system-design-refresher

Computer Architecture

Content

• Disk Storage
• RAM
• Cache
• CPU

Disk Storage

• It can be either HDD or SSD type
• This data storage is non-volatile, meaning that it maintains data without power
• Usually contains OS, applications and user files

RAM

• Primary active data holder
• Variables, intermediate computations, runtime stack and more are stored here
• Volatile memory (it requires power to retain its contents)
• > 5000 MB/s read/write speeds

Cache

• Typically measured in MBs
• Acces times are faster than RAM (just a few nanoseconds for L1 cache)
• CPU first checks L1 cache for data
  • if not found it will check L2 and L3 cache
    • if not found it will check RAM
• We store frequently used data here to improve CPU performance

CPU

• “Brain of the computer”
• Fetches, decodes and executes instructions
• Compilers translates “high” level code (C, Java, Pyhton, etc) into machine code for the CPU to execute it
• Can read from Disk, RAM and Cache