logic gates arranged in various subcircuits (such as ripple carry adders and comparators) to perform the necessary operations. In computer design, significant effort is expended in ensuring the ALU is efficiently implemented.