Slim build comparison

File-declared reservations

The all-resources total includes nonfixed resources even when they can be swapped out. Both totals include the unchanged 49,152-byte stack.

Where the savings come from

Representations are narrowed only where every legal value fits. The engine retains 32-bit arithmetic, 64-bit hashes, 256 history entries and the same transposition, pawn and material cache capacities. Search input safely aliases the current game; compact sorter state preserves tested move order.

The initialization arena uses 34,260 bytes of its 34,336-byte limit. Paragraph alignment and an explicit 64-byte guard leave 76 unused bytes. A native-code 80-ply test and repeated resets made no further allocations; arena-tail and stack-gap canaries passed.

Native search BUSY intervals

Three repeats per position and depth, driven through the real Ensemble 1.2 UI in DOSBox Staging 0.83. Points show medians; whiskers show the observed minimum and maximum.

Matched normal-core, 80,000-cycle emulator guests; VGA 640 x 480, 16 MiB, 1,500 handles. Read-only sampling at nominal 2 ms intervals observes BUSY transitions. Nominal sampling is not an error bound; observed sampling gaps reached 49.216 ms. Short searches are sensitive to sampling and host/emulator load. These are not physical-PC benchmarks or a universal speed guarantee.

Native system memory observations

Actual unmodified Ensemble 1.2 Perf heap fixed-byte counters. The program's displayed absolute Fixed value additionally includes a constant kernel-size contribution; these raw heap counters are not that displayed total. After searches, the global Perf Memory meter showed 837.3 KiB (previous) and 845.7 KiB (slim). It counts allocated memory including swapped blocks, not physical resident RAM. Matched configuration does not mean identical background/cache allocation state. No whole-system Memory reduction is claimed. These observations are separate from resource reservations and do not establish minimum RAM.

Tests that matched

113 host positions, 452 searches and 3,385 identical result records with 19,081,983 repeated checks; paired ASan and UBSan runs pass. Representation testing compares 9,989 values exhaustively; sorter testing compares 12,303 cases and exact move order.

The actual 16-bit geodes are also compared on eight FENs at depths 1-4, plus special moves, terminal states, repetition, self-play, saved/restored state and moved artwork. The finite suite checks native code, segmented pointers and lock thunks; it is not an exhaustive proof for every chess position.

The 32 paired searches total 114,177,759 to 107,883,512 guest dispatches (5.51% fewer), under the stated boundary model. This is controlled guest work, not measured hardware speed.

[
  {
    "case": "baseline4",
    "variant": "baseline",
    "sha256": "796ba70122e22276bbeac16ef55fa9bed87d525419072446df3afff6137d5c62",
    "ram_mib": 4,
    "searches": 8,
    "repeats_per_depth_position": 1,
    "purpose": "Finite launch/search/lifecycle smoke; not the repeated comparative timing dataset.",
    "passed": true,
    "memory": {
      "resource_fixed_bytes": 183984.0,
      "app_owned_allocated_bytes": 271808.0,
      "app_owned_resident_bytes": 271808.0,
      "code_lock_count": 0.0,
      "art_lock_count": 0.0
    },
    "lifecycle": {
      "sha256": "796ba70122e22276bbeac16ef55fa9bed87d525419072446df3afff6137d5c62",
      "closed_valid": 0,
      "reopened_ready": 1,
      "reopened_depth": 2,
      "reopened_owned_allocated_bytes": 271808,
      "reopened_code_locks": 0,
      "reopened_art_locks": 0,
      "result": "PASS"
    }
  },
  {
    "case": "slim4",
    "variant": "slim",
    "sha256": "58a4cc7c8a293913ce8069d6888cd1793aec8a05f2341a0b7276e20d27084941",
    "ram_mib": 4,
    "searches": 8,
    "repeats_per_depth_position": 1,
    "purpose": "Finite launch/search/lifecycle smoke; not the repeated comparative timing dataset.",
    "passed": true,
    "memory": {
      "resource_fixed_bytes": 128384.0,
      "app_owned_allocated_bytes": 217296.0,
      "app_owned_resident_bytes": 217296.0,
      "code_lock_count": 0.0,
      "art_lock_count": 0.0
    },
    "lifecycle": {
      "sha256": "58a4cc7c8a293913ce8069d6888cd1793aec8a05f2341a0b7276e20d27084941",
      "closed_valid": 0,
      "reopened_ready": 1,
      "reopened_depth": 2,
      "reopened_owned_allocated_bytes": 217888,
      "reopened_code_locks": 0,
      "reopened_art_locks": 0,
      "result": "PASS"
    }
  },
  {
    "case": "german4",
    "variant": "slim_german",
    "ram_mib": 4,
    "sha256": "eb65acf09895f2684a10899ba104d4166217942e0d47a5144a1cfb0bf96719c4",
    "passed": true,
    "smoke": {
      "result": "PASS",
      "sha256": "eb65acf09895f2684a10899ba104d4166217942e0d47a5144a1cfb0bf96719c4",
      "keyboard": "Illegal e2e5 rejected; Backspace+4 corrected to e2e4 and b8c6 engine reply",
      "mouse": "g1f3 accepted; g8f6 engine reply",
      "controls": [
        "No-undo message",
        "Undo restores previous human-and-engine turn",
        "New game",
        "Depth4 Computerzug produces b1c3"
      ],
      "limits": "Supplied English GeoWorks Pro1.2 runtime; German system runtime unavailable."
    },
    "lifecycle": {
      "sha256": "eb65acf09895f2684a10899ba104d4166217942e0d47a5144a1cfb0bf96719c4",
      "closed_valid": 0,
      "reopened_ready": 1,
      "reopened_depth": 2,
      "reopened_owned_allocated_bytes": 217904,
      "reopened_code_locks": 0,
      "reopened_art_locks": 0,
      "result": "PASS"
    }
  },
  {
    "case": "slim-pressure2",
    "variant": "slim",
    "ram_mib": 2,
    "sha256": "58a4cc7c8a293913ce8069d6888cd1793aec8a05f2341a0b7276e20d27084941",
    "passed": true,
    "scope": "Finite native test on this supplied English1.2 runtime with DOSBox memsize2MiB, normal core80000cycles, VGA640x480/16 and1500handles. Not a physical minimum-RAM guarantee, leak proof for all lifecycles, or proof of simultaneous completed app-load/search. Baseline2MiB five-app pressure result is historical, not rerun in this comparison. Native matched performance/footprint comparison is separate.",
    "report": "pressure2/pressure2-report.json"
  }
]

Release identity and limits

Previous English 6.3.0.4

796ba70122e22276bbeac16ef55fa9bed87d525419072446df3afff6137d5c62

Slim English 6.3.0.6

58a4cc7c8a293913ce8069d6888cd1793aec8a05f2341a0b7276e20d27084941

Slim German 6.3.0.7

eb65acf09895f2684a10899ba104d4166217942e0d47a5144a1cfb0bf96719c4

Tests use the supplied English Ensemble 1.2 installation under emulation. The German build targets that runtime too; no German system runtime was supplied. Native case statuses are retained in the accompanying report data. Physical hardware and other 1.x releases remain untested. Search is synchronous and remains bounded to requested depths 1-4; unrestricted desktop GNU Chess strength is not claimed.

The package contains source, rebuild instructions, exact-binary quick-rebuild checks, PNG/SVG exports and per-case raw CSV/JSON/JSONL evidence. This HTML works offline and loads no external resources.