Computer Systems a Programmer s Perspective

1. Basics

  • Main Memory: a temporary storage device that holds the data of a program. It's a collection of DRAM chips

CPUs

  • Composed or Arithmetic Logic Units and registers
  • CPUs run processes concurrently by saving and restoring context via context switching
    • This is managed by the system kernel which always resides in memory

Virtual Memory

  • Main memory is segmented such that independent processes have their own isolated memory

Kernel

  • Manages processes
  • Allocates memory
  • Performs sys calls

2. Information Storage

Hex

A - 1010 C - 1100 F - 1111

Binary

For powers of 2, i.e. x = 2n, the binary of x is just 1 followed by n zeros