Computer Architecture & Standards

Notes on computer hardware architecture, component hierarchies, and industry standards for processors and memory.

CPU Architectures

Modern computing is dominated by a few key Instruction Set Architectures (ISA):

• x86 / x86_64: Dominant in desktops, laptops, and servers (Intel, AMD).
• ARM (Advanced RISC Machines): Dominant in mobile devices and increasingly servers/desktops (Apple Silicon, AWS Graviton).
  • Architectures: ARMv7, ARMv8-A (64-bit), ARMv9.
• RISC-V: Open-standard ISA growing in embedded and specialized sectors.
• MIPS / POWER: Legacy architectures still used in networking and enterprise.

Memory Standards (RAM)

Evolution of Dual In-line Memory Modules (DIMM) and Small Outline DIMM (SO-DIMM):

• DDR3: Mainstream approx. 2007-2015.
  • Standard DIMM capacity usually up to 8GB or 16GB per module.
• DDR4: Released Q2 2014. Increased speed and lower voltage.
  • Standard module capacities up to 32GB/64GB, server modules (LRDIMM) up to 128GB+.
• DDR5: Released approx. 2020. Higher density and performance.
  • Modules starting at 16GB, theoretical capacity up to 128GB per standard DIMM.

System Hierarchy

1. CPU (ALU, Registers, Cache L1/L2/L3)
2. Main Memory (RAM)
3. Storage (SSD, HDD, NVMe)
4. I/O Interfaces (PCIe, USB, SATA, Ethernet)

Resources

• Computer Architecture (Wikipedia)
• DDR4 SDRAM (Wikipedia)