Notation

Last updated: 2026-06-19

A couple of conventions that show up everywhere in the rest of the book.

Hexadecimal

$10 and 0x10 is hexadecimal for the same number, 16 in decimal.
In this book I prefer $<number> since it's one character instead of two.

In most low-level programming, $10 is an address (decimal 16). Here it can be an address or a value — it depends on context.

0x is the C-style prefix; both just mean "read what follows as hex". In a language like C or Zig you'd write:

  int value = 0x10; // C
  const value = 0x10; // Zig

0-based vs 1-based

Mostly for beginners.

When we say "byte 0," we mean the first byte, and viceversa.

• Counting positions from 0 is 0-based;
• Counting from 1 is 1-based.

A common snag:

• There are 256 bytes between $00 and $ff.
• But $ff is 255 in decimal, not 256.
• Decimal 256 is 0x100.

Assume first means byte $0 unless stated otherwise — though some things really are 1-based. It's annoying at first, but you get used to it.