Why Hexadecimal?

You now know that computers use binary. So why do assembly programmers rarely write binary directly?

The problem with binary:

Binary numbers are very long. Look at this example:

Writing long strings of 1s and 0s is slow, error-prone, and hard to read.

The solution: hexadecimal (base 16).

Hexadecimal (or "hex") uses 16 symbols:

Why hex is perfect for computers:

One hex digit represents exactly 4 bits (half a byte).

Same number, three ways:

Notice how much shorter hex is than binary.

Where you will see hex in assembly:

• Memory addresses (like 0x7FFF or 0x402000)
• ASCII codes (like 0x41 for 'A', 0x0a for newline)

• Register values in debuggers
• Color values (like 0xFF0000 for red)

Hex is written with a prefix:

In this course, we use 0x prefix: 0x0a, 0x41, 0xFF.