📏 Data Unit Sizes

🔹 Nibble

• Bits: 4
• Max value: 15 (0xF in hex)
• Notes: Fits exactly one hexadecimal digit.

🔹 Byte

• Bits: 8 (2 nibbles)
• Max value: 255 (0xFF)
• Notes: Standard smallest addressable unit of memory in most systems.

🔹 Word

• Bits: 16 (2 bytes)
• Max value: 65,535 (0xFFFF)
• Notes: Historically the native register size of older CPUs.

🔹 Double Word (DWORD)

• Bits: 32 (2 words)
• Max value: ~4.29 billion (0xFFFFFFFF)
• Notes: Common in 32‑bit architectures for registers, addresses, and data.

🔹 Quad Word (QWORD)

• Bits: 64 (2 double words)
• Max value: ~1.84×10¹⁹ (0xFFFFFFFFFFFFFFFF)
• Notes: Native integer and pointer size in 64‑bit architectures.

🧩 Relationships

• nibble → byte → word → dword → qword 4 → 8 → 16 → 32 → 64 (doubling each step)
• Each step = ×2 width = doubles potential representable values.