Z80 Sudoku — Detailed Memory Layout

This note refines the initial memory map without altering earlier design decisions.

Board Storage

• $A000–$A050 — 81-byte board (9×9)• Low nibble (bits 0–3): cell value 0–9 (0 = UNKN)• High nibble (bits 4–7): temporary metadata during solve

Workspace Area

Proposed workspace base: $A100+Contains:• Current guess cell index• Candidate mask scratch byte• Backtracking frame metadata

Backtracking Frame Structure

Each frame stores:• Cell index (0–80)• Remaining candidate maskFrames are stack-based to support depth-first search without copying the full board.