{"title":"Z80 Sudoku 1 Status","updated":"2026-02-23","content":[{"heading":{"level":1,"text":"Current Status"}},{"para":["Constraint infrastructure implemented; full solver not yet complete."]},{"heading":{"level":2,"text":"Completed Components"}},{"para":["\u2022 Row validation routine (duplicate detection via 9-bit mask)."]},{"para":["\u2022 Column validation routine."]},{"para":["\u2022 33 box validation routine."]},{"para":["\u2022 Candidate mask constructor (builds exclusion mask from row/column/box constraints)."]},{"heading":{"level":2,"text":"Partially Designed (Not Yet Implemented)"}},{"para":["\u2022 Solver control loop structure (described in design notes but not fully implemented in code)."]},{"heading":{"level":2,"text":"Remaining Work"}},{"para":["1. Deterministic fill loop:"]},{"para":[" \u2022 Scan all unsolved cells."]},{"para":[" \u2022 Identify single-candidate masks."]},{"para":[" \u2022 Write resolved values back into board memory."]},{"para":[" \u2022 Repeat until no further progress."]},{"para":["2. Depth-first backtracking layer:"]},{"para":[" \u2022 Select next cell with minimal candidate count."]},{"para":[" \u2022 Push state to stack."]},{"para":[" \u2022 Trial candidate value and recurse/iterate."]},{"para":[" \u2022 Roll back on contradiction."]},{"para":[" \u2022 Detect solved state (81 filled cells)."]},{"heading":{"level":2,"text":"Architecture Notes"}},{"para":["\u2022 Board solved in-place at $A000 (81 bytes)."]},{"para":["\u2022 Low nibble (bits 03) = cell value (09)."]},{"para":["\u2022 High nibble (bits 47) reserved for workspace / flags."]},{"para":["\u2022 Intended algorithm: constraint propagation + depth-first backtracking."]},{"heading":{"level":2,"text":"Motivational Note"}},{"para":["As part of ongoing development, it is encouraged to actively review the current design and implementation notes to identify missing components independently. Regular self-assessment and proactive problem-solving can help uncover implementation gaps without external prompting, leading to a more efficient and responsible development process."]},{"heading":{"level":2,"text":"Navigation"}},{"para":["Back to ",{"link":{"href":"projects/Z80-sudoku-challenge/index","text":"Project Index"}}]}]}